kern_racct.c

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/*-
 * Copyright (c) 2010 The FreeBSD Foundation
 * All rights reserved.
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $BSDSUniX$
 */

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include "opt_kdtrace.h"
#include "opt_sched.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/eventhandler.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/loginclass.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/sbuf.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/smp.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/umtx.h>
#include <machine/smp.h>

#ifdef RCTL
#include <sys/rctl.h>
#endif

#ifdef RACCT

FEATURE(racct, "Resource Accounting");

/*
 * Do not block processes that have their %cpu usage <= pcpu_threshold.
 */
static int pcpu_threshold = 1;

SYSCTL_NODE(_kern, OID_AUTO, racct, CTLFLAG_RW, 0, "Resource Accounting");
SYSCTL_UINT(_kern_racct, OID_AUTO, pcpu_threshold, CTLFLAG_RW, &pcpu_threshold,
    0, "Processes with higher %cpu usage than this value can be throttled.");

/*
 * How many seconds it takes to use the scheduler %cpu calculations.  When a
 * process starts, we compute its %cpu usage by dividing its runtime by the
 * process wall clock time.  After RACCT_PCPU_SECS pass, we use the value
 * provided by the scheduler.
 */
#define RACCT_PCPU_SECS         3

static struct mtx racct_lock;
MTX_SYSINIT(racct_lock, &racct_lock, "racct lock", MTX_DEF);

static uma_zone_t racct_zone;

static void racct_sub_racct(struct racct *dest, const struct racct *src);
static void racct_sub_cred_locked(struct ucred *cred, int resource,
                uint64_t amount);
static void racct_add_cred_locked(struct ucred *cred, int resource,
                uint64_t amount);

SDT_PROVIDER_DEFINE(racct);
SDT_PROBE_DEFINE3(racct, kernel, rusage, add, "struct proc *", "int",
    "uint64_t");
SDT_PROBE_DEFINE3(racct, kernel, rusage, add__failure,
    "struct proc *", "int", "uint64_t");
SDT_PROBE_DEFINE3(racct, kernel, rusage, add__cred, "struct ucred *",
    "int", "uint64_t");
SDT_PROBE_DEFINE3(racct, kernel, rusage, add__force, "struct proc *",
    "int", "uint64_t");
SDT_PROBE_DEFINE3(racct, kernel, rusage, set, "struct proc *", "int",
    "uint64_t");
SDT_PROBE_DEFINE3(racct, kernel, rusage, set__failure,
    "struct proc *", "int", "uint64_t");
SDT_PROBE_DEFINE3(racct, kernel, rusage, sub, "struct proc *", "int",
    "uint64_t");
SDT_PROBE_DEFINE3(racct, kernel, rusage, sub__cred, "struct ucred *",
    "int", "uint64_t");
SDT_PROBE_DEFINE1(racct, kernel, racct, create, "struct racct *");
SDT_PROBE_DEFINE1(racct, kernel, racct, destroy, "struct racct *");
SDT_PROBE_DEFINE2(racct, kernel, racct, join, "struct racct *",
    "struct racct *");
SDT_PROBE_DEFINE2(racct, kernel, racct, join__failure,
    "struct racct *", "struct racct *");
SDT_PROBE_DEFINE2(racct, kernel, racct, leave, "struct racct *",
    "struct racct *");

int racct_types[] = {
        [RACCT_CPU] =
                RACCT_IN_MILLIONS,
        [RACCT_DATA] =
                RACCT_RECLAIMABLE | RACCT_INHERITABLE | RACCT_DENIABLE,
        [RACCT_STACK] =
                RACCT_RECLAIMABLE | RACCT_INHERITABLE | RACCT_DENIABLE,
        [RACCT_CORE] =
                RACCT_DENIABLE,
        [RACCT_RSS] =
                RACCT_RECLAIMABLE,
        [RACCT_MEMLOCK] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE,
        [RACCT_NPROC] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE,
        [RACCT_NOFILE] =
                RACCT_RECLAIMABLE | RACCT_INHERITABLE | RACCT_DENIABLE,
        [RACCT_VMEM] =
                RACCT_RECLAIMABLE | RACCT_INHERITABLE | RACCT_DENIABLE,
        [RACCT_NPTS] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE | RACCT_SLOPPY,
        [RACCT_SWAP] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE | RACCT_SLOPPY,
        [RACCT_NTHR] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE,
        [RACCT_MSGQQUEUED] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE | RACCT_SLOPPY,
        [RACCT_MSGQSIZE] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE | RACCT_SLOPPY,
        [RACCT_NMSGQ] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE | RACCT_SLOPPY,
        [RACCT_NSEM] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE | RACCT_SLOPPY,
        [RACCT_NSEMOP] =
                RACCT_RECLAIMABLE | RACCT_INHERITABLE | RACCT_DENIABLE,
        [RACCT_NSHM] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE | RACCT_SLOPPY,
        [RACCT_SHMSIZE] =
                RACCT_RECLAIMABLE | RACCT_DENIABLE | RACCT_SLOPPY,
        [RACCT_WALLCLOCK] =
                RACCT_IN_MILLIONS,
        [RACCT_PCTCPU] =
                RACCT_DECAYING | RACCT_DENIABLE | RACCT_IN_MILLIONS };

static const fixpt_t RACCT_DECAY_FACTOR = 0.3 * FSCALE;

#ifdef SCHED_4BSD
/*
 * Contains intermediate values for %cpu calculations to avoid using floating
 * point in the kernel.
 * ccpu_exp[k] = FSCALE * (ccpu/FSCALE)^k = FSCALE * exp(-k/20)
 * It is needed only for the 4BSD scheduler, because in ULE, the ccpu equals to
 * zero so the calculations are more straightforward.
 */
fixpt_t ccpu_exp[] = {
        [0] = FSCALE * 1,
        [1] = FSCALE * 0.95122942450071400909,
        [2] = FSCALE * 0.90483741803595957316,
        [3] = FSCALE * 0.86070797642505780722,
        [4] = FSCALE * 0.81873075307798185866,
        [5] = FSCALE * 0.77880078307140486824,
        [6] = FSCALE * 0.74081822068171786606,
        [7] = FSCALE * 0.70468808971871343435,
        [8] = FSCALE * 0.67032004603563930074,
        [9] = FSCALE * 0.63762815162177329314,
        [10] = FSCALE * 0.60653065971263342360,
        [11] = FSCALE * 0.57694981038048669531,
        [12] = FSCALE * 0.54881163609402643262,
        [13] = FSCALE * 0.52204577676101604789,
        [14] = FSCALE * 0.49658530379140951470,
        [15] = FSCALE * 0.47236655274101470713,
        [16] = FSCALE * 0.44932896411722159143,
        [17] = FSCALE * 0.42741493194872666992,
        [18] = FSCALE * 0.40656965974059911188,
        [19] = FSCALE * 0.38674102345450120691,
        [20] = FSCALE * 0.36787944117144232159,
        [21] = FSCALE * 0.34993774911115535467,
        [22] = FSCALE * 0.33287108369807955328,
        [23] = FSCALE * 0.31663676937905321821,
        [24] = FSCALE * 0.30119421191220209664,
        [25] = FSCALE * 0.28650479686019010032,
        [26] = FSCALE * 0.27253179303401260312,
        [27] = FSCALE * 0.25924026064589150757,
        [28] = FSCALE * 0.24659696394160647693,
        [29] = FSCALE * 0.23457028809379765313,
        [30] = FSCALE * 0.22313016014842982893,
        [31] = FSCALE * 0.21224797382674305771,
        [32] = FSCALE * 0.20189651799465540848,
        [33] = FSCALE * 0.19204990862075411423,
        [34] = FSCALE * 0.18268352405273465022,
        [35] = FSCALE * 0.17377394345044512668,
        [36] = FSCALE * 0.16529888822158653829,
        [37] = FSCALE * 0.15723716631362761621,
        [38] = FSCALE * 0.14956861922263505264,
        [39] = FSCALE * 0.14227407158651357185,
        [40] = FSCALE * 0.13533528323661269189,
        [41] = FSCALE * 0.12873490358780421886,
        [42] = FSCALE * 0.12245642825298191021,
        [43] = FSCALE * 0.11648415777349695786,
        [44] = FSCALE * 0.11080315836233388333,
        [45] = FSCALE * 0.10539922456186433678,
        [46] = FSCALE * 0.10025884372280373372,
        [47] = FSCALE * 0.09536916221554961888,
        [48] = FSCALE * 0.09071795328941250337,
        [49] = FSCALE * 0.08629358649937051097,
        [50] = FSCALE * 0.08208499862389879516,
        [51] = FSCALE * 0.07808166600115315231,
        [52] = FSCALE * 0.07427357821433388042,
        [53] = FSCALE * 0.07065121306042958674,
        [54] = FSCALE * 0.06720551273974976512,
        [55] = FSCALE * 0.06392786120670757270,
        [56] = FSCALE * 0.06081006262521796499,
        [57] = FSCALE * 0.05784432087483846296,
        [58] = FSCALE * 0.05502322005640722902,
        [59] = FSCALE * 0.05233970594843239308,
        [60] = FSCALE * 0.04978706836786394297,
        [61] = FSCALE * 0.04735892439114092119,
        [62] = FSCALE * 0.04504920239355780606,
        [63] = FSCALE * 0.04285212686704017991,
        [64] = FSCALE * 0.04076220397836621516,
        [65] = FSCALE * 0.03877420783172200988,
        [66] = FSCALE * 0.03688316740124000544,
        [67] = FSCALE * 0.03508435410084502588,
        [68] = FSCALE * 0.03337326996032607948,
        [69] = FSCALE * 0.03174563637806794323,
        [70] = FSCALE * 0.03019738342231850073,
        [71] = FSCALE * 0.02872463965423942912,
        [72] = FSCALE * 0.02732372244729256080,
        [73] = FSCALE * 0.02599112877875534358,
        [74] = FSCALE * 0.02472352647033939120,
        [75] = FSCALE * 0.02351774585600910823,
        [76] = FSCALE * 0.02237077185616559577,
        [77] = FSCALE * 0.02127973643837716938,
        [78] = FSCALE * 0.02024191144580438847,
        [79] = FSCALE * 0.01925470177538692429,
        [80] = FSCALE * 0.01831563888873418029,
        [81] = FSCALE * 0.01742237463949351138,
        [82] = FSCALE * 0.01657267540176124754,
        [83] = FSCALE * 0.01576441648485449082,
        [84] = FSCALE * 0.01499557682047770621,
        [85] = FSCALE * 0.01426423390899925527,
        [86] = FSCALE * 0.01356855901220093175,
        [87] = FSCALE * 0.01290681258047986886,
        [88] = FSCALE * 0.01227733990306844117,
        [89] = FSCALE * 0.01167856697039544521,
        [90] = FSCALE * 0.01110899653824230649,
        [91] = FSCALE * 0.01056720438385265337,
        [92] = FSCALE * 0.01005183574463358164,
        [93] = FSCALE * 0.00956160193054350793,
        [94] = FSCALE * 0.00909527710169581709,
        [95] = FSCALE * 0.00865169520312063417,
        [96] = FSCALE * 0.00822974704902002884,
        [97] = FSCALE * 0.00782837754922577143,
        [98] = FSCALE * 0.00744658307092434051,
        [99] = FSCALE * 0.00708340892905212004,
        [100] = FSCALE * 0.00673794699908546709,
        [101] = FSCALE * 0.00640933344625638184,
        [102] = FSCALE * 0.00609674656551563610,
        [103] = FSCALE * 0.00579940472684214321,
        [104] = FSCALE * 0.00551656442076077241,
        [105] = FSCALE * 0.00524751839918138427,
        [106] = FSCALE * 0.00499159390691021621,
        [107] = FSCALE * 0.00474815099941147558,
        [108] = FSCALE * 0.00451658094261266798,
        [109] = FSCALE * 0.00429630469075234057,
        [110] = FSCALE * 0.00408677143846406699,
};
#endif

#define CCPU_EXP_MAX    110

/*
 * This function is analogical to the getpcpu() function in the ps(1) command.
 * They should both calculate in the same way so that the racct %cpu
 * calculations are consistent with the values showed by the ps(1) tool.
 * The calculations are more complex in the 4BSD scheduler because of the value
 * of the ccpu variable.  In ULE it is defined to be zero which saves us some
 * work.
 */
static uint64_t
racct_getpcpu(struct proc *p, u_int pcpu)
{
        u_int swtime;
#ifdef SCHED_4BSD
        fixpt_t pctcpu, pctcpu_next;
#endif
#ifdef SMP
        struct pcpu *pc;
        int found;
#endif
        fixpt_t p_pctcpu;
        struct thread *td;

        /*
         * If the process is swapped out, we count its %cpu usage as zero.
         * This behaviour is consistent with the userland ps(1) tool.
         */
        if ((p->p_flag & P_INMEM) == 0)
                return (0);
        swtime = (ticks - p->p_swtick) / hz;

        /*
         * For short-lived processes, the sched_pctcpu() returns small
         * values even for cpu intensive processes.  Therefore we use
         * our own estimate in this case.
         */
        if (swtime < RACCT_PCPU_SECS)
                return (pcpu);

        p_pctcpu = 0;
        FOREACH_THREAD_IN_PROC(p, td) {
                if (td == PCPU_GET(idlethread))
                        continue;
#ifdef SMP
                found = 0;
                STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
                        if (td == pc->pc_idlethread) {
                                found = 1;
                                break;
                        }
                }
                if (found)
                        continue;
#endif
                thread_lock(td);
#ifdef SCHED_4BSD
                pctcpu = sched_pctcpu(td);
                /* Count also the yet unfinished second. */
                pctcpu_next = (pctcpu * ccpu_exp[1]) >> FSHIFT;
                pctcpu_next += sched_pctcpu_delta(td);
                p_pctcpu += max(pctcpu, pctcpu_next);
#else
                /*
                 * In ULE the %cpu statistics are updated on every
                 * sched_pctcpu() call.  So special calculations to
                 * account for the latest (unfinished) second are
                 * not needed.
                 */
                p_pctcpu += sched_pctcpu(td);
#endif
                thread_unlock(td);
        }

#ifdef SCHED_4BSD
        if (swtime <= CCPU_EXP_MAX)
                return ((100 * (uint64_t)p_pctcpu * 1000000) /
                    (FSCALE - ccpu_exp[swtime]));
#endif

        return ((100 * (uint64_t)p_pctcpu * 1000000) / FSCALE);
}

static void
racct_add_racct(struct racct *dest, const struct racct *src)
{
        int i;

        mtx_assert(&racct_lock, MA_OWNED);

        /*
         * Update resource usage in dest.
         */
        for (i = 0; i <= RACCT_MAX; i++) {
                KASSERT(dest->r_resources[i] >= 0,
                    ("%s: resource %d propagation meltdown: dest < 0",
                    __func__, i));
                KASSERT(src->r_resources[i] >= 0,
                    ("%s: resource %d propagation meltdown: src < 0",
                    __func__, i));
                dest->r_resources[i] += src->r_resources[i];
        }
}

static void
racct_sub_racct(struct racct *dest, const struct racct *src)
{
        int i;

        mtx_assert(&racct_lock, MA_OWNED);

        /*
         * Update resource usage in dest.
         */
        for (i = 0; i <= RACCT_MAX; i++) {
                if (!RACCT_IS_SLOPPY(i) && !RACCT_IS_DECAYING(i)) {
                        KASSERT(dest->r_resources[i] >= 0,
                            ("%s: resource %d propagation meltdown: dest < 0",
                            __func__, i));
                        KASSERT(src->r_resources[i] >= 0,
                            ("%s: resource %d propagation meltdown: src < 0",
                            __func__, i));
                        KASSERT(src->r_resources[i] <= dest->r_resources[i],
                            ("%s: resource %d propagation meltdown: src > dest",
                            __func__, i));
                }
                if (RACCT_CAN_DROP(i)) {
                        dest->r_resources[i] -= src->r_resources[i];
                        if (dest->r_resources[i] < 0) {
                                KASSERT(RACCT_IS_SLOPPY(i) ||
                                    RACCT_IS_DECAYING(i),
                                    ("%s: resource %d usage < 0", __func__, i));
                                dest->r_resources[i] = 0;
                        }
                }
        }
}

void
racct_create(struct racct **racctp)
{

        SDT_PROBE1(racct, kernel, racct, create, racctp);

        KASSERT(*racctp == NULL, ("racct already allocated"));

        *racctp = uma_zalloc(racct_zone, M_WAITOK | M_ZERO);
}

static void
racct_destroy_locked(struct racct **racctp)
{
        int i;
        struct racct *racct;

        SDT_PROBE1(racct, kernel, racct, destroy, racctp);

        mtx_assert(&racct_lock, MA_OWNED);
        KASSERT(racctp != NULL, ("NULL racctp"));
        KASSERT(*racctp != NULL, ("NULL racct"));

        racct = *racctp;

        for (i = 0; i <= RACCT_MAX; i++) {
                if (RACCT_IS_SLOPPY(i))
                        continue;
                if (!RACCT_IS_RECLAIMABLE(i))
                        continue;
                KASSERT(racct->r_resources[i] == 0,
                    ("destroying non-empty racct: "
                    "%ju allocated for resource %d\n",
                    racct->r_resources[i], i));
        }
        uma_zfree(racct_zone, racct);
        *racctp = NULL;
}

void
racct_destroy(struct racct **racct)
{

        mtx_lock(&racct_lock);
        racct_destroy_locked(racct);
        mtx_unlock(&racct_lock);
}

/*
 * Increase consumption of 'resource' by 'amount' for 'racct'
 * and all its parents.  Differently from other cases, 'amount' here
 * may be less than zero.
 */
static void
racct_alloc_resource(struct racct *racct, int resource,
    uint64_t amount)
{

        mtx_assert(&racct_lock, MA_OWNED);
        KASSERT(racct != NULL, ("NULL racct"));

        racct->r_resources[resource] += amount;
        if (racct->r_resources[resource] < 0) {
                KASSERT(RACCT_IS_SLOPPY(resource) || RACCT_IS_DECAYING(resource),
                    ("%s: resource %d usage < 0", __func__, resource));
                racct->r_resources[resource] = 0;
        }
        
        /*
         * There are some cases where the racct %cpu resource would grow
         * beyond 100%.
         * For example in racct_proc_exit() we add the process %cpu usage
         * to the ucred racct containers.  If too many processes terminated
         * in a short time span, the ucred %cpu resource could grow too much.
         * Also, the 4BSD scheduler sometimes returns for a thread more than
         * 100% cpu usage.  So we set a boundary here to 100%.
         */
        if ((resource == RACCT_PCTCPU) &&
            (racct->r_resources[RACCT_PCTCPU] > 100 * 1000000))
                racct->r_resources[RACCT_PCTCPU] = 100 * 1000000;
}

static int
racct_add_locked(struct proc *p, int resource, uint64_t amount)
{
#ifdef RCTL
        int error;
#endif

        SDT_PROBE3(racct, kernel, rusage, add, p, resource, amount);

        /*
         * We need proc lock to dereference p->p_ucred.
         */
        PROC_LOCK_ASSERT(p, MA_OWNED);

#ifdef RCTL
        error = rctl_enforce(p, resource, amount);
        if (error && RACCT_IS_DENIABLE(resource)) {
                SDT_PROBE3(racct, kernel, rusage, add__failure, p, resource,
                    amount);
                return (error);
        }
#endif
        racct_alloc_resource(p->p_racct, resource, amount);
        racct_add_cred_locked(p->p_ucred, resource, amount);

        return (0);
}

/*
 * Increase allocation of 'resource' by 'amount' for process 'p'.
 * Return 0 if it's below limits, or errno, if it's not.
 */
int
racct_add(struct proc *p, int resource, uint64_t amount)
{
        int error;

        mtx_lock(&racct_lock);
        error = racct_add_locked(p, resource, amount);
        mtx_unlock(&racct_lock);
        return (error);
}

static void
racct_add_cred_locked(struct ucred *cred, int resource, uint64_t amount)
{
        struct prison *pr;

        SDT_PROBE3(racct, kernel, rusage, add__cred, cred, resource, amount);

        racct_alloc_resource(cred->cr_ruidinfo->ui_racct, resource, amount);
        for (pr = cred->cr_prison; pr != NULL; pr = pr->pr_parent)
                racct_alloc_resource(pr->pr_prison_racct->prr_racct, resource,
                    amount);
        racct_alloc_resource(cred->cr_loginclass->lc_racct, resource, amount);
}

/*
 * Increase allocation of 'resource' by 'amount' for credential 'cred'.
 * Doesn't check for limits and never fails.
 *
 * XXX: Shouldn't this ever return an error?
 */
void
racct_add_cred(struct ucred *cred, int resource, uint64_t amount)
{

        mtx_lock(&racct_lock);
        racct_add_cred_locked(cred, resource, amount);
        mtx_unlock(&racct_lock);
}

/*
 * Increase allocation of 'resource' by 'amount' for process 'p'.
 * Doesn't check for limits and never fails.
 */
void
racct_add_force(struct proc *p, int resource, uint64_t amount)
{

        SDT_PROBE3(racct, kernel, rusage, add__force, p, resource, amount);

        /*
         * We need proc lock to dereference p->p_ucred.
         */
        PROC_LOCK_ASSERT(p, MA_OWNED);

        mtx_lock(&racct_lock);
        racct_alloc_resource(p->p_racct, resource, amount);
        mtx_unlock(&racct_lock);
        racct_add_cred(p->p_ucred, resource, amount);
}

static int
racct_set_locked(struct proc *p, int resource, uint64_t amount)
{
        int64_t old_amount, decayed_amount;
        int64_t diff_proc, diff_cred;
#ifdef RCTL
        int error;
#endif

        SDT_PROBE3(racct, kernel, rusage, set, p, resource, amount);

        /*
         * We need proc lock to dereference p->p_ucred.
         */
        PROC_LOCK_ASSERT(p, MA_OWNED);

        old_amount = p->p_racct->r_resources[resource];
        /*
         * The diffs may be negative.
         */
        diff_proc = amount - old_amount;
        if (RACCT_IS_DECAYING(resource)) {
                /*
                 * Resources in per-credential racct containers may decay.
                 * If this is the case, we need to calculate the difference
                 * between the new amount and the proportional value of the
                 * old amount that has decayed in the ucred racct containers.
                 */
                decayed_amount = old_amount * RACCT_DECAY_FACTOR / FSCALE;
                diff_cred = amount - decayed_amount;
        } else
                diff_cred = diff_proc;
#ifdef notyet
        KASSERT(diff_proc >= 0 || RACCT_CAN_DROP(resource),
            ("%s: usage of non-droppable resource %d dropping", __func__,
             resource));
#endif
#ifdef RCTL
        if (diff_proc > 0) {
                error = rctl_enforce(p, resource, diff_proc);
                if (error && RACCT_IS_DENIABLE(resource)) {
                        SDT_PROBE3(racct, kernel, rusage, set__failure, p,
                            resource, amount);
                        return (error);
                }
        }
#endif
        racct_alloc_resource(p->p_racct, resource, diff_proc);
        if (diff_cred > 0)
                racct_add_cred_locked(p->p_ucred, resource, diff_cred);
        else if (diff_cred < 0)
                racct_sub_cred_locked(p->p_ucred, resource, -diff_cred);

        return (0);
}

/*
 * Set allocation of 'resource' to 'amount' for process 'p'.
 * Return 0 if it's below limits, or errno, if it's not.
 *
 * Note that decreasing the allocation always returns 0,
 * even if it's above the limit.
 */
int
racct_set(struct proc *p, int resource, uint64_t amount)
{
        int error;

        mtx_lock(&racct_lock);
        error = racct_set_locked(p, resource, amount);
        mtx_unlock(&racct_lock);
        return (error);
}

static void
racct_set_force_locked(struct proc *p, int resource, uint64_t amount)
{
        int64_t old_amount, decayed_amount;
        int64_t diff_proc, diff_cred;

        SDT_PROBE3(racct, kernel, rusage, set, p, resource, amount);

        /*
         * We need proc lock to dereference p->p_ucred.
         */
        PROC_LOCK_ASSERT(p, MA_OWNED);

        old_amount = p->p_racct->r_resources[resource];
        /*
         * The diffs may be negative.
         */
        diff_proc = amount - old_amount;
        if (RACCT_IS_DECAYING(resource)) {
                /*
                 * Resources in per-credential racct containers may decay.
                 * If this is the case, we need to calculate the difference
                 * between the new amount and the proportional value of the
                 * old amount that has decayed in the ucred racct containers.
                 */
                decayed_amount = old_amount * RACCT_DECAY_FACTOR / FSCALE;
                diff_cred = amount - decayed_amount;
        } else
                diff_cred = diff_proc;

        racct_alloc_resource(p->p_racct, resource, diff_proc);
        if (diff_cred > 0)
                racct_add_cred_locked(p->p_ucred, resource, diff_cred);
        else if (diff_cred < 0)
                racct_sub_cred_locked(p->p_ucred, resource, -diff_cred);
}

void
racct_set_force(struct proc *p, int resource, uint64_t amount)
{
        mtx_lock(&racct_lock);
        racct_set_force_locked(p, resource, amount);
        mtx_unlock(&racct_lock);
}

/*
 * Returns amount of 'resource' the process 'p' can keep allocated.
 * Allocating more than that would be denied, unless the resource
 * is marked undeniable.  Amount of already allocated resource does
 * not matter.
 */
uint64_t
racct_get_limit(struct proc *p, int resource)
{

#ifdef RCTL
        return (rctl_get_limit(p, resource));
#else
        return (UINT64_MAX);
#endif
}

/*
 * Returns amount of 'resource' the process 'p' can keep allocated.
 * Allocating more than that would be denied, unless the resource
 * is marked undeniable.  Amount of already allocated resource does
 * matter.
 */
uint64_t
racct_get_available(struct proc *p, int resource)
{

#ifdef RCTL
        return (rctl_get_available(p, resource));
#else
        return (UINT64_MAX);
#endif
}

/*
 * Returns amount of the %cpu resource that process 'p' can add to its %cpu
 * utilization.  Adding more than that would lead to the process being
 * throttled.
 */
static int64_t
racct_pcpu_available(struct proc *p)
{

#ifdef RCTL
        return (rctl_pcpu_available(p));
#else
        return (INT64_MAX);
#endif
}

/*
 * Decrease allocation of 'resource' by 'amount' for process 'p'.
 */
void
racct_sub(struct proc *p, int resource, uint64_t amount)
{

        SDT_PROBE3(racct, kernel, rusage, sub, p, resource, amount);

        /*
         * We need proc lock to dereference p->p_ucred.
         */
        PROC_LOCK_ASSERT(p, MA_OWNED);
        KASSERT(RACCT_CAN_DROP(resource),
            ("%s: called for non-droppable resource %d", __func__, resource));

        mtx_lock(&racct_lock);
        KASSERT(amount <= p->p_racct->r_resources[resource],
            ("%s: freeing %ju of resource %d, which is more "
             "than allocated %jd for %s (pid %d)", __func__, amount, resource,
            (intmax_t)p->p_racct->r_resources[resource], p->p_comm, p->p_pid));

        racct_alloc_resource(p->p_racct, resource, -amount);
        racct_sub_cred_locked(p->p_ucred, resource, amount);
        mtx_unlock(&racct_lock);
}

static void
racct_sub_cred_locked(struct ucred *cred, int resource, uint64_t amount)
{
        struct prison *pr;

        SDT_PROBE3(racct, kernel, rusage, sub__cred, cred, resource, amount);

#ifdef notyet
        KASSERT(RACCT_CAN_DROP(resource),
            ("%s: called for resource %d which can not drop", __func__,
             resource));
#endif

        racct_alloc_resource(cred->cr_ruidinfo->ui_racct, resource, -amount);
        for (pr = cred->cr_prison; pr != NULL; pr = pr->pr_parent)
                racct_alloc_resource(pr->pr_prison_racct->prr_racct, resource,
                    -amount);
        racct_alloc_resource(cred->cr_loginclass->lc_racct, resource, -amount);
}

/*
 * Decrease allocation of 'resource' by 'amount' for credential 'cred'.
 */
void
racct_sub_cred(struct ucred *cred, int resource, uint64_t amount)
{

        mtx_lock(&racct_lock);
        racct_sub_cred_locked(cred, resource, amount);
        mtx_unlock(&racct_lock);
}

/*
 * Inherit resource usage information from the parent process.
 */
int
racct_proc_fork(struct proc *parent, struct proc *child)
{
        int i, error = 0;

        /*
         * Create racct for the child process.
         */
        racct_create(&child->p_racct);

        PROC_LOCK(parent);
        PROC_LOCK(child);
        mtx_lock(&racct_lock);

#ifdef RCTL
        error = rctl_proc_fork(parent, child);
        if (error != 0)
                goto out;
#endif

        /* Init process cpu time. */
        child->p_prev_runtime = 0;
        child->p_throttled = 0;

        /*
         * Inherit resource usage.
         */
        for (i = 0; i <= RACCT_MAX; i++) {
                if (parent->p_racct->r_resources[i] == 0 ||
                    !RACCT_IS_INHERITABLE(i))
                        continue;

                error = racct_set_locked(child, i,
                    parent->p_racct->r_resources[i]);
                if (error != 0)
                        goto out;
        }

        error = racct_add_locked(child, RACCT_NPROC, 1);
        error += racct_add_locked(child, RACCT_NTHR, 1);

out:
        mtx_unlock(&racct_lock);
        PROC_UNLOCK(child);
        PROC_UNLOCK(parent);

        if (error != 0)
                racct_proc_exit(child);

        return (error);
}

/*
 * Called at the end of fork1(), to handle rules that require the process
 * to be fully initialized.
 */
void
racct_proc_fork_done(struct proc *child)
{

#ifdef RCTL
        PROC_LOCK(child);
        mtx_lock(&racct_lock);
        rctl_enforce(child, RACCT_NPROC, 0);
        rctl_enforce(child, RACCT_NTHR, 0);
        mtx_unlock(&racct_lock);
        PROC_UNLOCK(child);
#endif
}

void
racct_proc_exit(struct proc *p)
{
        int i;
        uint64_t runtime;
        struct timeval wallclock;
        uint64_t pct_estimate, pct;

        PROC_LOCK(p);
        /*
         * We don't need to calculate rux, proc_reap() has already done this.
         */
        runtime = cputick2usec(p->p_rux.rux_runtime);
#ifdef notyet
        KASSERT(runtime >= p->p_prev_runtime, ("runtime < p_prev_runtime"));
#else
        if (runtime < p->p_prev_runtime)
                runtime = p->p_prev_runtime;
#endif
        microuptime(&wallclock);
        timevalsub(&wallclock, &p->p_stats->p_start);
        if (wallclock.tv_sec > 0 || wallclock.tv_usec > 0) {
                pct_estimate = (1000000 * runtime * 100) /
                    ((uint64_t)wallclock.tv_sec * 1000000 +
                    wallclock.tv_usec);
        } else
                pct_estimate = 0;
        pct = racct_getpcpu(p, pct_estimate);

        mtx_lock(&racct_lock);
        racct_set_locked(p, RACCT_CPU, runtime);
        racct_add_cred_locked(p->p_ucred, RACCT_PCTCPU, pct);

        for (i = 0; i <= RACCT_MAX; i++) {
                if (p->p_racct->r_resources[i] == 0)
                        continue;
                if (!RACCT_IS_RECLAIMABLE(i))
                        continue;
                racct_set_locked(p, i, 0);
        }

        mtx_unlock(&racct_lock);
        PROC_UNLOCK(p);

#ifdef RCTL
        rctl_racct_release(p->p_racct);
#endif
        racct_destroy(&p->p_racct);
}

/*
 * Called after credentials change, to move resource utilisation
 * between raccts.
 */
void
racct_proc_ucred_changed(struct proc *p, struct ucred *oldcred,
    struct ucred *newcred)
{
        struct uidinfo *olduip, *newuip;
        struct loginclass *oldlc, *newlc;
        struct prison *oldpr, *newpr, *pr;

        PROC_LOCK_ASSERT(p, MA_NOTOWNED);

        newuip = newcred->cr_ruidinfo;
        olduip = oldcred->cr_ruidinfo;
        newlc = newcred->cr_loginclass;
        oldlc = oldcred->cr_loginclass;
        newpr = newcred->cr_prison;
        oldpr = oldcred->cr_prison;

        mtx_lock(&racct_lock);
        if (newuip != olduip) {
                racct_sub_racct(olduip->ui_racct, p->p_racct);
                racct_add_racct(newuip->ui_racct, p->p_racct);
        }
        if (newlc != oldlc) {
                racct_sub_racct(oldlc->lc_racct, p->p_racct);
                racct_add_racct(newlc->lc_racct, p->p_racct);
        }
        if (newpr != oldpr) {
                for (pr = oldpr; pr != NULL; pr = pr->pr_parent)
                        racct_sub_racct(pr->pr_prison_racct->prr_racct,
                            p->p_racct);
                for (pr = newpr; pr != NULL; pr = pr->pr_parent)
                        racct_add_racct(pr->pr_prison_racct->prr_racct,
                            p->p_racct);
        }
        mtx_unlock(&racct_lock);

#ifdef RCTL
        rctl_proc_ucred_changed(p, newcred);
#endif
}

void
racct_move(struct racct *dest, struct racct *src)
{

        mtx_lock(&racct_lock);

        racct_add_racct(dest, src);
        racct_sub_racct(src, src);

        mtx_unlock(&racct_lock);
}

static void
racct_proc_throttle(struct proc *p)
{
        struct thread *td;
#ifdef SMP
        int cpuid;
#endif

        PROC_LOCK_ASSERT(p, MA_OWNED);

        /*
         * Do not block kernel processes.  Also do not block processes with
         * low %cpu utilization to improve interactivity.
         */
        if (((p->p_flag & (P_SYSTEM | P_KTHREAD)) != 0) ||
            (p->p_racct->r_resources[RACCT_PCTCPU] <= pcpu_threshold))
                return;
        p->p_throttled = 1;

        FOREACH_THREAD_IN_PROC(p, td) {
                thread_lock(td);
                switch (td->td_state) {
                case TDS_RUNQ:
                        /*
                         * If the thread is on the scheduler run-queue, we can
                         * not just remove it from there.  So we set the flag
                         * TDF_NEEDRESCHED for the thread, so that once it is
                         * running, it is taken off the cpu as soon as possible.
                         */
                        td->td_flags |= TDF_NEEDRESCHED;
                        break;
                case TDS_RUNNING:
                        /*
                         * If the thread is running, we request a context
                         * switch for it by setting the TDF_NEEDRESCHED flag.
                         */
                        td->td_flags |= TDF_NEEDRESCHED;
#ifdef SMP
                        cpuid = td->td_oncpu;
                        if ((cpuid != NOCPU) && (td != curthread))
                                ipi_cpu(cpuid, IPI_AST);
#endif
                        break;
                default:
                        break;
                }
                thread_unlock(td);
        }
}

static void
racct_proc_wakeup(struct proc *p)
{
        PROC_LOCK_ASSERT(p, MA_OWNED);

        if (p->p_throttled) {
                p->p_throttled = 0;
                wakeup(p->p_racct);
        }
}

static void
racct_decay_resource(struct racct *racct, void * res, void* dummy)
{
        int resource;
        int64_t r_old, r_new;

        resource = *(int *)res;
        r_old = racct->r_resources[resource];

        /* If there is nothing to decay, just exit. */
        if (r_old <= 0)
                return;

        mtx_lock(&racct_lock);
        r_new = r_old * RACCT_DECAY_FACTOR / FSCALE;
        racct->r_resources[resource] = r_new;
        mtx_unlock(&racct_lock);
}

static void
racct_decay(int resource)
{
        ui_racct_foreach(racct_decay_resource, &resource, NULL);
        loginclass_racct_foreach(racct_decay_resource, &resource, NULL);
        prison_racct_foreach(racct_decay_resource, &resource, NULL);
}

static void
racctd(void)
{
        struct thread *td;
        struct proc *p;
        struct timeval wallclock;
        uint64_t runtime;
        uint64_t pct, pct_estimate;

        for (;;) {
                racct_decay(RACCT_PCTCPU);

                sx_slock(&allproc_lock);

                LIST_FOREACH(p, &zombproc, p_list) {
                        PROC_LOCK(p);
                        racct_set(p, RACCT_PCTCPU, 0);
                        PROC_UNLOCK(p);
                }

                FOREACH_PROC_IN_SYSTEM(p) {
                        PROC_LOCK(p);
                        if (p->p_state != PRS_NORMAL) {
                                PROC_UNLOCK(p);
                                continue;
                        }

                        microuptime(&wallclock);
                        timevalsub(&wallclock, &p->p_stats->p_start);
                        PROC_SLOCK(p);
                        FOREACH_THREAD_IN_PROC(p, td)
                                ruxagg(p, td);
                        runtime = cputick2usec(p->p_rux.rux_runtime);
                        PROC_SUNLOCK(p);
#ifdef notyet
                        KASSERT(runtime >= p->p_prev_runtime,
                            ("runtime < p_prev_runtime"));
#else
                        if (runtime < p->p_prev_runtime)
                                runtime = p->p_prev_runtime;
#endif
                        p->p_prev_runtime = runtime;
                        if (wallclock.tv_sec > 0 || wallclock.tv_usec > 0) {
                                pct_estimate = (1000000 * runtime * 100) /
                                    ((uint64_t)wallclock.tv_sec * 1000000 +
                                    wallclock.tv_usec);
                        } else
                                pct_estimate = 0;
                        pct = racct_getpcpu(p, pct_estimate);
                        mtx_lock(&racct_lock);
                        racct_set_force_locked(p, RACCT_PCTCPU, pct);
                        racct_set_locked(p, RACCT_CPU, runtime);
                        racct_set_locked(p, RACCT_WALLCLOCK,
                            (uint64_t)wallclock.tv_sec * 1000000 +
                            wallclock.tv_usec);
                        mtx_unlock(&racct_lock);
                        PROC_UNLOCK(p);
                }

                /*
                 * To ensure that processes are throttled in a fair way, we need
                 * to iterate over all processes again and check the limits
                 * for %cpu resource only after ucred racct containers have been
                 * properly filled.
                 */
                FOREACH_PROC_IN_SYSTEM(p) {
                        PROC_LOCK(p);
                        if (p->p_state != PRS_NORMAL) {
                                PROC_UNLOCK(p);
                                continue;
                        }

                        if (racct_pcpu_available(p) <= 0)
                                racct_proc_throttle(p);
                        else if (p->p_throttled)
                                racct_proc_wakeup(p);
                        PROC_UNLOCK(p);
                }
                sx_sunlock(&allproc_lock);
                pause("-", hz);
        }
}

static struct kproc_desc racctd_kp = {
        "racctd",
        racctd,
        NULL
};
SYSINIT(racctd, SI_SUB_RACCTD, SI_ORDER_FIRST, kproc_start, &racctd_kp);

static void
racct_init(void)
{

        racct_zone = uma_zcreate("racct", sizeof(struct racct),
            NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
        /*
         * XXX: Move this somewhere.
         */
        prison0.pr_prison_racct = prison_racct_find("0");
}
SYSINIT(racct, SI_SUB_RACCT, SI_ORDER_FIRST, racct_init, NULL);

#else /* !RACCT */

int
racct_add(struct proc *p, int resource, uint64_t amount)
{

        return (0);
}

void
racct_add_cred(struct ucred *cred, int resource, uint64_t amount)
{
}

void
racct_add_force(struct proc *p, int resource, uint64_t amount)
{

        return;
}

int
racct_set(struct proc *p, int resource, uint64_t amount)
{

        return (0);
}

void
racct_set_force(struct proc *p, int resource, uint64_t amount)
{
}

void
racct_sub(struct proc *p, int resource, uint64_t amount)
{
}

void
racct_sub_cred(struct ucred *cred, int resource, uint64_t amount)
{
}

uint64_t
racct_get_limit(struct proc *p, int resource)
{

        return (UINT64_MAX);
}

uint64_t
racct_get_available(struct proc *p, int resource)
{

        return (UINT64_MAX);
}

void
racct_create(struct racct **racctp)
{
}

void
racct_destroy(struct racct **racctp)
{
}

int
racct_proc_fork(struct proc *parent, struct proc *child)
{

        return (0);
}

void
racct_proc_fork_done(struct proc *child)
{
}

void
racct_proc_exit(struct proc *p)
{
}

#endif /* !RACCT */