FreeBSD kernel kern code
sched_ule.c
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1 /*-
2  * Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice unmodified, this list of conditions, and the following
10  * disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  * notice, this list of conditions and the following disclaimer in the
13  * documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 /*
28  * This file implements the ULE scheduler. ULE supports independent CPU
29  * run queues and fine grain locking. It has superior interactive
30  * performance under load even on uni-processor systems.
31  *
32  * etymology:
33  * ULE is the last three letters in schedule. It owes its name to a
34  * generic user created for a scheduling system by Paul Mikesell at
35  * Isilon Systems and a general lack of creativity on the part of the author.
36  */
37 
38 #include <sys/cdefs.h>
39 __FBSDID("$BSDSUniX$");
40 
41 #include "opt_hwpmc_hooks.h"
42 #include "opt_kdtrace.h"
43 #include "opt_sched.h"
44 
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/kdb.h>
48 #include <sys/kernel.h>
49 #include <sys/ktr.h>
50 #include <sys/lock.h>
51 #include <sys/mutex.h>
52 #include <sys/proc.h>
53 #include <sys/resource.h>
54 #include <sys/resourcevar.h>
55 #include <sys/sched.h>
56 #include <sys/sdt.h>
57 #include <sys/smp.h>
58 #include <sys/sx.h>
59 #include <sys/sysctl.h>
60 #include <sys/sysproto.h>
61 #include <sys/turnstile.h>
62 #include <sys/umtx.h>
63 #include <sys/vmmeter.h>
64 #include <sys/cpuset.h>
65 #include <sys/sbuf.h>
66 
67 #ifdef HWPMC_HOOKS
68 #include <sys/pmckern.h>
69 #endif
70 
71 #ifdef KDTRACE_HOOKS
72 #include <sys/dtrace_bsd.h>
73 int dtrace_vtime_active;
74 dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
75 #endif
76 
77 #include <machine/cpu.h>
78 #include <machine/smp.h>
79 
80 #if defined(__powerpc__) && defined(E500)
81 #error "This architecture is not currently compatible with ULE"
82 #endif
83 
84 #define KTR_ULE 0
85 
86 #define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
87 #define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU)))
88 #define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load"))
89 
90 /*
91  * Thread scheduler specific section. All fields are protected
92  * by the thread lock.
93  */
94 struct td_sched {
95  struct runq *ts_runq; /* Run-queue we're queued on. */
96  short ts_flags; /* TSF_* flags. */
97  u_char ts_cpu; /* CPU that we have affinity for. */
98  int ts_rltick; /* Real last tick, for affinity. */
99  int ts_slice; /* Ticks of slice remaining. */
100  u_int ts_slptime; /* Number of ticks we vol. slept */
101  u_int ts_runtime; /* Number of ticks we were running */
102  int ts_ltick; /* Last tick that we were running on */
103  int ts_ftick; /* First tick that we were running on */
104  int ts_ticks; /* Tick count */
105 #ifdef KTR
106  char ts_name[TS_NAME_LEN];
107 #endif
108 };
109 /* flags kept in ts_flags */
110 #define TSF_BOUND 0x0001 /* Thread can not migrate. */
111 #define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */
112 
113 static struct td_sched td_sched0;
114 
115 #define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0)
116 #define THREAD_CAN_SCHED(td, cpu) \
117  CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
118 
119 /*
120  * Priority ranges used for interactive and non-interactive timeshare
121  * threads. The timeshare priorities are split up into four ranges.
122  * The first range handles interactive threads. The last three ranges
123  * (NHALF, x, and NHALF) handle non-interactive threads with the outer
124  * ranges supporting nice values.
125  */
126 #define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1)
127 #define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2)
128 #define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE)
129 
130 #define PRI_MIN_INTERACT PRI_MIN_TIMESHARE
131 #define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1)
132 #define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE)
133 #define PRI_MAX_BATCH PRI_MAX_TIMESHARE
134 
135 /*
136  * Cpu percentage computation macros and defines.
137  *
138  * SCHED_TICK_SECS: Number of seconds to average the cpu usage across.
139  * SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across.
140  * SCHED_TICK_MAX: Maximum number of ticks before scaling back.
141  * SCHED_TICK_SHIFT: Shift factor to avoid rounding away results.
142  * SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count.
143  * SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks.
144  */
145 #define SCHED_TICK_SECS 10
146 #define SCHED_TICK_TARG (hz * SCHED_TICK_SECS)
147 #define SCHED_TICK_MAX (SCHED_TICK_TARG + hz)
148 #define SCHED_TICK_SHIFT 10
149 #define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT)
150 #define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz))
151 
152 /*
153  * These macros determine priorities for non-interactive threads. They are
154  * assigned a priority based on their recent cpu utilization as expressed
155  * by the ratio of ticks to the tick total. NHALF priorities at the start
156  * and end of the MIN to MAX timeshare range are only reachable with negative
157  * or positive nice respectively.
158  *
159  * PRI_RANGE: Priority range for utilization dependent priorities.
160  * PRI_NRESV: Number of nice values.
161  * PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total.
162  * PRI_NICE: Determines the part of the priority inherited from nice.
163  */
164 #define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN)
165 #define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
166 #define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF)
167 #define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF)
168 #define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1)
169 #define SCHED_PRI_TICKS(ts) \
170  (SCHED_TICK_HZ((ts)) / \
171  (roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE))
172 #define SCHED_PRI_NICE(nice) (nice)
173 
174 /*
175  * These determine the interactivity of a process. Interactivity differs from
176  * cpu utilization in that it expresses the voluntary time slept vs time ran
177  * while cpu utilization includes all time not running. This more accurately
178  * models the intent of the thread.
179  *
180  * SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate
181  * before throttling back.
182  * SLP_RUN_FORK: Maximum slp+run time to inherit at fork time.
183  * INTERACT_MAX: Maximum interactivity value. Smaller is better.
184  * INTERACT_THRESH: Threshold for placement on the current runq.
185  */
186 #define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT)
187 #define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT)
188 #define SCHED_INTERACT_MAX (100)
189 #define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
190 #define SCHED_INTERACT_THRESH (30)
191 
192 /* Flags kept in td_flags. */
193 #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
194 
195 /*
196  * tickincr: Converts a stathz tick into a hz domain scaled by
197  * the shift factor. Without the shift the error rate
198  * due to rounding would be unacceptably high.
199  * realstathz: stathz is sometimes 0 and run off of hz.
200  * sched_slice: Runtime of each thread before rescheduling.
201  * preempt_thresh: Priority threshold for preemption and remote IPIs.
202  */
203 static int sched_interact = SCHED_INTERACT_THRESH;
204 static int realstathz = 127;
205 static int tickincr = 8 << SCHED_TICK_SHIFT;
206 static int sched_slice = 12;
207 #ifdef PREEMPTION
208 #ifdef FULL_PREEMPTION
209 static int preempt_thresh = PRI_MAX_IDLE;
210 #else
211 static int preempt_thresh = PRI_MIN_KERN;
212 #endif
213 #else
214 static int preempt_thresh = 0;
215 #endif
216 static int static_boost = PRI_MIN_BATCH;
217 static int sched_idlespins = 10000;
218 static int sched_idlespinthresh = -1;
219 
220 /*
221  * tdq - per processor runqs and statistics. All fields are protected by the
222  * tdq_lock. The load and lowpri may be accessed without to avoid excess
223  * locking in sched_pickcpu();
224  */
225 struct tdq {
226  /* Ordered to improve efficiency of cpu_search() and switch(). */
227  struct mtx tdq_lock; /* run queue lock. */
228  struct cpu_group *tdq_cg; /* Pointer to cpu topology. */
229  volatile int tdq_load; /* Aggregate load. */
230  volatile int tdq_cpu_idle; /* cpu_idle() is active. */
231  int tdq_sysload; /* For loadavg, !ITHD load. */
232  int tdq_transferable; /* Transferable thread count. */
233  short tdq_switchcnt; /* Switches this tick. */
234  short tdq_oldswitchcnt; /* Switches last tick. */
235  u_char tdq_lowpri; /* Lowest priority thread. */
236  u_char tdq_ipipending; /* IPI pending. */
237  u_char tdq_idx; /* Current insert index. */
238  u_char tdq_ridx; /* Current removal index. */
239  struct runq tdq_realtime; /* real-time run queue. */
240  struct runq tdq_timeshare; /* timeshare run queue. */
241  struct runq tdq_idle; /* Queue of IDLE threads. */
242  char tdq_name[TDQ_NAME_LEN];
243 #ifdef KTR
244  char tdq_loadname[TDQ_LOADNAME_LEN];
245 #endif
246 } __aligned(64);
247 
248 /* Idle thread states and config. */
249 #define TDQ_RUNNING 1
250 #define TDQ_IDLE 2
251 
252 #ifdef SMP
253 struct cpu_group *cpu_top; /* CPU topology */
254 
255 #define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000))
256 #define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity))
257 
258 /*
259  * Run-time tunables.
260  */
261 static int rebalance = 1;
262 static int balance_interval = 128; /* Default set in sched_initticks(). */
263 static int affinity;
264 static int steal_idle = 1;
265 static int steal_thresh = 2;
266 
267 /*
268  * One thread queue per processor.
269  */
270 static struct tdq tdq_cpu[MAXCPU];
271 static struct tdq *balance_tdq;
272 static int balance_ticks;
273 static DPCPU_DEFINE(uint32_t, randomval);
274 
275 #define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)])
276 #define TDQ_CPU(x) (&tdq_cpu[(x)])
277 #define TDQ_ID(x) ((int)((x) - tdq_cpu))
278 #else /* !SMP */
279 static struct tdq tdq_cpu;
280 
281 #define TDQ_ID(x) (0)
282 #define TDQ_SELF() (&tdq_cpu)
283 #define TDQ_CPU(x) (&tdq_cpu)
284 #endif
285 
286 #define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type))
287 #define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t)))
288 #define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f))
289 #define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t)))
290 #define TDQ_LOCKPTR(t) (&(t)->tdq_lock)
291 
292 static void sched_priority(struct thread *);
293 static void sched_thread_priority(struct thread *, u_char);
294 static int sched_interact_score(struct thread *);
295 static void sched_interact_update(struct thread *);
296 static void sched_interact_fork(struct thread *);
297 static void sched_pctcpu_update(struct td_sched *, int);
298 
299 /* Operations on per processor queues */
300 static struct thread *tdq_choose(struct tdq *);
301 static void tdq_setup(struct tdq *);
302 static void tdq_load_add(struct tdq *, struct thread *);
303 static void tdq_load_rem(struct tdq *, struct thread *);
304 static __inline void tdq_runq_add(struct tdq *, struct thread *, int);
305 static __inline void tdq_runq_rem(struct tdq *, struct thread *);
306 static inline int sched_shouldpreempt(int, int, int);
307 void tdq_print(int cpu);
308 static void runq_print(struct runq *rq);
309 static void tdq_add(struct tdq *, struct thread *, int);
310 #ifdef SMP
311 static int tdq_move(struct tdq *, struct tdq *);
312 static int tdq_idled(struct tdq *);
313 static void tdq_notify(struct tdq *, struct thread *);
314 static struct thread *tdq_steal(struct tdq *, int);
315 static struct thread *runq_steal(struct runq *, int);
316 static int sched_pickcpu(struct thread *, int);
317 static void sched_balance(void);
318 static int sched_balance_pair(struct tdq *, struct tdq *);
319 static inline struct tdq *sched_setcpu(struct thread *, int, int);
320 static inline void thread_unblock_switch(struct thread *, struct mtx *);
321 static struct mtx *sched_switch_migrate(struct tdq *, struct thread *, int);
322 static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS);
323 static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb,
324  struct cpu_group *cg, int indent);
325 #endif
326 
327 static void sched_setup(void *dummy);
328 SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
329 
330 static void sched_initticks(void *dummy);
331 SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
332  NULL);
333 
334 SDT_PROVIDER_DEFINE(sched);
335 
336 SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
337  "struct proc *", "uint8_t");
338 SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
339  "struct proc *", "void *");
340 SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
341  "struct proc *", "void *", "int");
342 SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
343  "struct proc *", "uint8_t", "struct thread *");
344 SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
345 SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
346  "struct proc *");
347 SDT_PROBE_DEFINE(sched, , , on__cpu);
348 SDT_PROBE_DEFINE(sched, , , remain__cpu);
349 SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
350  "struct proc *");
351 
352 /*
353  * Print the threads waiting on a run-queue.
354  */
355 static void
356 runq_print(struct runq *rq)
357 {
358  struct rqhead *rqh;
359  struct thread *td;
360  int pri;
361  int j;
362  int i;
363 
364  for (i = 0; i < RQB_LEN; i++) {
365  printf("\t\trunq bits %d 0x%zx\n",
366  i, rq->rq_status.rqb_bits[i]);
367  for (j = 0; j < RQB_BPW; j++)
368  if (rq->rq_status.rqb_bits[i] & (1ul << j)) {
369  pri = j + (i << RQB_L2BPW);
370  rqh = &rq->rq_queues[pri];
371  TAILQ_FOREACH(td, rqh, td_runq) {
372  printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n",
373  td, td->td_name, td->td_priority,
374  td->td_rqindex, pri);
375  }
376  }
377  }
378 }
379 
380 /*
381  * Print the status of a per-cpu thread queue. Should be a ddb show cmd.
382  */
383 void
384 tdq_print(int cpu)
385 {
386  struct tdq *tdq;
387 
388  tdq = TDQ_CPU(cpu);
389 
390  printf("tdq %d:\n", TDQ_ID(tdq));
391  printf("\tlock %p\n", TDQ_LOCKPTR(tdq));
392  printf("\tLock name: %s\n", tdq->tdq_name);
393  printf("\tload: %d\n", tdq->tdq_load);
394  printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt);
395  printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt);
396  printf("\ttimeshare idx: %d\n", tdq->tdq_idx);
397  printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx);
398  printf("\tload transferable: %d\n", tdq->tdq_transferable);
399  printf("\tlowest priority: %d\n", tdq->tdq_lowpri);
400  printf("\trealtime runq:\n");
401  runq_print(&tdq->tdq_realtime);
402  printf("\ttimeshare runq:\n");
403  runq_print(&tdq->tdq_timeshare);
404  printf("\tidle runq:\n");
405  runq_print(&tdq->tdq_idle);
406 }
407 
408 static inline int
409 sched_shouldpreempt(int pri, int cpri, int remote)
410 {
411  /*
412  * If the new priority is not better than the current priority there is
413  * nothing to do.
414  */
415  if (pri >= cpri)
416  return (0);
417  /*
418  * Always preempt idle.
419  */
420  if (cpri >= PRI_MIN_IDLE)
421  return (1);
422  /*
423  * If preemption is disabled don't preempt others.
424  */
425  if (preempt_thresh == 0)
426  return (0);
427  /*
428  * Preempt if we exceed the threshold.
429  */
430  if (pri <= preempt_thresh)
431  return (1);
432  /*
433  * If we're interactive or better and there is non-interactive
434  * or worse running preempt only remote processors.
435  */
436  if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT)
437  return (1);
438  return (0);
439 }
440 
441 /*
442  * Add a thread to the actual run-queue. Keeps transferable counts up to
443  * date with what is actually on the run-queue. Selects the correct
444  * queue position for timeshare threads.
445  */
446 static __inline void
447 tdq_runq_add(struct tdq *tdq, struct thread *td, int flags)
448 {
449  struct td_sched *ts;
450  u_char pri;
451 
452  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
453  THREAD_LOCK_ASSERT(td, MA_OWNED);
454 
455  pri = td->td_priority;
456  ts = td->td_sched;
457  TD_SET_RUNQ(td);
458  if (THREAD_CAN_MIGRATE(td)) {
459  tdq->tdq_transferable++;
460  ts->ts_flags |= TSF_XFERABLE;
461  }
462  if (pri < PRI_MIN_BATCH) {
463  ts->ts_runq = &tdq->tdq_realtime;
464  } else if (pri <= PRI_MAX_BATCH) {
465  ts->ts_runq = &tdq->tdq_timeshare;
466  KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH,
467  ("Invalid priority %d on timeshare runq", pri));
468  /*
469  * This queue contains only priorities between MIN and MAX
470  * realtime. Use the whole queue to represent these values.
471  */
472  if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) {
473  pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE;
474  pri = (pri + tdq->tdq_idx) % RQ_NQS;
475  /*
476  * This effectively shortens the queue by one so we
477  * can have a one slot difference between idx and
478  * ridx while we wait for threads to drain.
479  */
480  if (tdq->tdq_ridx != tdq->tdq_idx &&
481  pri == tdq->tdq_ridx)
482  pri = (unsigned char)(pri - 1) % RQ_NQS;
483  } else
484  pri = tdq->tdq_ridx;
485  runq_add_pri(ts->ts_runq, td, pri, flags);
486  return;
487  } else
488  ts->ts_runq = &tdq->tdq_idle;
489  runq_add(ts->ts_runq, td, flags);
490 }
491 
492 /*
493  * Remove a thread from a run-queue. This typically happens when a thread
494  * is selected to run. Running threads are not on the queue and the
495  * transferable count does not reflect them.
496  */
497 static __inline void
498 tdq_runq_rem(struct tdq *tdq, struct thread *td)
499 {
500  struct td_sched *ts;
501 
502  ts = td->td_sched;
503  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
504  KASSERT(ts->ts_runq != NULL,
505  ("tdq_runq_remove: thread %p null ts_runq", td));
506  if (ts->ts_flags & TSF_XFERABLE) {
507  tdq->tdq_transferable--;
508  ts->ts_flags &= ~TSF_XFERABLE;
509  }
510  if (ts->ts_runq == &tdq->tdq_timeshare) {
511  if (tdq->tdq_idx != tdq->tdq_ridx)
512  runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx);
513  else
514  runq_remove_idx(ts->ts_runq, td, NULL);
515  } else
516  runq_remove(ts->ts_runq, td);
517 }
518 
519 /*
520  * Load is maintained for all threads RUNNING and ON_RUNQ. Add the load
521  * for this thread to the referenced thread queue.
522  */
523 static void
524 tdq_load_add(struct tdq *tdq, struct thread *td)
525 {
526 
527  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
528  THREAD_LOCK_ASSERT(td, MA_OWNED);
529 
530  tdq->tdq_load++;
531  if ((td->td_flags & TDF_NOLOAD) == 0)
532  tdq->tdq_sysload++;
533  KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
534  SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
535 }
536 
537 /*
538  * Remove the load from a thread that is transitioning to a sleep state or
539  * exiting.
540  */
541 static void
542 tdq_load_rem(struct tdq *tdq, struct thread *td)
543 {
544 
545  THREAD_LOCK_ASSERT(td, MA_OWNED);
546  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
547  KASSERT(tdq->tdq_load != 0,
548  ("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq)));
549 
550  tdq->tdq_load--;
551  if ((td->td_flags & TDF_NOLOAD) == 0)
552  tdq->tdq_sysload--;
553  KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
554  SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
555 }
556 
557 /*
558  * Set lowpri to its exact value by searching the run-queue and
559  * evaluating curthread. curthread may be passed as an optimization.
560  */
561 static void
562 tdq_setlowpri(struct tdq *tdq, struct thread *ctd)
563 {
564  struct thread *td;
565 
566  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
567  if (ctd == NULL)
568  ctd = pcpu_find(TDQ_ID(tdq))->pc_curthread;
569  td = tdq_choose(tdq);
570  if (td == NULL || td->td_priority > ctd->td_priority)
571  tdq->tdq_lowpri = ctd->td_priority;
572  else
573  tdq->tdq_lowpri = td->td_priority;
574 }
575 
576 #ifdef SMP
577 struct cpu_search {
578  cpuset_t cs_mask;
579  u_int cs_prefer;
580  int cs_pri; /* Min priority for low. */
581  int cs_limit; /* Max load for low, min load for high. */
582  int cs_cpu;
583  int cs_load;
584 };
585 
586 #define CPU_SEARCH_LOWEST 0x1
587 #define CPU_SEARCH_HIGHEST 0x2
588 #define CPU_SEARCH_BOTH (CPU_SEARCH_LOWEST|CPU_SEARCH_HIGHEST)
589 
590 #define CPUSET_FOREACH(cpu, mask) \
591  for ((cpu) = 0; (cpu) <= mp_maxid; (cpu)++) \
592  if (CPU_ISSET(cpu, &mask))
593 
594 static __inline int cpu_search(const struct cpu_group *cg, struct cpu_search *low,
595  struct cpu_search *high, const int match);
596 int cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low);
597 int cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high);
598 int cpu_search_both(const struct cpu_group *cg, struct cpu_search *low,
599  struct cpu_search *high);
600 
601 /*
602  * Search the tree of cpu_groups for the lowest or highest loaded cpu
603  * according to the match argument. This routine actually compares the
604  * load on all paths through the tree and finds the least loaded cpu on
605  * the least loaded path, which may differ from the least loaded cpu in
606  * the system. This balances work among caches and busses.
607  *
608  * This inline is instantiated in three forms below using constants for the
609  * match argument. It is reduced to the minimum set for each case. It is
610  * also recursive to the depth of the tree.
611  */
612 static __inline int
613 cpu_search(const struct cpu_group *cg, struct cpu_search *low,
614  struct cpu_search *high, const int match)
615 {
616  struct cpu_search lgroup;
617  struct cpu_search hgroup;
618  cpuset_t cpumask;
619  struct cpu_group *child;
620  struct tdq *tdq;
621  int cpu, i, hload, lload, load, total, rnd, *rndptr;
622 
623  total = 0;
624  cpumask = cg->cg_mask;
625  if (match & CPU_SEARCH_LOWEST) {
626  lload = INT_MAX;
627  lgroup = *low;
628  }
629  if (match & CPU_SEARCH_HIGHEST) {
630  hload = INT_MIN;
631  hgroup = *high;
632  }
633 
634  /* Iterate through the child CPU groups and then remaining CPUs. */
635  for (i = cg->cg_children, cpu = mp_maxid; ; ) {
636  if (i == 0) {
637 #ifdef HAVE_INLINE_FFSL
638  cpu = CPU_FFS(&cpumask) - 1;
639 #else
640  while (cpu >= 0 && !CPU_ISSET(cpu, &cpumask))
641  cpu--;
642 #endif
643  if (cpu < 0)
644  break;
645  child = NULL;
646  } else
647  child = &cg->cg_child[i - 1];
648 
649  if (match & CPU_SEARCH_LOWEST)
650  lgroup.cs_cpu = -1;
651  if (match & CPU_SEARCH_HIGHEST)
652  hgroup.cs_cpu = -1;
653  if (child) { /* Handle child CPU group. */
654  CPU_NAND(&cpumask, &child->cg_mask);
655  switch (match) {
656  case CPU_SEARCH_LOWEST:
657  load = cpu_search_lowest(child, &lgroup);
658  break;
659  case CPU_SEARCH_HIGHEST:
660  load = cpu_search_highest(child, &hgroup);
661  break;
662  case CPU_SEARCH_BOTH:
663  load = cpu_search_both(child, &lgroup, &hgroup);
664  break;
665  }
666  } else { /* Handle child CPU. */
667  CPU_CLR(cpu, &cpumask);
668  tdq = TDQ_CPU(cpu);
669  load = tdq->tdq_load * 256;
670  rndptr = DPCPU_PTR(randomval);
671  rnd = (*rndptr = *rndptr * 69069 + 5) >> 26;
672  if (match & CPU_SEARCH_LOWEST) {
673  if (cpu == low->cs_prefer)
674  load -= 64;
675  /* If that CPU is allowed and get data. */
676  if (tdq->tdq_lowpri > lgroup.cs_pri &&
677  tdq->tdq_load <= lgroup.cs_limit &&
678  CPU_ISSET(cpu, &lgroup.cs_mask)) {
679  lgroup.cs_cpu = cpu;
680  lgroup.cs_load = load - rnd;
681  }
682  }
683  if (match & CPU_SEARCH_HIGHEST)
684  if (tdq->tdq_load >= hgroup.cs_limit &&
685  tdq->tdq_transferable &&
686  CPU_ISSET(cpu, &hgroup.cs_mask)) {
687  hgroup.cs_cpu = cpu;
688  hgroup.cs_load = load - rnd;
689  }
690  }
691  total += load;
692 
693  /* We have info about child item. Compare it. */
694  if (match & CPU_SEARCH_LOWEST) {
695  if (lgroup.cs_cpu >= 0 &&
696  (load < lload ||
697  (load == lload && lgroup.cs_load < low->cs_load))) {
698  lload = load;
699  low->cs_cpu = lgroup.cs_cpu;
700  low->cs_load = lgroup.cs_load;
701  }
702  }
703  if (match & CPU_SEARCH_HIGHEST)
704  if (hgroup.cs_cpu >= 0 &&
705  (load > hload ||
706  (load == hload && hgroup.cs_load > high->cs_load))) {
707  hload = load;
708  high->cs_cpu = hgroup.cs_cpu;
709  high->cs_load = hgroup.cs_load;
710  }
711  if (child) {
712  i--;
713  if (i == 0 && CPU_EMPTY(&cpumask))
714  break;
715  }
716 #ifndef HAVE_INLINE_FFSL
717  else
718  cpu--;
719 #endif
720  }
721  return (total);
722 }
723 
724 /*
725  * cpu_search instantiations must pass constants to maintain the inline
726  * optimization.
727  */
728 int
729 cpu_search_lowest(const struct cpu_group *cg, struct cpu_search *low)
730 {
731  return cpu_search(cg, low, NULL, CPU_SEARCH_LOWEST);
732 }
733 
734 int
735 cpu_search_highest(const struct cpu_group *cg, struct cpu_search *high)
736 {
737  return cpu_search(cg, NULL, high, CPU_SEARCH_HIGHEST);
738 }
739 
740 int
741 cpu_search_both(const struct cpu_group *cg, struct cpu_search *low,
742  struct cpu_search *high)
743 {
744  return cpu_search(cg, low, high, CPU_SEARCH_BOTH);
745 }
746 
747 /*
748  * Find the cpu with the least load via the least loaded path that has a
749  * lowpri greater than pri pri. A pri of -1 indicates any priority is
750  * acceptable.
751  */
752 static inline int
753 sched_lowest(const struct cpu_group *cg, cpuset_t mask, int pri, int maxload,
754  int prefer)
755 {
756  struct cpu_search low;
757 
758  low.cs_cpu = -1;
759  low.cs_prefer = prefer;
760  low.cs_mask = mask;
761  low.cs_pri = pri;
762  low.cs_limit = maxload;
763  cpu_search_lowest(cg, &low);
764  return low.cs_cpu;
765 }
766 
767 /*
768  * Find the cpu with the highest load via the highest loaded path.
769  */
770 static inline int
771 sched_highest(const struct cpu_group *cg, cpuset_t mask, int minload)
772 {
773  struct cpu_search high;
774 
775  high.cs_cpu = -1;
776  high.cs_mask = mask;
777  high.cs_limit = minload;
778  cpu_search_highest(cg, &high);
779  return high.cs_cpu;
780 }
781 
782 static void
783 sched_balance_group(struct cpu_group *cg)
784 {
785  cpuset_t hmask, lmask;
786  int high, low, anylow;
787 
788  CPU_FILL(&hmask);
789  for (;;) {
790  high = sched_highest(cg, hmask, 1);
791  /* Stop if there is no more CPU with transferrable threads. */
792  if (high == -1)
793  break;
794  CPU_CLR(high, &hmask);
795  CPU_COPY(&hmask, &lmask);
796  /* Stop if there is no more CPU left for low. */
797  if (CPU_EMPTY(&lmask))
798  break;
799  anylow = 1;
800 nextlow:
801  low = sched_lowest(cg, lmask, -1,
802  TDQ_CPU(high)->tdq_load - 1, high);
803  /* Stop if we looked well and found no less loaded CPU. */
804  if (anylow && low == -1)
805  break;
806  /* Go to next high if we found no less loaded CPU. */
807  if (low == -1)
808  continue;
809  /* Transfer thread from high to low. */
810  if (sched_balance_pair(TDQ_CPU(high), TDQ_CPU(low))) {
811  /* CPU that got thread can no longer be a donor. */
812  CPU_CLR(low, &hmask);
813  } else {
814  /*
815  * If failed, then there is no threads on high
816  * that can run on this low. Drop low from low
817  * mask and look for different one.
818  */
819  CPU_CLR(low, &lmask);
820  anylow = 0;
821  goto nextlow;
822  }
823  }
824 }
825 
826 static void
827 sched_balance(void)
828 {
829  struct tdq *tdq;
830 
831  /*
832  * Select a random time between .5 * balance_interval and
833  * 1.5 * balance_interval.
834  */
835  balance_ticks = max(balance_interval / 2, 1);
836  balance_ticks += random() % balance_interval;
837  if (smp_started == 0 || rebalance == 0)
838  return;
839  tdq = TDQ_SELF();
840  TDQ_UNLOCK(tdq);
841  sched_balance_group(cpu_top);
842  TDQ_LOCK(tdq);
843 }
844 
845 /*
846  * Lock two thread queues using their address to maintain lock order.
847  */
848 static void
849 tdq_lock_pair(struct tdq *one, struct tdq *two)
850 {
851  if (one < two) {
852  TDQ_LOCK(one);
853  TDQ_LOCK_FLAGS(two, MTX_DUPOK);
854  } else {
855  TDQ_LOCK(two);
856  TDQ_LOCK_FLAGS(one, MTX_DUPOK);
857  }
858 }
859 
860 /*
861  * Unlock two thread queues. Order is not important here.
862  */
863 static void
864 tdq_unlock_pair(struct tdq *one, struct tdq *two)
865 {
866  TDQ_UNLOCK(one);
867  TDQ_UNLOCK(two);
868 }
869 
870 /*
871  * Transfer load between two imbalanced thread queues.
872  */
873 static int
874 sched_balance_pair(struct tdq *high, struct tdq *low)
875 {
876  int moved;
877  int cpu;
878 
879  tdq_lock_pair(high, low);
880  moved = 0;
881  /*
882  * Determine what the imbalance is and then adjust that to how many
883  * threads we actually have to give up (transferable).
884  */
885  if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load &&
886  (moved = tdq_move(high, low)) > 0) {
887  /*
888  * In case the target isn't the current cpu IPI it to force a
889  * reschedule with the new workload.
890  */
891  cpu = TDQ_ID(low);
892  sched_pin();
893  if (cpu != PCPU_GET(cpuid))
894  ipi_cpu(cpu, IPI_PREEMPT);
895  sched_unpin();
896  }
897  tdq_unlock_pair(high, low);
898  return (moved);
899 }
900 
901 /*
902  * Move a thread from one thread queue to another.
903  */
904 static int
905 tdq_move(struct tdq *from, struct tdq *to)
906 {
907  struct td_sched *ts;
908  struct thread *td;
909  struct tdq *tdq;
910  int cpu;
911 
912  TDQ_LOCK_ASSERT(from, MA_OWNED);
913  TDQ_LOCK_ASSERT(to, MA_OWNED);
914 
915  tdq = from;
916  cpu = TDQ_ID(to);
917  td = tdq_steal(tdq, cpu);
918  if (td == NULL)
919  return (0);
920  ts = td->td_sched;
921  /*
922  * Although the run queue is locked the thread may be blocked. Lock
923  * it to clear this and acquire the run-queue lock.
924  */
925  thread_lock(td);
926  /* Drop recursive lock on from acquired via thread_lock(). */
927  TDQ_UNLOCK(from);
928  sched_rem(td);
929  ts->ts_cpu = cpu;
930  td->td_lock = TDQ_LOCKPTR(to);
931  tdq_add(to, td, SRQ_YIELDING);
932  return (1);
933 }
934 
935 /*
936  * This tdq has idled. Try to steal a thread from another cpu and switch
937  * to it.
938  */
939 static int
940 tdq_idled(struct tdq *tdq)
941 {
942  struct cpu_group *cg;
943  struct tdq *steal;
944  cpuset_t mask;
945  int thresh;
946  int cpu;
947 
948  if (smp_started == 0 || steal_idle == 0)
949  return (1);
950  CPU_FILL(&mask);
951  CPU_CLR(PCPU_GET(cpuid), &mask);
952  /* We don't want to be preempted while we're iterating. */
953  spinlock_enter();
954  for (cg = tdq->tdq_cg; cg != NULL; ) {
955  if ((cg->cg_flags & CG_FLAG_THREAD) == 0)
956  thresh = steal_thresh;
957  else
958  thresh = 1;
959  cpu = sched_highest(cg, mask, thresh);
960  if (cpu == -1) {
961  cg = cg->cg_parent;
962  continue;
963  }
964  steal = TDQ_CPU(cpu);
965  CPU_CLR(cpu, &mask);
966  tdq_lock_pair(tdq, steal);
967  if (steal->tdq_load < thresh || steal->tdq_transferable == 0) {
968  tdq_unlock_pair(tdq, steal);
969  continue;
970  }
971  /*
972  * If a thread was added while interrupts were disabled don't
973  * steal one here. If we fail to acquire one due to affinity
974  * restrictions loop again with this cpu removed from the
975  * set.
976  */
977  if (tdq->tdq_load == 0 && tdq_move(steal, tdq) == 0) {
978  tdq_unlock_pair(tdq, steal);
979  continue;
980  }
981  spinlock_exit();
982  TDQ_UNLOCK(steal);
983  mi_switch(SW_VOL | SWT_IDLE, NULL);
984  thread_unlock(curthread);
985 
986  return (0);
987  }
988  spinlock_exit();
989  return (1);
990 }
991 
992 /*
993  * Notify a remote cpu of new work. Sends an IPI if criteria are met.
994  */
995 static void
996 tdq_notify(struct tdq *tdq, struct thread *td)
997 {
998  struct thread *ctd;
999  int pri;
1000  int cpu;
1001 
1002  if (tdq->tdq_ipipending)
1003  return;
1004  cpu = td->td_sched->ts_cpu;
1005  pri = td->td_priority;
1006  ctd = pcpu_find(cpu)->pc_curthread;
1007  if (!sched_shouldpreempt(pri, ctd->td_priority, 1))
1008  return;
1009 
1010  /*
1011  * Make sure that tdq_load updated before calling this function
1012  * is globally visible before we read tdq_cpu_idle. Idle thread
1013  * accesses both of them without locks, and the order is important.
1014  */
1015  mb();
1016 
1017  if (TD_IS_IDLETHREAD(ctd)) {
1018  /*
1019  * If the MD code has an idle wakeup routine try that before
1020  * falling back to IPI.
1021  */
1022  if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu))
1023  return;
1024  }
1025  tdq->tdq_ipipending = 1;
1026  ipi_cpu(cpu, IPI_PREEMPT);
1027 }
1028 
1029 /*
1030  * Steals load from a timeshare queue. Honors the rotating queue head
1031  * index.
1032  */
1033 static struct thread *
1034 runq_steal_from(struct runq *rq, int cpu, u_char start)
1035 {
1036  struct rqbits *rqb;
1037  struct rqhead *rqh;
1038  struct thread *td, *first;
1039  int bit;
1040  int pri;
1041  int i;
1042 
1043  rqb = &rq->rq_status;
1044  bit = start & (RQB_BPW -1);
1045  pri = 0;
1046  first = NULL;
1047 again:
1048  for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) {
1049  if (rqb->rqb_bits[i] == 0)
1050  continue;
1051  if (bit != 0) {
1052  for (pri = bit; pri < RQB_BPW; pri++)
1053  if (rqb->rqb_bits[i] & (1ul << pri))
1054  break;
1055  if (pri >= RQB_BPW)
1056  continue;
1057  } else
1058  pri = RQB_FFS(rqb->rqb_bits[i]);
1059  pri += (i << RQB_L2BPW);
1060  rqh = &rq->rq_queues[pri];
1061  TAILQ_FOREACH(td, rqh, td_runq) {
1062  if (first && THREAD_CAN_MIGRATE(td) &&
1063  THREAD_CAN_SCHED(td, cpu))
1064  return (td);
1065  first = td;
1066  }
1067  }
1068  if (start != 0) {
1069  start = 0;
1070  goto again;
1071  }
1072 
1073  if (first && THREAD_CAN_MIGRATE(first) &&
1074  THREAD_CAN_SCHED(first, cpu))
1075  return (first);
1076  return (NULL);
1077 }
1078 
1079 /*
1080  * Steals load from a standard linear queue.
1081  */
1082 static struct thread *
1083 runq_steal(struct runq *rq, int cpu)
1084 {
1085  struct rqhead *rqh;
1086  struct rqbits *rqb;
1087  struct thread *td;
1088  int word;
1089  int bit;
1090 
1091  rqb = &rq->rq_status;
1092  for (word = 0; word < RQB_LEN; word++) {
1093  if (rqb->rqb_bits[word] == 0)
1094  continue;
1095  for (bit = 0; bit < RQB_BPW; bit++) {
1096  if ((rqb->rqb_bits[word] & (1ul << bit)) == 0)
1097  continue;
1098  rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
1099  TAILQ_FOREACH(td, rqh, td_runq)
1100  if (THREAD_CAN_MIGRATE(td) &&
1101  THREAD_CAN_SCHED(td, cpu))
1102  return (td);
1103  }
1104  }
1105  return (NULL);
1106 }
1107 
1108 /*
1109  * Attempt to steal a thread in priority order from a thread queue.
1110  */
1111 static struct thread *
1112 tdq_steal(struct tdq *tdq, int cpu)
1113 {
1114  struct thread *td;
1115 
1116  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1117  if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL)
1118  return (td);
1119  if ((td = runq_steal_from(&tdq->tdq_timeshare,
1120  cpu, tdq->tdq_ridx)) != NULL)
1121  return (td);
1122  return (runq_steal(&tdq->tdq_idle, cpu));
1123 }
1124 
1125 /*
1126  * Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the
1127  * current lock and returns with the assigned queue locked.
1128  */
1129 static inline struct tdq *
1130 sched_setcpu(struct thread *td, int cpu, int flags)
1131 {
1132 
1133  struct tdq *tdq;
1134 
1135  THREAD_LOCK_ASSERT(td, MA_OWNED);
1136  tdq = TDQ_CPU(cpu);
1137  td->td_sched->ts_cpu = cpu;
1138  /*
1139  * If the lock matches just return the queue.
1140  */
1141  if (td->td_lock == TDQ_LOCKPTR(tdq))
1142  return (tdq);
1143 #ifdef notyet
1144  /*
1145  * If the thread isn't running its lockptr is a
1146  * turnstile or a sleepqueue. We can just lock_set without
1147  * blocking.
1148  */
1149  if (TD_CAN_RUN(td)) {
1150  TDQ_LOCK(tdq);
1151  thread_lock_set(td, TDQ_LOCKPTR(tdq));
1152  return (tdq);
1153  }
1154 #endif
1155  /*
1156  * The hard case, migration, we need to block the thread first to
1157  * prevent order reversals with other cpus locks.
1158  */
1159  spinlock_enter();
1160  thread_lock_block(td);
1161  TDQ_LOCK(tdq);
1162  thread_lock_unblock(td, TDQ_LOCKPTR(tdq));
1163  spinlock_exit();
1164  return (tdq);
1165 }
1166 
1167 SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding");
1168 SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity");
1169 SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity");
1170 SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load");
1171 SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu");
1172 SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration");
1173 
1174 static int
1175 sched_pickcpu(struct thread *td, int flags)
1176 {
1177  struct cpu_group *cg, *ccg;
1178  struct td_sched *ts;
1179  struct tdq *tdq;
1180  cpuset_t mask;
1181  int cpu, pri, self;
1182 
1183  self = PCPU_GET(cpuid);
1184  ts = td->td_sched;
1185  if (smp_started == 0)
1186  return (self);
1187  /*
1188  * Don't migrate a running thread from sched_switch().
1189  */
1190  if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td))
1191  return (ts->ts_cpu);
1192  /*
1193  * Prefer to run interrupt threads on the processors that generate
1194  * the interrupt.
1195  */
1196  pri = td->td_priority;
1197  if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) &&
1198  curthread->td_intr_nesting_level && ts->ts_cpu != self) {
1199  SCHED_STAT_INC(pickcpu_intrbind);
1200  ts->ts_cpu = self;
1201  if (TDQ_CPU(self)->tdq_lowpri > pri) {
1202  SCHED_STAT_INC(pickcpu_affinity);
1203  return (ts->ts_cpu);
1204  }
1205  }
1206  /*
1207  * If the thread can run on the last cpu and the affinity has not
1208  * expired or it is idle run it there.
1209  */
1210  tdq = TDQ_CPU(ts->ts_cpu);
1211  cg = tdq->tdq_cg;
1212  if (THREAD_CAN_SCHED(td, ts->ts_cpu) &&
1213  tdq->tdq_lowpri >= PRI_MIN_IDLE &&
1214  SCHED_AFFINITY(ts, CG_SHARE_L2)) {
1215  if (cg->cg_flags & CG_FLAG_THREAD) {
1216  CPUSET_FOREACH(cpu, cg->cg_mask) {
1217  if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE)
1218  break;
1219  }
1220  } else
1221  cpu = INT_MAX;
1222  if (cpu > mp_maxid) {
1223  SCHED_STAT_INC(pickcpu_idle_affinity);
1224  return (ts->ts_cpu);
1225  }
1226  }
1227  /*
1228  * Search for the last level cache CPU group in the tree.
1229  * Skip caches with expired affinity time and SMT groups.
1230  * Affinity to higher level caches will be handled less aggressively.
1231  */
1232  for (ccg = NULL; cg != NULL; cg = cg->cg_parent) {
1233  if (cg->cg_flags & CG_FLAG_THREAD)
1234  continue;
1235  if (!SCHED_AFFINITY(ts, cg->cg_level))
1236  continue;
1237  ccg = cg;
1238  }
1239  if (ccg != NULL)
1240  cg = ccg;
1241  cpu = -1;
1242  /* Search the group for the less loaded idle CPU we can run now. */
1243  mask = td->td_cpuset->cs_mask;
1244  if (cg != NULL && cg != cpu_top &&
1245  CPU_CMP(&cg->cg_mask, &cpu_top->cg_mask) != 0)
1246  cpu = sched_lowest(cg, mask, max(pri, PRI_MAX_TIMESHARE),
1247  INT_MAX, ts->ts_cpu);
1248  /* Search globally for the less loaded CPU we can run now. */
1249  if (cpu == -1)
1250  cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu);
1251  /* Search globally for the less loaded CPU. */
1252  if (cpu == -1)
1253  cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu);
1254  KASSERT(cpu != -1, ("sched_pickcpu: Failed to find a cpu."));
1255  /*
1256  * Compare the lowest loaded cpu to current cpu.
1257  */
1258  if (THREAD_CAN_SCHED(td, self) && TDQ_CPU(self)->tdq_lowpri > pri &&
1259  TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE &&
1260  TDQ_CPU(self)->tdq_load <= TDQ_CPU(cpu)->tdq_load + 1) {
1261  SCHED_STAT_INC(pickcpu_local);
1262  cpu = self;
1263  } else
1264  SCHED_STAT_INC(pickcpu_lowest);
1265  if (cpu != ts->ts_cpu)
1266  SCHED_STAT_INC(pickcpu_migration);
1267  return (cpu);
1268 }
1269 #endif
1270 
1271 /*
1272  * Pick the highest priority task we have and return it.
1273  */
1274 static struct thread *
1275 tdq_choose(struct tdq *tdq)
1276 {
1277  struct thread *td;
1278 
1279  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
1280  td = runq_choose(&tdq->tdq_realtime);
1281  if (td != NULL)
1282  return (td);
1283  td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
1284  if (td != NULL) {
1285  KASSERT(td->td_priority >= PRI_MIN_BATCH,
1286  ("tdq_choose: Invalid priority on timeshare queue %d",
1287  td->td_priority));
1288  return (td);
1289  }
1290  td = runq_choose(&tdq->tdq_idle);
1291  if (td != NULL) {
1292  KASSERT(td->td_priority >= PRI_MIN_IDLE,
1293  ("tdq_choose: Invalid priority on idle queue %d",
1294  td->td_priority));
1295  return (td);
1296  }
1297 
1298  return (NULL);
1299 }
1300 
1301 /*
1302  * Initialize a thread queue.
1303  */
1304 static void
1305 tdq_setup(struct tdq *tdq)
1306 {
1307 
1308  if (bootverbose)
1309  printf("ULE: setup cpu %d\n", TDQ_ID(tdq));
1310  runq_init(&tdq->tdq_realtime);
1311  runq_init(&tdq->tdq_timeshare);
1312  runq_init(&tdq->tdq_idle);
1313  snprintf(tdq->tdq_name, sizeof(tdq->tdq_name),
1314  "sched lock %d", (int)TDQ_ID(tdq));
1315  mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock",
1316  MTX_SPIN | MTX_RECURSE);
1317 #ifdef KTR
1318  snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname),
1319  "CPU %d load", (int)TDQ_ID(tdq));
1320 #endif
1321 }
1322 
1323 #ifdef SMP
1324 static void
1325 sched_setup_smp(void)
1326 {
1327  struct tdq *tdq;
1328  int i;
1329 
1330  cpu_top = smp_topo();
1331  CPU_FOREACH(i) {
1332  tdq = TDQ_CPU(i);
1333  tdq_setup(tdq);
1334  tdq->tdq_cg = smp_topo_find(cpu_top, i);
1335  if (tdq->tdq_cg == NULL)
1336  panic("Can't find cpu group for %d\n", i);
1337  }
1338  balance_tdq = TDQ_SELF();
1339  sched_balance();
1340 }
1341 #endif
1342 
1343 /*
1344  * Setup the thread queues and initialize the topology based on MD
1345  * information.
1346  */
1347 static void
1348 sched_setup(void *dummy)
1349 {
1350  struct tdq *tdq;
1351 
1352  tdq = TDQ_SELF();
1353 #ifdef SMP
1354  sched_setup_smp();
1355 #else
1356  tdq_setup(tdq);
1357 #endif
1358 
1359  /* Add thread0's load since it's running. */
1360  TDQ_LOCK(tdq);
1361  thread0.td_lock = TDQ_LOCKPTR(TDQ_SELF());
1362  tdq_load_add(tdq, &thread0);
1363  tdq->tdq_lowpri = thread0.td_priority;
1364  TDQ_UNLOCK(tdq);
1365 }
1366 
1367 /*
1368  * This routine determines time constants after stathz and hz are setup.
1369  */
1370 /* ARGSUSED */
1371 static void
1372 sched_initticks(void *dummy)
1373 {
1374  int incr;
1375 
1376  realstathz = stathz ? stathz : hz;
1377  sched_slice = realstathz / 10; /* ~100ms */
1378  hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
1379  realstathz);
1380 
1381  /*
1382  * tickincr is shifted out by 10 to avoid rounding errors due to
1383  * hz not being evenly divisible by stathz on all platforms.
1384  */
1385  incr = (hz << SCHED_TICK_SHIFT) / realstathz;
1386  /*
1387  * This does not work for values of stathz that are more than
1388  * 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
1389  */
1390  if (incr == 0)
1391  incr = 1;
1392  tickincr = incr;
1393 #ifdef SMP
1394  /*
1395  * Set the default balance interval now that we know
1396  * what realstathz is.
1397  */
1398  balance_interval = realstathz;
1399  affinity = SCHED_AFFINITY_DEFAULT;
1400 #endif
1401  if (sched_idlespinthresh < 0)
1402  sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz;
1403 }
1404 
1405 
1406 /*
1407  * This is the core of the interactivity algorithm. Determines a score based
1408  * on past behavior. It is the ratio of sleep time to run time scaled to
1409  * a [0, 100] integer. This is the voluntary sleep time of a process, which
1410  * differs from the cpu usage because it does not account for time spent
1411  * waiting on a run-queue. Would be prettier if we had floating point.
1412  */
1413 static int
1414 sched_interact_score(struct thread *td)
1415 {
1416  struct td_sched *ts;
1417  int div;
1418 
1419  ts = td->td_sched;
1420  /*
1421  * The score is only needed if this is likely to be an interactive
1422  * task. Don't go through the expense of computing it if there's
1423  * no chance.
1424  */
1425  if (sched_interact <= SCHED_INTERACT_HALF &&
1426  ts->ts_runtime >= ts->ts_slptime)
1427  return (SCHED_INTERACT_HALF);
1428 
1429  if (ts->ts_runtime > ts->ts_slptime) {
1430  div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF);
1431  return (SCHED_INTERACT_HALF +
1432  (SCHED_INTERACT_HALF - (ts->ts_slptime / div)));
1433  }
1434  if (ts->ts_slptime > ts->ts_runtime) {
1435  div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF);
1436  return (ts->ts_runtime / div);
1437  }
1438  /* runtime == slptime */
1439  if (ts->ts_runtime)
1440  return (SCHED_INTERACT_HALF);
1441 
1442  /*
1443  * This can happen if slptime and runtime are 0.
1444  */
1445  return (0);
1446 
1447 }
1448 
1449 /*
1450  * Scale the scheduling priority according to the "interactivity" of this
1451  * process.
1452  */
1453 static void
1454 sched_priority(struct thread *td)
1455 {
1456  int score;
1457  int pri;
1458 
1459  if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1460  return;
1461  /*
1462  * If the score is interactive we place the thread in the realtime
1463  * queue with a priority that is less than kernel and interrupt
1464  * priorities. These threads are not subject to nice restrictions.
1465  *
1466  * Scores greater than this are placed on the normal timeshare queue
1467  * where the priority is partially decided by the most recent cpu
1468  * utilization and the rest is decided by nice value.
1469  *
1470  * The nice value of the process has a linear effect on the calculated
1471  * score. Negative nice values make it easier for a thread to be
1472  * considered interactive.
1473  */
1474  score = imax(0, sched_interact_score(td) + td->td_proc->p_nice);
1475  if (score < sched_interact) {
1476  pri = PRI_MIN_INTERACT;
1477  pri += ((PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) /
1478  sched_interact) * score;
1479  KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT,
1480  ("sched_priority: invalid interactive priority %d score %d",
1481  pri, score));
1482  } else {
1483  pri = SCHED_PRI_MIN;
1484  if (td->td_sched->ts_ticks)
1485  pri += min(SCHED_PRI_TICKS(td->td_sched),
1486  SCHED_PRI_RANGE - 1);
1487  pri += SCHED_PRI_NICE(td->td_proc->p_nice);
1488  KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH,
1489  ("sched_priority: invalid priority %d: nice %d, "
1490  "ticks %d ftick %d ltick %d tick pri %d",
1491  pri, td->td_proc->p_nice, td->td_sched->ts_ticks,
1492  td->td_sched->ts_ftick, td->td_sched->ts_ltick,
1493  SCHED_PRI_TICKS(td->td_sched)));
1494  }
1495  sched_user_prio(td, pri);
1496 
1497  return;
1498 }
1499 
1500 /*
1501  * This routine enforces a maximum limit on the amount of scheduling history
1502  * kept. It is called after either the slptime or runtime is adjusted. This
1503  * function is ugly due to integer math.
1504  */
1505 static void
1506 sched_interact_update(struct thread *td)
1507 {
1508  struct td_sched *ts;
1509  u_int sum;
1510 
1511  ts = td->td_sched;
1512  sum = ts->ts_runtime + ts->ts_slptime;
1513  if (sum < SCHED_SLP_RUN_MAX)
1514  return;
1515  /*
1516  * This only happens from two places:
1517  * 1) We have added an unusual amount of run time from fork_exit.
1518  * 2) We have added an unusual amount of sleep time from sched_sleep().
1519  */
1520  if (sum > SCHED_SLP_RUN_MAX * 2) {
1521  if (ts->ts_runtime > ts->ts_slptime) {
1522  ts->ts_runtime = SCHED_SLP_RUN_MAX;
1523  ts->ts_slptime = 1;
1524  } else {
1525  ts->ts_slptime = SCHED_SLP_RUN_MAX;
1526  ts->ts_runtime = 1;
1527  }
1528  return;
1529  }
1530  /*
1531  * If we have exceeded by more than 1/5th then the algorithm below
1532  * will not bring us back into range. Dividing by two here forces
1533  * us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
1534  */
1535  if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) {
1536  ts->ts_runtime /= 2;
1537  ts->ts_slptime /= 2;
1538  return;
1539  }
1540  ts->ts_runtime = (ts->ts_runtime / 5) * 4;
1541  ts->ts_slptime = (ts->ts_slptime / 5) * 4;
1542 }
1543 
1544 /*
1545  * Scale back the interactivity history when a child thread is created. The
1546  * history is inherited from the parent but the thread may behave totally
1547  * differently. For example, a shell spawning a compiler process. We want
1548  * to learn that the compiler is behaving badly very quickly.
1549  */
1550 static void
1551 sched_interact_fork(struct thread *td)
1552 {
1553  int ratio;
1554  int sum;
1555 
1556  sum = td->td_sched->ts_runtime + td->td_sched->ts_slptime;
1557  if (sum > SCHED_SLP_RUN_FORK) {
1558  ratio = sum / SCHED_SLP_RUN_FORK;
1559  td->td_sched->ts_runtime /= ratio;
1560  td->td_sched->ts_slptime /= ratio;
1561  }
1562 }
1563 
1564 /*
1565  * Called from proc0_init() to setup the scheduler fields.
1566  */
1567 void
1568 schedinit(void)
1569 {
1570 
1571  /*
1572  * Set up the scheduler specific parts of proc0.
1573  */
1574  proc0.p_sched = NULL; /* XXX */
1575  thread0.td_sched = &td_sched0;
1576  td_sched0.ts_ltick = ticks;
1577  td_sched0.ts_ftick = ticks;
1578  td_sched0.ts_slice = sched_slice;
1579 }
1580 
1581 /*
1582  * This is only somewhat accurate since given many processes of the same
1583  * priority they will switch when their slices run out, which will be
1584  * at most sched_slice stathz ticks.
1585  */
1586 int
1587 sched_rr_interval(void)
1588 {
1589 
1590  /* Convert sched_slice from stathz to hz. */
1591  return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
1592 }
1593 
1594 /*
1595  * Update the percent cpu tracking information when it is requested or
1596  * the total history exceeds the maximum. We keep a sliding history of
1597  * tick counts that slowly decays. This is less precise than the 4BSD
1598  * mechanism since it happens with less regular and frequent events.
1599  */
1600 static void
1601 sched_pctcpu_update(struct td_sched *ts, int run)
1602 {
1603  int t = ticks;
1604 
1605  if (t - ts->ts_ltick >= SCHED_TICK_TARG) {
1606  ts->ts_ticks = 0;
1607  ts->ts_ftick = t - SCHED_TICK_TARG;
1608  } else if (t - ts->ts_ftick >= SCHED_TICK_MAX) {
1609  ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) *
1610  (ts->ts_ltick - (t - SCHED_TICK_TARG));
1611  ts->ts_ftick = t - SCHED_TICK_TARG;
1612  }
1613  if (run)
1614  ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT;
1615  ts->ts_ltick = t;
1616 }
1617 
1618 /*
1619  * Adjust the priority of a thread. Move it to the appropriate run-queue
1620  * if necessary. This is the back-end for several priority related
1621  * functions.
1622  */
1623 static void
1624 sched_thread_priority(struct thread *td, u_char prio)
1625 {
1626  struct td_sched *ts;
1627  struct tdq *tdq;
1628  int oldpri;
1629 
1630  KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio",
1631  "prio:%d", td->td_priority, "new prio:%d", prio,
1632  KTR_ATTR_LINKED, sched_tdname(curthread));
1633  SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
1634  if (td != curthread && prio < td->td_priority) {
1635  KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
1636  "lend prio", "prio:%d", td->td_priority, "new prio:%d",
1637  prio, KTR_ATTR_LINKED, sched_tdname(td));
1638  SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
1639  curthread);
1640  }
1641  ts = td->td_sched;
1642  THREAD_LOCK_ASSERT(td, MA_OWNED);
1643  if (td->td_priority == prio)
1644  return;
1645  /*
1646  * If the priority has been elevated due to priority
1647  * propagation, we may have to move ourselves to a new
1648  * queue. This could be optimized to not re-add in some
1649  * cases.
1650  */
1651  if (TD_ON_RUNQ(td) && prio < td->td_priority) {
1652  sched_rem(td);
1653  td->td_priority = prio;
1654  sched_add(td, SRQ_BORROWING);
1655  return;
1656  }
1657  /*
1658  * If the thread is currently running we may have to adjust the lowpri
1659  * information so other cpus are aware of our current priority.
1660  */
1661  if (TD_IS_RUNNING(td)) {
1662  tdq = TDQ_CPU(ts->ts_cpu);
1663  oldpri = td->td_priority;
1664  td->td_priority = prio;
1665  if (prio < tdq->tdq_lowpri)
1666  tdq->tdq_lowpri = prio;
1667  else if (tdq->tdq_lowpri == oldpri)
1668  tdq_setlowpri(tdq, td);
1669  return;
1670  }
1671  td->td_priority = prio;
1672 }
1673 
1674 /*
1675  * Update a thread's priority when it is lent another thread's
1676  * priority.
1677  */
1678 void
1679 sched_lend_prio(struct thread *td, u_char prio)
1680 {
1681 
1682  td->td_flags |= TDF_BORROWING;
1683  sched_thread_priority(td, prio);
1684 }
1685 
1686 /*
1687  * Restore a thread's priority when priority propagation is
1688  * over. The prio argument is the minimum priority the thread
1689  * needs to have to satisfy other possible priority lending
1690  * requests. If the thread's regular priority is less
1691  * important than prio, the thread will keep a priority boost
1692  * of prio.
1693  */
1694 void
1695 sched_unlend_prio(struct thread *td, u_char prio)
1696 {
1697  u_char base_pri;
1698 
1699  if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
1700  td->td_base_pri <= PRI_MAX_TIMESHARE)
1701  base_pri = td->td_user_pri;
1702  else
1703  base_pri = td->td_base_pri;
1704  if (prio >= base_pri) {
1705  td->td_flags &= ~TDF_BORROWING;
1706  sched_thread_priority(td, base_pri);
1707  } else
1708  sched_lend_prio(td, prio);
1709 }
1710 
1711 /*
1712  * Standard entry for setting the priority to an absolute value.
1713  */
1714 void
1715 sched_prio(struct thread *td, u_char prio)
1716 {
1717  u_char oldprio;
1718 
1719  /* First, update the base priority. */
1720  td->td_base_pri = prio;
1721 
1722  /*
1723  * If the thread is borrowing another thread's priority, don't
1724  * ever lower the priority.
1725  */
1726  if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
1727  return;
1728 
1729  /* Change the real priority. */
1730  oldprio = td->td_priority;
1731  sched_thread_priority(td, prio);
1732 
1733  /*
1734  * If the thread is on a turnstile, then let the turnstile update
1735  * its state.
1736  */
1737  if (TD_ON_LOCK(td) && oldprio != prio)
1738  turnstile_adjust(td, oldprio);
1739 }
1740 
1741 /*
1742  * Set the base user priority, does not effect current running priority.
1743  */
1744 void
1745 sched_user_prio(struct thread *td, u_char prio)
1746 {
1747 
1748  td->td_base_user_pri = prio;
1749  if (td->td_lend_user_pri <= prio)
1750  return;
1751  td->td_user_pri = prio;
1752 }
1753 
1754 void
1755 sched_lend_user_prio(struct thread *td, u_char prio)
1756 {
1757 
1758  THREAD_LOCK_ASSERT(td, MA_OWNED);
1759  td->td_lend_user_pri = prio;
1760  td->td_user_pri = min(prio, td->td_base_user_pri);
1761  if (td->td_priority > td->td_user_pri)
1762  sched_prio(td, td->td_user_pri);
1763  else if (td->td_priority != td->td_user_pri)
1764  td->td_flags |= TDF_NEEDRESCHED;
1765 }
1766 
1767 /*
1768  * Handle migration from sched_switch(). This happens only for
1769  * cpu binding.
1770  */
1771 static struct mtx *
1772 sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
1773 {
1774  struct tdq *tdn;
1775 
1776  tdn = TDQ_CPU(td->td_sched->ts_cpu);
1777 #ifdef SMP
1778  tdq_load_rem(tdq, td);
1779  /*
1780  * Do the lock dance required to avoid LOR. We grab an extra
1781  * spinlock nesting to prevent preemption while we're
1782  * not holding either run-queue lock.
1783  */
1784  spinlock_enter();
1785  thread_lock_block(td); /* This releases the lock on tdq. */
1786 
1787  /*
1788  * Acquire both run-queue locks before placing the thread on the new
1789  * run-queue to avoid deadlocks created by placing a thread with a
1790  * blocked lock on the run-queue of a remote processor. The deadlock
1791  * occurs when a third processor attempts to lock the two queues in
1792  * question while the target processor is spinning with its own
1793  * run-queue lock held while waiting for the blocked lock to clear.
1794  */
1795  tdq_lock_pair(tdn, tdq);
1796  tdq_add(tdn, td, flags);
1797  tdq_notify(tdn, td);
1798  TDQ_UNLOCK(tdn);
1799  spinlock_exit();
1800 #endif
1801  return (TDQ_LOCKPTR(tdn));
1802 }
1803 
1804 /*
1805  * Variadic version of thread_lock_unblock() that does not assume td_lock
1806  * is blocked.
1807  */
1808 static inline void
1809 thread_unblock_switch(struct thread *td, struct mtx *mtx)
1810 {
1811  atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock,
1812  (uintptr_t)mtx);
1813 }
1814 
1815 /*
1816  * Switch threads. This function has to handle threads coming in while
1817  * blocked for some reason, running, or idle. It also must deal with
1818  * migrating a thread from one queue to another as running threads may
1819  * be assigned elsewhere via binding.
1820  */
1821 void
1822 sched_switch(struct thread *td, struct thread *newtd, int flags)
1823 {
1824  struct tdq *tdq;
1825  struct td_sched *ts;
1826  struct mtx *mtx;
1827  int srqflag;
1828  int cpuid, preempted;
1829 
1830  THREAD_LOCK_ASSERT(td, MA_OWNED);
1831  KASSERT(newtd == NULL, ("sched_switch: Unsupported newtd argument"));
1832 
1833  cpuid = PCPU_GET(cpuid);
1834  tdq = TDQ_CPU(cpuid);
1835  ts = td->td_sched;
1836  mtx = td->td_lock;
1837  sched_pctcpu_update(ts, 1);
1838  ts->ts_rltick = ticks;
1839  td->td_lastcpu = td->td_oncpu;
1840  td->td_oncpu = NOCPU;
1841  preempted = !((td->td_flags & TDF_SLICEEND) ||
1842  (flags & SWT_RELINQUISH));
1843  td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND);
1844  td->td_owepreempt = 0;
1845  if (!TD_IS_IDLETHREAD(td))
1846  tdq->tdq_switchcnt++;
1847  /*
1848  * The lock pointer in an idle thread should never change. Reset it
1849  * to CAN_RUN as well.
1850  */
1851  if (TD_IS_IDLETHREAD(td)) {
1852  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1853  TD_SET_CAN_RUN(td);
1854  } else if (TD_IS_RUNNING(td)) {
1855  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1856  srqflag = preempted ?
1857  SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
1858  SRQ_OURSELF|SRQ_YIELDING;
1859 #ifdef SMP
1860  if (THREAD_CAN_MIGRATE(td) && !THREAD_CAN_SCHED(td, ts->ts_cpu))
1861  ts->ts_cpu = sched_pickcpu(td, 0);
1862 #endif
1863  if (ts->ts_cpu == cpuid)
1864  tdq_runq_add(tdq, td, srqflag);
1865  else {
1866  KASSERT(THREAD_CAN_MIGRATE(td) ||
1867  (ts->ts_flags & TSF_BOUND) != 0,
1868  ("Thread %p shouldn't migrate", td));
1869  mtx = sched_switch_migrate(tdq, td, srqflag);
1870  }
1871  } else {
1872  /* This thread must be going to sleep. */
1873  TDQ_LOCK(tdq);
1874  mtx = thread_lock_block(td);
1875  tdq_load_rem(tdq, td);
1876  }
1877  /*
1878  * We enter here with the thread blocked and assigned to the
1879  * appropriate cpu run-queue or sleep-queue and with the current
1880  * thread-queue locked.
1881  */
1882  TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
1883  newtd = choosethread();
1884  /*
1885  * Call the MD code to switch contexts if necessary.
1886  */
1887  if (td != newtd) {
1888 #ifdef HWPMC_HOOKS
1889  if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1890  PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
1891 #endif
1892  SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
1893  lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
1894  TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
1895  sched_pctcpu_update(newtd->td_sched, 0);
1896 
1897 #ifdef KDTRACE_HOOKS
1898  /*
1899  * If DTrace has set the active vtime enum to anything
1900  * other than INACTIVE (0), then it should have set the
1901  * function to call.
1902  */
1903  if (dtrace_vtime_active)
1904  (*dtrace_vtime_switch_func)(newtd);
1905 #endif
1906 
1907  cpu_switch(td, newtd, mtx);
1908  /*
1909  * We may return from cpu_switch on a different cpu. However,
1910  * we always return with td_lock pointing to the current cpu's
1911  * run queue lock.
1912  */
1913  cpuid = PCPU_GET(cpuid);
1914  tdq = TDQ_CPU(cpuid);
1915  lock_profile_obtain_lock_success(
1916  &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
1917 
1918  SDT_PROBE0(sched, , , on__cpu);
1919 #ifdef HWPMC_HOOKS
1920  if (PMC_PROC_IS_USING_PMCS(td->td_proc))
1921  PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
1922 #endif
1923  } else {
1924  thread_unblock_switch(td, mtx);
1925  SDT_PROBE0(sched, , , remain__cpu);
1926  }
1927  /*
1928  * Assert that all went well and return.
1929  */
1930  TDQ_LOCK_ASSERT(tdq, MA_OWNED|MA_NOTRECURSED);
1931  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
1932  td->td_oncpu = cpuid;
1933 }
1934 
1935 /*
1936  * Adjust thread priorities as a result of a nice request.
1937  */
1938 void
1939 sched_nice(struct proc *p, int nice)
1940 {
1941  struct thread *td;
1942 
1943  PROC_LOCK_ASSERT(p, MA_OWNED);
1944 
1945  p->p_nice = nice;
1946  FOREACH_THREAD_IN_PROC(p, td) {
1947  thread_lock(td);
1948  sched_priority(td);
1949  sched_prio(td, td->td_base_user_pri);
1950  thread_unlock(td);
1951  }
1952 }
1953 
1954 /*
1955  * Record the sleep time for the interactivity scorer.
1956  */
1957 void
1958 sched_sleep(struct thread *td, int prio)
1959 {
1960 
1961  THREAD_LOCK_ASSERT(td, MA_OWNED);
1962 
1963  td->td_slptick = ticks;
1964  if (TD_IS_SUSPENDED(td) || prio >= PSOCK)
1965  td->td_flags |= TDF_CANSWAP;
1966  if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
1967  return;
1968  if (static_boost == 1 && prio)
1969  sched_prio(td, prio);
1970  else if (static_boost && td->td_priority > static_boost)
1971  sched_prio(td, static_boost);
1972 }
1973 
1974 /*
1975  * Schedule a thread to resume execution and record how long it voluntarily
1976  * slept. We also update the pctcpu, interactivity, and priority.
1977  */
1978 void
1979 sched_wakeup(struct thread *td)
1980 {
1981  struct td_sched *ts;
1982  int slptick;
1983 
1984  THREAD_LOCK_ASSERT(td, MA_OWNED);
1985  ts = td->td_sched;
1986  td->td_flags &= ~TDF_CANSWAP;
1987  /*
1988  * If we slept for more than a tick update our interactivity and
1989  * priority.
1990  */
1991  slptick = td->td_slptick;
1992  td->td_slptick = 0;
1993  if (slptick && slptick != ticks) {
1994  ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT;
1995  sched_interact_update(td);
1996  sched_pctcpu_update(ts, 0);
1997  }
1998  /* Reset the slice value after we sleep. */
1999  ts->ts_slice = sched_slice;
2000  sched_add(td, SRQ_BORING);
2001 }
2002 
2003 /*
2004  * Penalize the parent for creating a new child and initialize the child's
2005  * priority.
2006  */
2007 void
2008 sched_fork(struct thread *td, struct thread *child)
2009 {
2010  THREAD_LOCK_ASSERT(td, MA_OWNED);
2011  sched_pctcpu_update(td->td_sched, 1);
2012  sched_fork_thread(td, child);
2013  /*
2014  * Penalize the parent and child for forking.
2015  */
2016  sched_interact_fork(child);
2017  sched_priority(child);
2018  td->td_sched->ts_runtime += tickincr;
2019  sched_interact_update(td);
2020  sched_priority(td);
2021 }
2022 
2023 /*
2024  * Fork a new thread, may be within the same process.
2025  */
2026 void
2027 sched_fork_thread(struct thread *td, struct thread *child)
2028 {
2029  struct td_sched *ts;
2030  struct td_sched *ts2;
2031 
2032  THREAD_LOCK_ASSERT(td, MA_OWNED);
2033  /*
2034  * Initialize child.
2035  */
2036  ts = td->td_sched;
2037  ts2 = child->td_sched;
2038  child->td_oncpu = NOCPU;
2039  child->td_lastcpu = NOCPU;
2040  child->td_lock = TDQ_LOCKPTR(TDQ_SELF());
2041  child->td_cpuset = cpuset_ref(td->td_cpuset);
2042  ts2->ts_cpu = ts->ts_cpu;
2043  ts2->ts_flags = 0;
2044  /*
2045  * Grab our parents cpu estimation information.
2046  */
2047  ts2->ts_ticks = ts->ts_ticks;
2048  ts2->ts_ltick = ts->ts_ltick;
2049  ts2->ts_ftick = ts->ts_ftick;
2050  /*
2051  * Do not inherit any borrowed priority from the parent.
2052  */
2053  child->td_priority = child->td_base_pri;
2054  /*
2055  * And update interactivity score.
2056  */
2057  ts2->ts_slptime = ts->ts_slptime;
2058  ts2->ts_runtime = ts->ts_runtime;
2059  ts2->ts_slice = 1; /* Attempt to quickly learn interactivity. */
2060 #ifdef KTR
2061  bzero(ts2->ts_name, sizeof(ts2->ts_name));
2062 #endif
2063 }
2064 
2065 /*
2066  * Adjust the priority class of a thread.
2067  */
2068 void
2069 sched_class(struct thread *td, int class)
2070 {
2071 
2072  THREAD_LOCK_ASSERT(td, MA_OWNED);
2073  if (td->td_pri_class == class)
2074  return;
2075  td->td_pri_class = class;
2076 }
2077 
2078 /*
2079  * Return some of the child's priority and interactivity to the parent.
2080  */
2081 void
2082 sched_exit(struct proc *p, struct thread *child)
2083 {
2084  struct thread *td;
2085 
2086  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit",
2087  "prio:%d", child->td_priority);
2088  PROC_LOCK_ASSERT(p, MA_OWNED);
2089  td = FIRST_THREAD_IN_PROC(p);
2090  sched_exit_thread(td, child);
2091 }
2092 
2093 /*
2094  * Penalize another thread for the time spent on this one. This helps to
2095  * worsen the priority and interactivity of processes which schedule batch
2096  * jobs such as make. This has little effect on the make process itself but
2097  * causes new processes spawned by it to receive worse scores immediately.
2098  */
2099 void
2100 sched_exit_thread(struct thread *td, struct thread *child)
2101 {
2102 
2103  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit",
2104  "prio:%d", child->td_priority);
2105  /*
2106  * Give the child's runtime to the parent without returning the
2107  * sleep time as a penalty to the parent. This causes shells that
2108  * launch expensive things to mark their children as expensive.
2109  */
2110  thread_lock(td);
2111  td->td_sched->ts_runtime += child->td_sched->ts_runtime;
2112  sched_interact_update(td);
2113  sched_priority(td);
2114  thread_unlock(td);
2115 }
2116 
2117 void
2118 sched_preempt(struct thread *td)
2119 {
2120  struct tdq *tdq;
2121 
2122  SDT_PROBE2(sched, , , surrender, td, td->td_proc);
2123 
2124  thread_lock(td);
2125  tdq = TDQ_SELF();
2126  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2127  tdq->tdq_ipipending = 0;
2128  if (td->td_priority > tdq->tdq_lowpri) {
2129  int flags;
2130 
2131  flags = SW_INVOL | SW_PREEMPT;
2132  if (td->td_critnest > 1)
2133  td->td_owepreempt = 1;
2134  else if (TD_IS_IDLETHREAD(td))
2135  mi_switch(flags | SWT_REMOTEWAKEIDLE, NULL);
2136  else
2137  mi_switch(flags | SWT_REMOTEPREEMPT, NULL);
2138  }
2139  thread_unlock(td);
2140 }
2141 
2142 /*
2143  * Fix priorities on return to user-space. Priorities may be elevated due
2144  * to static priorities in msleep() or similar.
2145  */
2146 void
2147 sched_userret(struct thread *td)
2148 {
2149  /*
2150  * XXX we cheat slightly on the locking here to avoid locking in
2151  * the usual case. Setting td_priority here is essentially an
2152  * incomplete workaround for not setting it properly elsewhere.
2153  * Now that some interrupt handlers are threads, not setting it
2154  * properly elsewhere can clobber it in the window between setting
2155  * it here and returning to user mode, so don't waste time setting
2156  * it perfectly here.
2157  */
2158  KASSERT((td->td_flags & TDF_BORROWING) == 0,
2159  ("thread with borrowed priority returning to userland"));
2160  if (td->td_priority != td->td_user_pri) {
2161  thread_lock(td);
2162  td->td_priority = td->td_user_pri;
2163  td->td_base_pri = td->td_user_pri;
2164  tdq_setlowpri(TDQ_SELF(), td);
2165  thread_unlock(td);
2166  }
2167 }
2168 
2169 /*
2170  * Handle a stathz tick. This is really only relevant for timeshare
2171  * threads.
2172  */
2173 void
2174 sched_clock(struct thread *td)
2175 {
2176  struct tdq *tdq;
2177  struct td_sched *ts;
2178 
2179  THREAD_LOCK_ASSERT(td, MA_OWNED);
2180  tdq = TDQ_SELF();
2181 #ifdef SMP
2182  /*
2183  * We run the long term load balancer infrequently on the first cpu.
2184  */
2185  if (balance_tdq == tdq) {
2186  if (balance_ticks && --balance_ticks == 0)
2187  sched_balance();
2188  }
2189 #endif
2190  /*
2191  * Save the old switch count so we have a record of the last ticks
2192  * activity. Initialize the new switch count based on our load.
2193  * If there is some activity seed it to reflect that.
2194  */
2195  tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt;
2196  tdq->tdq_switchcnt = tdq->tdq_load;
2197  /*
2198  * Advance the insert index once for each tick to ensure that all
2199  * threads get a chance to run.
2200  */
2201  if (tdq->tdq_idx == tdq->tdq_ridx) {
2202  tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
2203  if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
2204  tdq->tdq_ridx = tdq->tdq_idx;
2205  }
2206  ts = td->td_sched;
2207  sched_pctcpu_update(ts, 1);
2208  if (td->td_pri_class & PRI_FIFO_BIT)
2209  return;
2210  if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) {
2211  /*
2212  * We used a tick; charge it to the thread so
2213  * that we can compute our interactivity.
2214  */
2215  td->td_sched->ts_runtime += tickincr;
2216  sched_interact_update(td);
2217  sched_priority(td);
2218  }
2219 
2220  /*
2221  * Force a context switch if the current thread has used up a full
2222  * time slice (default is 100ms).
2223  */
2224  if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) {
2225  ts->ts_slice = sched_slice;
2226  td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
2227  }
2228 }
2229 
2230 /*
2231  * Called once per hz tick.
2232  */
2233 void
2234 sched_tick(int cnt)
2235 {
2236 
2237 }
2238 
2239 /*
2240  * Return whether the current CPU has runnable tasks. Used for in-kernel
2241  * cooperative idle threads.
2242  */
2243 int
2244 sched_runnable(void)
2245 {
2246  struct tdq *tdq;
2247  int load;
2248 
2249  load = 1;
2250 
2251  tdq = TDQ_SELF();
2252  if ((curthread->td_flags & TDF_IDLETD) != 0) {
2253  if (tdq->tdq_load > 0)
2254  goto out;
2255  } else
2256  if (tdq->tdq_load - 1 > 0)
2257  goto out;
2258  load = 0;
2259 out:
2260  return (load);
2261 }
2262 
2263 /*
2264  * Choose the highest priority thread to run. The thread is removed from
2265  * the run-queue while running however the load remains. For SMP we set
2266  * the tdq in the global idle bitmask if it idles here.
2267  */
2268 struct thread *
2269 sched_choose(void)
2270 {
2271  struct thread *td;
2272  struct tdq *tdq;
2273 
2274  tdq = TDQ_SELF();
2275  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2276  td = tdq_choose(tdq);
2277  if (td) {
2278  tdq_runq_rem(tdq, td);
2279  tdq->tdq_lowpri = td->td_priority;
2280  return (td);
2281  }
2282  tdq->tdq_lowpri = PRI_MAX_IDLE;
2283  return (PCPU_GET(idlethread));
2284 }
2285 
2286 /*
2287  * Set owepreempt if necessary. Preemption never happens directly in ULE,
2288  * we always request it once we exit a critical section.
2289  */
2290 static inline void
2291 sched_setpreempt(struct thread *td)
2292 {
2293  struct thread *ctd;
2294  int cpri;
2295  int pri;
2296 
2297  THREAD_LOCK_ASSERT(curthread, MA_OWNED);
2298 
2299  ctd = curthread;
2300  pri = td->td_priority;
2301  cpri = ctd->td_priority;
2302  if (pri < cpri)
2303  ctd->td_flags |= TDF_NEEDRESCHED;
2304  if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
2305  return;
2306  if (!sched_shouldpreempt(pri, cpri, 0))
2307  return;
2308  ctd->td_owepreempt = 1;
2309 }
2310 
2311 /*
2312  * Add a thread to a thread queue. Select the appropriate runq and add the
2313  * thread to it. This is the internal function called when the tdq is
2314  * predetermined.
2315  */
2316 void
2317 tdq_add(struct tdq *tdq, struct thread *td, int flags)
2318 {
2319 
2320  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2321  KASSERT((td->td_inhibitors == 0),
2322  ("sched_add: trying to run inhibited thread"));
2323  KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
2324  ("sched_add: bad thread state"));
2325  KASSERT(td->td_flags & TDF_INMEM,
2326  ("sched_add: thread swapped out"));
2327 
2328  if (td->td_priority < tdq->tdq_lowpri)
2329  tdq->tdq_lowpri = td->td_priority;
2330  tdq_runq_add(tdq, td, flags);
2331  tdq_load_add(tdq, td);
2332 }
2333 
2334 /*
2335  * Select the target thread queue and add a thread to it. Request
2336  * preemption or IPI a remote processor if required.
2337  */
2338 void
2339 sched_add(struct thread *td, int flags)
2340 {
2341  struct tdq *tdq;
2342 #ifdef SMP
2343  int cpu;
2344 #endif
2345 
2346  KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
2347  "prio:%d", td->td_priority, KTR_ATTR_LINKED,
2348  sched_tdname(curthread));
2349  KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
2350  KTR_ATTR_LINKED, sched_tdname(td));
2351  SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
2352  flags & SRQ_PREEMPTED);
2353  THREAD_LOCK_ASSERT(td, MA_OWNED);
2354  /*
2355  * Recalculate the priority before we select the target cpu or
2356  * run-queue.
2357  */
2358  if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
2359  sched_priority(td);
2360 #ifdef SMP
2361  /*
2362  * Pick the destination cpu and if it isn't ours transfer to the
2363  * target cpu.
2364  */
2365  cpu = sched_pickcpu(td, flags);
2366  tdq = sched_setcpu(td, cpu, flags);
2367  tdq_add(tdq, td, flags);
2368  if (cpu != PCPU_GET(cpuid)) {
2369  tdq_notify(tdq, td);
2370  return;
2371  }
2372 #else
2373  tdq = TDQ_SELF();
2374  TDQ_LOCK(tdq);
2375  /*
2376  * Now that the thread is moving to the run-queue, set the lock
2377  * to the scheduler's lock.
2378  */
2379  thread_lock_set(td, TDQ_LOCKPTR(tdq));
2380  tdq_add(tdq, td, flags);
2381 #endif
2382  if (!(flags & SRQ_YIELDING))
2383  sched_setpreempt(td);
2384 }
2385 
2386 /*
2387  * Remove a thread from a run-queue without running it. This is used
2388  * when we're stealing a thread from a remote queue. Otherwise all threads
2389  * exit by calling sched_exit_thread() and sched_throw() themselves.
2390  */
2391 void
2392 sched_rem(struct thread *td)
2393 {
2394  struct tdq *tdq;
2395 
2396  KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
2397  "prio:%d", td->td_priority);
2398  SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
2399  tdq = TDQ_CPU(td->td_sched->ts_cpu);
2400  TDQ_LOCK_ASSERT(tdq, MA_OWNED);
2401  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2402  KASSERT(TD_ON_RUNQ(td),
2403  ("sched_rem: thread not on run queue"));
2404  tdq_runq_rem(tdq, td);
2405  tdq_load_rem(tdq, td);
2406  TD_SET_CAN_RUN(td);
2407  if (td->td_priority == tdq->tdq_lowpri)
2408  tdq_setlowpri(tdq, NULL);
2409 }
2410 
2411 /*
2412  * Fetch cpu utilization information. Updates on demand.
2413  */
2414 fixpt_t
2415 sched_pctcpu(struct thread *td)
2416 {
2417  fixpt_t pctcpu;
2418  struct td_sched *ts;
2419 
2420  pctcpu = 0;
2421  ts = td->td_sched;
2422  if (ts == NULL)
2423  return (0);
2424 
2425  THREAD_LOCK_ASSERT(td, MA_OWNED);
2426  sched_pctcpu_update(ts, TD_IS_RUNNING(td));
2427  if (ts->ts_ticks) {
2428  int rtick;
2429 
2430  /* How many rtick per second ? */
2431  rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
2432  pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
2433  }
2434 
2435  return (pctcpu);
2436 }
2437 
2438 /*
2439  * Enforce affinity settings for a thread. Called after adjustments to
2440  * cpumask.
2441  */
2442 void
2443 sched_affinity(struct thread *td)
2444 {
2445 #ifdef SMP
2446  struct td_sched *ts;
2447 
2448  THREAD_LOCK_ASSERT(td, MA_OWNED);
2449  ts = td->td_sched;
2450  if (THREAD_CAN_SCHED(td, ts->ts_cpu))
2451  return;
2452  if (TD_ON_RUNQ(td)) {
2453  sched_rem(td);
2454  sched_add(td, SRQ_BORING);
2455  return;
2456  }
2457  if (!TD_IS_RUNNING(td))
2458  return;
2459  /*
2460  * Force a switch before returning to userspace. If the
2461  * target thread is not running locally send an ipi to force
2462  * the issue.
2463  */
2464  td->td_flags |= TDF_NEEDRESCHED;
2465  if (td != curthread)
2466  ipi_cpu(ts->ts_cpu, IPI_PREEMPT);
2467 #endif
2468 }
2469 
2470 /*
2471  * Bind a thread to a target cpu.
2472  */
2473 void
2474 sched_bind(struct thread *td, int cpu)
2475 {
2476  struct td_sched *ts;
2477 
2478  THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
2479  KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
2480  ts = td->td_sched;
2481  if (ts->ts_flags & TSF_BOUND)
2482  sched_unbind(td);
2483  KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td));
2484  ts->ts_flags |= TSF_BOUND;
2485  sched_pin();
2486  if (PCPU_GET(cpuid) == cpu)
2487  return;
2488  ts->ts_cpu = cpu;
2489  /* When we return from mi_switch we'll be on the correct cpu. */
2490  mi_switch(SW_VOL, NULL);
2491 }
2492 
2493 /*
2494  * Release a bound thread.
2495  */
2496 void
2497 sched_unbind(struct thread *td)
2498 {
2499  struct td_sched *ts;
2500 
2501  THREAD_LOCK_ASSERT(td, MA_OWNED);
2502  KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
2503  ts = td->td_sched;
2504  if ((ts->ts_flags & TSF_BOUND) == 0)
2505  return;
2506  ts->ts_flags &= ~TSF_BOUND;
2507  sched_unpin();
2508 }
2509 
2510 int
2511 sched_is_bound(struct thread *td)
2512 {
2513  THREAD_LOCK_ASSERT(td, MA_OWNED);
2514  return (td->td_sched->ts_flags & TSF_BOUND);
2515 }
2516 
2517 /*
2518  * Basic yield call.
2519  */
2520 void
2521 sched_relinquish(struct thread *td)
2522 {
2523  thread_lock(td);
2524  mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
2525  thread_unlock(td);
2526 }
2527 
2528 /*
2529  * Return the total system load.
2530  */
2531 int
2532 sched_load(void)
2533 {
2534 #ifdef SMP
2535  int total;
2536  int i;
2537 
2538  total = 0;
2539  CPU_FOREACH(i)
2540  total += TDQ_CPU(i)->tdq_sysload;
2541  return (total);
2542 #else
2543  return (TDQ_SELF()->tdq_sysload);
2544 #endif
2545 }
2546 
2547 int
2548 sched_sizeof_proc(void)
2549 {
2550  return (sizeof(struct proc));
2551 }
2552 
2553 int
2554 sched_sizeof_thread(void)
2555 {
2556  return (sizeof(struct thread) + sizeof(struct td_sched));
2557 }
2558 
2559 #ifdef SMP
2560 #define TDQ_IDLESPIN(tdq) \
2561  ((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0)
2562 #else
2563 #define TDQ_IDLESPIN(tdq) 1
2564 #endif
2565 
2566 /*
2567  * The actual idle process.
2568  */
2569 void
2570 sched_idletd(void *dummy)
2571 {
2572  struct thread *td;
2573  struct tdq *tdq;
2574  int oldswitchcnt, switchcnt;
2575  int i;
2576 
2577  mtx_assert(&Giant, MA_NOTOWNED);
2578  td = curthread;
2579  tdq = TDQ_SELF();
2580  oldswitchcnt = -1;
2581  for (;;) {
2582  if (tdq->tdq_load) {
2583  thread_lock(td);
2584  mi_switch(SW_VOL | SWT_IDLE, NULL);
2585  thread_unlock(td);
2586  }
2587  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2588 #ifdef SMP
2589  if (switchcnt != oldswitchcnt) {
2590  oldswitchcnt = switchcnt;
2591  if (tdq_idled(tdq) == 0)
2592  continue;
2593  }
2594  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2595 #else
2596  oldswitchcnt = switchcnt;
2597 #endif
2598  /*
2599  * If we're switching very frequently, spin while checking
2600  * for load rather than entering a low power state that
2601  * may require an IPI. However, don't do any busy
2602  * loops while on SMT machines as this simply steals
2603  * cycles from cores doing useful work.
2604  */
2605  if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) {
2606  for (i = 0; i < sched_idlespins; i++) {
2607  if (tdq->tdq_load)
2608  break;
2609  cpu_spinwait();
2610  }
2611  }
2612 
2613  /* If there was context switch during spin, restart it. */
2614  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2615  if (tdq->tdq_load != 0 || switchcnt != oldswitchcnt)
2616  continue;
2617 
2618  /* Run main MD idle handler. */
2619  tdq->tdq_cpu_idle = 1;
2620  /*
2621  * Make sure that tdq_cpu_idle update is globally visible
2622  * before cpu_idle() read tdq_load. The order is important
2623  * to avoid race with tdq_notify.
2624  */
2625  mb();
2626  cpu_idle(switchcnt * 4 > sched_idlespinthresh);
2627  tdq->tdq_cpu_idle = 0;
2628 
2629  /*
2630  * Account thread-less hardware interrupts and
2631  * other wakeup reasons equal to context switches.
2632  */
2633  switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt;
2634  if (switchcnt != oldswitchcnt)
2635  continue;
2636  tdq->tdq_switchcnt++;
2637  oldswitchcnt++;
2638  }
2639 }
2640 
2641 /*
2642  * A CPU is entering for the first time or a thread is exiting.
2643  */
2644 void
2645 sched_throw(struct thread *td)
2646 {
2647  struct thread *newtd;
2648  struct tdq *tdq;
2649 
2650  tdq = TDQ_SELF();
2651  if (td == NULL) {
2652  /* Correct spinlock nesting and acquire the correct lock. */
2653  TDQ_LOCK(tdq);
2654  spinlock_exit();
2655  PCPU_SET(switchtime, cpu_ticks());
2656  PCPU_SET(switchticks, ticks);
2657  } else {
2658  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2659  tdq_load_rem(tdq, td);
2660  lock_profile_release_lock(&TDQ_LOCKPTR(tdq)->lock_object);
2661  td->td_lastcpu = td->td_oncpu;
2662  td->td_oncpu = NOCPU;
2663  }
2664  KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
2665  newtd = choosethread();
2666  TDQ_LOCKPTR(tdq)->mtx_lock = (uintptr_t)newtd;
2667  cpu_throw(td, newtd); /* doesn't return */
2668 }
2669 
2670 /*
2671  * This is called from fork_exit(). Just acquire the correct locks and
2672  * let fork do the rest of the work.
2673  */
2674 void
2675 sched_fork_exit(struct thread *td)
2676 {
2677  struct td_sched *ts;
2678  struct tdq *tdq;
2679  int cpuid;
2680 
2681  /*
2682  * Finish setting up thread glue so that it begins execution in a
2683  * non-nested critical section with the scheduler lock held.
2684  */
2685  cpuid = PCPU_GET(cpuid);
2686  tdq = TDQ_CPU(cpuid);
2687  ts = td->td_sched;
2688  if (TD_IS_IDLETHREAD(td))
2689  td->td_lock = TDQ_LOCKPTR(tdq);
2690  MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
2691  td->td_oncpu = cpuid;
2692  TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
2693  lock_profile_obtain_lock_success(
2694  &TDQ_LOCKPTR(tdq)->lock_object, 0, 0, __FILE__, __LINE__);
2695 }
2696 
2697 /*
2698  * Create on first use to catch odd startup conditons.
2699  */
2700 char *
2701 sched_tdname(struct thread *td)
2702 {
2703 #ifdef KTR
2704  struct td_sched *ts;
2705 
2706  ts = td->td_sched;
2707  if (ts->ts_name[0] == '\0')
2708  snprintf(ts->ts_name, sizeof(ts->ts_name),
2709  "%s tid %d", td->td_name, td->td_tid);
2710  return (ts->ts_name);
2711 #else
2712  return (td->td_name);
2713 #endif
2714 }
2715 
2716 #ifdef KTR
2717 void
2718 sched_clear_tdname(struct thread *td)
2719 {
2720  struct td_sched *ts;
2721 
2722  ts = td->td_sched;
2723  ts->ts_name[0] = '\0';
2724 }
2725 #endif
2726 
2727 #ifdef SMP
2728 
2729 /*
2730  * Build the CPU topology dump string. Is recursively called to collect
2731  * the topology tree.
2732  */
2733 static int
2734 sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg,
2735  int indent)
2736 {
2737  char cpusetbuf[CPUSETBUFSIZ];
2738  int i, first;
2739 
2740  sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent,
2741  "", 1 + indent / 2, cg->cg_level);
2742  sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "",
2743  cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask));
2744  first = TRUE;
2745  for (i = 0; i < MAXCPU; i++) {
2746  if (CPU_ISSET(i, &cg->cg_mask)) {
2747  if (!first)
2748  sbuf_printf(sb, ", ");
2749  else
2750  first = FALSE;
2751  sbuf_printf(sb, "%d", i);
2752  }
2753  }
2754  sbuf_printf(sb, "</cpu>\n");
2755 
2756  if (cg->cg_flags != 0) {
2757  sbuf_printf(sb, "%*s <flags>", indent, "");
2758  if ((cg->cg_flags & CG_FLAG_HTT) != 0)
2759  sbuf_printf(sb, "<flag name=\"HTT\">HTT group</flag>");
2760  if ((cg->cg_flags & CG_FLAG_THREAD) != 0)
2761  sbuf_printf(sb, "<flag name=\"THREAD\">THREAD group</flag>");
2762  if ((cg->cg_flags & CG_FLAG_SMT) != 0)
2763  sbuf_printf(sb, "<flag name=\"SMT\">SMT group</flag>");
2764  sbuf_printf(sb, "</flags>\n");
2765  }
2766 
2767  if (cg->cg_children > 0) {
2768  sbuf_printf(sb, "%*s <children>\n", indent, "");
2769  for (i = 0; i < cg->cg_children; i++)
2770  sysctl_kern_sched_topology_spec_internal(sb,
2771  &cg->cg_child[i], indent+2);
2772  sbuf_printf(sb, "%*s </children>\n", indent, "");
2773  }
2774  sbuf_printf(sb, "%*s</group>\n", indent, "");
2775  return (0);
2776 }
2777 
2778 /*
2779  * Sysctl handler for retrieving topology dump. It's a wrapper for
2780  * the recursive sysctl_kern_smp_topology_spec_internal().
2781  */
2782 static int
2783 sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
2784 {
2785  struct sbuf *topo;
2786  int err;
2787 
2788  KASSERT(cpu_top != NULL, ("cpu_top isn't initialized"));
2789 
2790  topo = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND);
2791  if (topo == NULL)
2792  return (ENOMEM);
2793 
2794  sbuf_printf(topo, "<groups>\n");
2795  err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1);
2796  sbuf_printf(topo, "</groups>\n");
2797 
2798  if (err == 0) {
2799  sbuf_finish(topo);
2800  err = SYSCTL_OUT(req, sbuf_data(topo), sbuf_len(topo));
2801  }
2802  sbuf_delete(topo);
2803  return (err);
2804 }
2805 
2806 #endif
2807 
2808 static int
2809 sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
2810 {
2811  int error, new_val, period;
2812 
2813  period = 1000000 / realstathz;
2814  new_val = period * sched_slice;
2815  error = sysctl_handle_int(oidp, &new_val, 0, req);
2816  if (error != 0 || req->newptr == NULL)
2817  return (error);
2818  if (new_val <= 0)
2819  return (EINVAL);
2820  sched_slice = imax(1, (new_val + period / 2) / period);
2821  hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
2822  realstathz);
2823  return (0);
2824 }
2825 
2826 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler");
2827 SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
2828  "Scheduler name");
2829 SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
2830  NULL, 0, sysctl_kern_quantum, "I",
2831  "Quantum for timeshare threads in microseconds");
2832 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
2833  "Quantum for timeshare threads in stathz ticks");
2834 SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
2835  "Interactivity score threshold");
2836 SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW,
2837  &preempt_thresh, 0,
2838  "Maximal (lowest) priority for preemption");
2839 SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0,
2840  "Assign static kernel priorities to sleeping threads");
2841 SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0,
2842  "Number of times idle thread will spin waiting for new work");
2843 SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW,
2844  &sched_idlespinthresh, 0,
2845  "Threshold before we will permit idle thread spinning");
2846 #ifdef SMP
2847 SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
2848  "Number of hz ticks to keep thread affinity for");
2849 SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
2850  "Enables the long-term load balancer");
2851 SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
2852  &balance_interval, 0,
2853  "Average period in stathz ticks to run the long-term balancer");
2854 SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
2855  "Attempts to steal work from other cores before idling");
2856 SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
2857  "Minimum load on remote CPU before we'll steal");
2858 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
2859  CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A",
2860  "XML dump of detected CPU topology");
2861 #endif
2862 
2863 /* ps compat. All cpu percentages from ULE are weighted. */
2864 static int ccpu = 0;
2865 SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
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Definition: sched_ule.c:2675
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Definition: kern_cpuset.c:121
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Definition: sched_ule.c:113
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Definition: sched_ule.c:130
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Definition: sched_ule.c:2443
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Definition: sched_ule.c:169
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Definition: sched_ule.c:288
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Definition: sched_ule.c:231
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Definition: sched_ule.c:110
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Definition: sched_ule.c:229
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Definition: sched_ule.c:287
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Definition: sched_ule.c:289
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Definition: sched_ule.c:2532
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Definition: kern_synch.c:87
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Definition: sched_ule.c:203
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Definition: sched_ule.c:1551
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Definition: kern_clock.c:384
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Definition: sched_ule.c:1454
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Definition: sched_ule.c:1939
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Definition: sched_ule.c:186
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Definition: sched_ule.c:2291
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Definition: sched_ule.c:232
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Definition: sched_ule.c:206
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Definition: sched_ule.c:2147
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Definition: sched_ule.c:290
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Definition: sched_ule.c:2008
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Definition: sched_ule.c:190
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Definition: sched_ule.c:133
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Definition: sched_ule.c:146
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Definition: sched_ule.c:2244
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Definition: sched_ule.c:214
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Definition: sched_ule.c:128
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Definition: sched_ule.c:115
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Definition: sched_ule.c:1715
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Definition: sched_ule.c:228
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Definition: sched_ule.c:524
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Definition: kern_mutex.c:685
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Definition: sched_ule.c:87
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Definition: subr_param.c:84
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Definition: sched_ule.c:2415
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Definition: sched_ule.c:2548
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Definition: sched_ule.c:1601