freebsd-dev/sys/kern/sched_ule.c

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/*-
* Copyright (c) 2003, Jeffrey Roberson <jeff@freebsd.org>
* All rights reserved.
*
* 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 unmodified, 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 ``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 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.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/vmmeter.h>
#ifdef DDB
#include <ddb/ddb.h>
#endif
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
#include <machine/cpu.h>
/* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
/* XXX This is bogus compatability crap for ps */
static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
static void sched_setup(void *dummy);
SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL)
/*
* These datastructures are allocated within their parent datastructure but
* are scheduler specific.
*/
struct ke_sched {
int ske_slice;
struct runq *ske_runq;
/* The following variables are only used for pctcpu calculation */
int ske_ltick; /* Last tick that we were running on */
int ske_ftick; /* First tick that we were running on */
int ske_ticks; /* Tick count */
};
#define ke_slice ke_sched->ske_slice
#define ke_runq ke_sched->ske_runq
#define ke_ltick ke_sched->ske_ltick
#define ke_ftick ke_sched->ske_ftick
#define ke_ticks ke_sched->ske_ticks
struct kg_sched {
int skg_slptime;
};
#define kg_slptime kg_sched->skg_slptime
struct td_sched {
int std_slptime;
};
#define td_slptime td_sched->std_slptime
struct ke_sched ke_sched;
struct kg_sched kg_sched;
struct td_sched td_sched;
struct ke_sched *kse0_sched = &ke_sched;
struct kg_sched *ksegrp0_sched = &kg_sched;
struct p_sched *proc0_sched = NULL;
struct td_sched *thread0_sched = &td_sched;
/*
* This priority range has 20 priorities on either end that are reachable
* only through nice values.
*/
#define SCHED_PRI_NRESV 40
#define SCHED_PRI_RANGE ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1) - \
SCHED_PRI_NRESV)
/*
* These determine how sleep time effects the priority of a process.
*
* SLP_MAX: Maximum amount of accrued sleep time.
* SLP_SCALE: Scale the number of ticks slept across the dynamic priority
* range.
* SLP_TOPRI: Convert a number of ticks slept into a priority value.
* SLP_DECAY: Reduce the sleep time to 50% for every granted slice.
*/
#define SCHED_SLP_MAX (hz * 2)
#define SCHED_SLP_SCALE(slp) (((slp) * SCHED_PRI_RANGE) / SCHED_SLP_MAX)
#define SCHED_SLP_TOPRI(slp) (SCHED_PRI_RANGE - SCHED_SLP_SCALE((slp)) + \
SCHED_PRI_NRESV / 2)
#define SCHED_SLP_DECAY(slp) ((slp) / 2) /* XXX Multiple kses break */
/*
* These parameters and macros determine the size of the time slice that is
* granted to each thread.
*
* SLICE_MIN: Minimum time slice granted, in units of ticks.
* SLICE_MAX: Maximum time slice granted.
* SLICE_RANGE: Range of available time slices scaled by hz.
* SLICE_SCALE: The number slices granted per unit of pri or slp.
* PRI_TOSLICE: Compute a slice size that is proportional to the priority.
* SLP_TOSLICE: Compute a slice size that is inversely proportional to the
* amount of time slept. (smaller slices for interactive ksegs)
* PRI_COMP: This determines what fraction of the actual slice comes from
* the slice size computed from the priority.
* SLP_COMP: This determines what component of the actual slice comes from
* the slize size computed from the sleep time.
*/
#define SCHED_SLICE_MIN (hz / 100)
#define SCHED_SLICE_MAX (hz / 10)
#define SCHED_SLICE_RANGE (SCHED_SLICE_MAX - SCHED_SLICE_MIN + 1)
#define SCHED_SLICE_SCALE(val, max) (((val) * SCHED_SLICE_RANGE) / (max))
#define SCHED_PRI_TOSLICE(pri) \
(SCHED_SLICE_MAX - SCHED_SLICE_SCALE((pri), SCHED_PRI_RANGE))
#define SCHED_SLP_TOSLICE(slp) \
(SCHED_SLICE_MAX - SCHED_SLICE_SCALE((slp), SCHED_SLP_MAX))
#define SCHED_SLP_COMP(slice) (((slice) / 5) * 3) /* 60% */
#define SCHED_PRI_COMP(slice) (((slice) / 5) * 2) /* 40% */
/*
* This macro determines whether or not the kse belongs on the current or
* next run queue.
*/
#define SCHED_CURR(kg) ((kg)->kg_slptime > (hz / 4) || \
(kg)->kg_pri_class != PRI_TIMESHARE)
/*
* Cpu percentage computation macros and defines.
*
* SCHED_CPU_TIME: Number of seconds to average the cpu usage across.
* SCHED_CPU_TICKS: Number of hz ticks to average the cpu usage across.
*/
#define SCHED_CPU_TIME 60
#define SCHED_CPU_TICKS (hz * SCHED_CPU_TIME)
/*
* kseq - pair of runqs per processor
*/
struct kseq {
struct runq ksq_runqs[2];
struct runq *ksq_curr;
struct runq *ksq_next;
int ksq_load; /* Total runnable */
};
/*
* One kse queue per processor.
*/
struct kseq kseq_cpu[MAXCPU];
static int sched_slice(struct ksegrp *kg);
static int sched_priority(struct ksegrp *kg);
void sched_pctcpu_update(struct kse *ke);
void sched_check_runqs(void);
int sched_pickcpu(void);
static void
sched_setup(void *dummy)
{
int i;
mtx_lock_spin(&sched_lock);
/* init kseqs */
for (i = 0; i < MAXCPU; i++) {
kseq_cpu[i].ksq_load = 0;
kseq_cpu[i].ksq_curr = &kseq_cpu[i].ksq_runqs[0];
kseq_cpu[i].ksq_next = &kseq_cpu[i].ksq_runqs[1];
runq_init(kseq_cpu[i].ksq_curr);
runq_init(kseq_cpu[i].ksq_next);
}
mtx_unlock_spin(&sched_lock);
}
/*
* Scale the scheduling priority according to the "interactivity" of this
* process.
*/
static int
sched_priority(struct ksegrp *kg)
{
int pri;
if (kg->kg_pri_class != PRI_TIMESHARE)
return (kg->kg_user_pri);
pri = SCHED_SLP_TOPRI(kg->kg_slptime);
CTR2(KTR_RUNQ, "sched_priority: slptime: %d\tpri: %d",
kg->kg_slptime, pri);
pri += PRI_MIN_TIMESHARE;
pri += kg->kg_nice;
if (pri > PRI_MAX_TIMESHARE)
pri = PRI_MAX_TIMESHARE;
else if (pri < PRI_MIN_TIMESHARE)
pri = PRI_MIN_TIMESHARE;
kg->kg_user_pri = pri;
return (kg->kg_user_pri);
}
/*
* Calculate a time slice based on the process priority.
*/
static int
sched_slice(struct ksegrp *kg)
{
int pslice;
int sslice;
int slice;
int pri;
pri = kg->kg_user_pri;
pri -= PRI_MIN_TIMESHARE;
pslice = SCHED_PRI_TOSLICE(pri);
sslice = SCHED_SLP_TOSLICE(kg->kg_slptime);
slice = SCHED_SLP_COMP(sslice) + SCHED_PRI_COMP(pslice);
kg->kg_slptime = SCHED_SLP_DECAY(kg->kg_slptime);
CTR4(KTR_RUNQ,
"sched_slice: pri: %d\tsslice: %d\tpslice: %d\tslice: %d",
pri, sslice, pslice, slice);
if (slice < SCHED_SLICE_MIN)
slice = SCHED_SLICE_MIN;
else if (slice > SCHED_SLICE_MAX)
slice = SCHED_SLICE_MAX;
return (slice);
}
int
sched_rr_interval(void)
{
return (SCHED_SLICE_MAX);
}
void
sched_pctcpu_update(struct kse *ke)
{
/*
* Adjust counters and watermark for pctcpu calc.
*/
ke->ke_ticks = (ke->ke_ticks / (ke->ke_ltick - ke->ke_ftick)) *
SCHED_CPU_TICKS;
ke->ke_ltick = ticks;
ke->ke_ftick = ke->ke_ltick - SCHED_CPU_TICKS;
}
#ifdef SMP
int
sched_pickcpu(void)
{
int cpu;
int load;
int i;
if (!smp_started)
return (0);
cpu = PCPU_GET(cpuid);
load = kseq_cpu[cpu].ksq_load;
for (i = 0; i < mp_maxid; i++) {
if (CPU_ABSENT(i))
continue;
if (kseq_cpu[i].ksq_load < load) {
cpu = i;
load = kseq_cpu[i].ksq_load;
}
}
CTR1(KTR_RUNQ, "sched_pickcpu: %d", cpu);
return (cpu);
}
#else
int
sched_pickcpu(void)
{
return (0);
}
#endif
void
sched_prio(struct thread *td, u_char prio)
{
struct kse *ke;
struct runq *rq;
mtx_assert(&sched_lock, MA_OWNED);
ke = td->td_kse;
td->td_priority = prio;
if (TD_ON_RUNQ(td)) {
rq = ke->ke_runq;
runq_remove(rq, ke);
runq_add(rq, ke);
}
}
void
sched_switchout(struct thread *td)
{
struct kse *ke;
mtx_assert(&sched_lock, MA_OWNED);
ke = td->td_kse;
td->td_last_kse = ke;
td->td_lastcpu = ke->ke_oncpu;
ke->ke_flags &= ~KEF_NEEDRESCHED;
if (TD_IS_RUNNING(td)) {
setrunqueue(td);
return;
} else
td->td_kse->ke_runq = NULL;
/*
* We will not be on the run queue. So we must be
* sleeping or similar.
*/
if (td->td_proc->p_flag & P_KSES)
kse_reassign(ke);
}
void
sched_switchin(struct thread *td)
{
/* struct kse *ke = td->td_kse; */
mtx_assert(&sched_lock, MA_OWNED);
td->td_kse->ke_oncpu = PCPU_GET(cpuid); /* XXX */
if (td->td_ksegrp->kg_pri_class == PRI_TIMESHARE &&
td->td_priority != td->td_ksegrp->kg_user_pri)
curthread->td_kse->ke_flags |= KEF_NEEDRESCHED;
}
void
sched_nice(struct ksegrp *kg, int nice)
{
struct thread *td;
kg->kg_nice = nice;
sched_priority(kg);
FOREACH_THREAD_IN_GROUP(kg, td) {
td->td_kse->ke_flags |= KEF_NEEDRESCHED;
}
}
void
sched_sleep(struct thread *td, u_char prio)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_slptime = ticks;
td->td_priority = prio;
/*
* If this is an interactive task clear its queue so it moves back
* on to curr when it wakes up. Otherwise let it stay on the queue
* that it was assigned to.
*/
if (SCHED_CURR(td->td_kse->ke_ksegrp))
td->td_kse->ke_runq = NULL;
}
void
sched_wakeup(struct thread *td)
{
struct ksegrp *kg;
mtx_assert(&sched_lock, MA_OWNED);
/*
* Let the kseg know how long we slept for. This is because process
* interactivity behavior is modeled in the kseg.
*/
kg = td->td_ksegrp;
if (td->td_slptime) {
kg->kg_slptime += ticks - td->td_slptime;
if (kg->kg_slptime > SCHED_SLP_MAX)
kg->kg_slptime = SCHED_SLP_MAX;
td->td_priority = sched_priority(kg);
}
td->td_slptime = 0;
setrunqueue(td);
if (td->td_priority < curthread->td_priority)
curthread->td_kse->ke_flags |= KEF_NEEDRESCHED;
}
/*
* Penalize the parent for creating a new child and initialize the child's
* priority.
*/
void
sched_fork(struct ksegrp *kg, struct ksegrp *child)
{
struct kse *ckse;
struct kse *pkse;
mtx_assert(&sched_lock, MA_OWNED);
ckse = FIRST_KSE_IN_KSEGRP(child);
pkse = FIRST_KSE_IN_KSEGRP(kg);
/* XXX Need something better here */
child->kg_slptime = kg->kg_slptime;
child->kg_user_pri = kg->kg_user_pri;
if (pkse->ke_oncpu != PCPU_GET(cpuid)) {
printf("pkse->ke_oncpu = %d\n", pkse->ke_oncpu);
printf("cpuid = %d", PCPU_GET(cpuid));
Debugger("stop");
}
ckse->ke_slice = pkse->ke_slice;
ckse->ke_oncpu = pkse->ke_oncpu; /* sched_pickcpu(); */
ckse->ke_runq = NULL;
/*
* Claim that we've been running for one second for statistical
* purposes.
*/
ckse->ke_ticks = 0;
ckse->ke_ltick = ticks;
ckse->ke_ftick = ticks - hz;
}
/*
* Return some of the child's priority and interactivity to the parent.
*/
void
sched_exit(struct ksegrp *kg, struct ksegrp *child)
{
struct kseq *kseq;
struct kse *ke;
/* XXX Need something better here */
mtx_assert(&sched_lock, MA_OWNED);
kg->kg_slptime = child->kg_slptime;
sched_priority(kg);
/*
* We drop the load here so that the running process leaves us with a
* load of at least one.
*/
ke = FIRST_KSE_IN_KSEGRP(kg);
kseq = &kseq_cpu[ke->ke_oncpu];
}
int sched_clock_switches;
void
sched_clock(struct thread *td)
{
struct kse *ke;
#if 0
struct kse *nke;
#endif
struct ksegrp *kg;
struct kseq *kseq;
int cpu;
cpu = PCPU_GET(cpuid);
kseq = &kseq_cpu[cpu];
mtx_assert(&sched_lock, MA_OWNED);
KASSERT((td != NULL), ("schedclock: null thread pointer"));
ke = td->td_kse;
kg = td->td_ksegrp;
if (td->td_kse->ke_flags & KEF_IDLEKSE) {
#if 0
if (nke && nke->ke_ksegrp->kg_pri_class == PRI_TIMESHARE) {
printf("Idle running with %s on the runq!\n",
nke->ke_proc->p_comm);
Debugger("stop");
}
#endif
return;
}
#if 0
nke = runq_choose(kseq->ksq_curr);
if (nke && nke->ke_thread &&
nke->ke_thread->td_priority < td->td_priority) {
sched_clock_switches++;
ke->ke_flags |= KEF_NEEDRESCHED;
}
#endif
/*
* We used a tick, decrease our total sleep time. This decreases our
* "interactivity".
*/
if (kg->kg_slptime)
kg->kg_slptime--;
/*
* We used up one time slice.
*/
ke->ke_slice--;
/*
* We're out of time, recompute priorities and requeue
*/
if (ke->ke_slice == 0) {
struct kseq *kseq;
kseq = &kseq_cpu[ke->ke_oncpu];
td->td_priority = sched_priority(kg);
ke->ke_slice = sched_slice(kg);
ke->ke_flags |= KEF_NEEDRESCHED;
ke->ke_runq = NULL;
}
ke->ke_ticks += 10000;
ke->ke_ltick = ticks;
/* Go up to one second beyond our max and then trim back down */
if (ke->ke_ftick + SCHED_CPU_TICKS + hz < ke->ke_ltick)
sched_pctcpu_update(ke);
}
void sched_print_load(void);
void
sched_print_load(void)
{
int cpu;
for (cpu = 0; cpu < mp_maxid; cpu++) {
if (CPU_ABSENT(cpu))
continue;
printf("%d: %d\n", cpu, kseq_cpu[cpu].ksq_load);
}
}
int
sched_runnable(void)
{
struct kseq *kseq;
int cpu;
cpu = PCPU_GET(cpuid);
kseq = &kseq_cpu[cpu];
if (runq_check(kseq->ksq_curr))
return (1);
if (runq_check(kseq->ksq_next))
return (1);
#ifdef SMP
if (smp_started) {
int i;
for (i = 0; i < mp_maxid; i++) {
if (CPU_ABSENT(i))
continue;
if (kseq_cpu[i].ksq_load && i != cpu)
return (1);
}
}
#endif
return (0);
}
void
sched_userret(struct thread *td)
{
struct ksegrp *kg;
kg = td->td_ksegrp;
if (td->td_priority != kg->kg_user_pri) {
mtx_lock_spin(&sched_lock);
td->td_priority = kg->kg_user_pri;
mtx_unlock_spin(&sched_lock);
}
}
void
sched_check_runqs(void)
{
struct kseq *kseq;
int cpu;
for (cpu = 0; cpu < mp_maxid; cpu++) {
if (CPU_ABSENT(cpu))
continue;
kseq = &kseq_cpu[cpu];
if (kseq->ksq_load !=
(runq_depth(kseq->ksq_curr) + runq_depth(kseq->ksq_next))) {
printf("CPU: %d\tload: %d\tcurr: %d\tnext: %d\n",
cpu, kseq->ksq_load, runq_depth(kseq->ksq_curr),
runq_depth(kseq->ksq_next));
Debugger("Imbalance");
}
}
}
struct kse * sched_choose_kseq(struct kseq *kseq);
struct kse *
sched_choose_kseq(struct kseq *kseq)
{
struct kse *ke;
struct runq *swap;
if ((ke = runq_choose(kseq->ksq_curr)) == NULL) {
swap = kseq->ksq_curr;
kseq->ksq_curr = kseq->ksq_next;
kseq->ksq_next = swap;
ke = runq_choose(kseq->ksq_curr);
}
return (ke);
}
struct kse *
sched_choose(void)
{
struct kse *ke;
int cpu;
cpu = PCPU_GET(cpuid);
ke = sched_choose_kseq(&kseq_cpu[cpu]);
if (ke) {
runq_remove(ke->ke_runq, ke);
ke->ke_state = KES_THREAD;
#ifdef SMP
kseq_cpu[cpu].ksq_load--;
#if 0
sched_check_runqs();
#endif
#endif
}
#ifdef SMP
if (ke == NULL && smp_started) {
int load;
int me;
int i;
me = cpu;
/*
* Find the cpu with the highest load and steal one proc.
*/
for (load = 0, i = 0; i < mp_maxid; i++) {
if (CPU_ABSENT(i) || i == me)
continue;
if (kseq_cpu[i].ksq_load > load) {
load = kseq_cpu[i].ksq_load;
cpu = i;
}
}
if (load) {
ke = sched_choose_kseq(&kseq_cpu[cpu]);
kseq_cpu[cpu].ksq_load--;
ke->ke_state = KES_THREAD;
runq_remove(ke->ke_runq, ke);
ke->ke_runq = NULL;
ke->ke_oncpu = me;
}
}
#endif
return (ke);
}
void
sched_add(struct kse *ke)
{
mtx_assert(&sched_lock, MA_OWNED);
KASSERT((ke->ke_thread != NULL), ("runq_add: No thread on KSE"));
KASSERT((ke->ke_thread->td_kse != NULL),
("runq_add: No KSE on thread"));
KASSERT(ke->ke_state != KES_ONRUNQ,
("runq_add: kse %p (%s) already in run queue", ke,
ke->ke_proc->p_comm));
KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
("runq_add: process swapped out"));
if (ke->ke_runq == NULL) {
struct kseq *kseq;
kseq = &kseq_cpu[ke->ke_oncpu];
if (SCHED_CURR(ke->ke_ksegrp))
ke->ke_runq = kseq->ksq_curr;
else
ke->ke_runq = kseq->ksq_next;
}
ke->ke_ksegrp->kg_runq_kses++;
ke->ke_state = KES_ONRUNQ;
runq_add(ke->ke_runq, ke);
#ifdef SMP
kseq_cpu[ke->ke_oncpu].ksq_load++;
#if 0
sched_check_runqs();
#endif
#endif
}
void
sched_rem(struct kse *ke)
{
mtx_assert(&sched_lock, MA_OWNED);
/* KASSERT((ke->ke_state == KES_ONRUNQ), ("KSE not on run queue")); */
runq_remove(ke->ke_runq, ke);
ke->ke_runq = NULL;
ke->ke_state = KES_THREAD;
ke->ke_ksegrp->kg_runq_kses--;
#ifdef SMP
kseq_cpu[ke->ke_oncpu].ksq_load--;
#if 0
sched_check_runqs();
#endif
#endif
}
fixpt_t
sched_pctcpu(struct kse *ke)
{
fixpt_t pctcpu;
pctcpu = 0;
if (ke->ke_ticks) {
int rtick;
/* Update to account for time potentially spent sleeping */
ke->ke_ltick = ticks;
sched_pctcpu_update(ke);
/* How many rtick per second ? */
rtick = ke->ke_ticks / (SCHED_CPU_TIME * 10000);
pctcpu = (FSCALE * ((FSCALE * rtick)/stathz)) >> FSHIFT;
}
ke->ke_proc->p_swtime = ke->ke_ltick - ke->ke_ftick;
return (pctcpu);
}
int
sched_sizeof_kse(void)
{
return (sizeof(struct kse) + sizeof(struct ke_sched));
}
int
sched_sizeof_ksegrp(void)
{
return (sizeof(struct ksegrp) + sizeof(struct kg_sched));
}
int
sched_sizeof_proc(void)
{
return (sizeof(struct proc));
}
int
sched_sizeof_thread(void)
{
return (sizeof(struct thread) + sizeof(struct td_sched));
}