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freebsd-skq/sys/kern/sched_ule.c

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/*-
* Copyright (c) 2002-2003, 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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/resource.h>
#include <sys/resourcevar.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>
#include <machine/smp.h>
#define KTR_ULE KTR_NFS
/* 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)
static SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "SCHED");
static int sched_strict;
SYSCTL_INT(_kern_sched, OID_AUTO, strict, CTLFLAG_RD, &sched_strict, 0, "");
static int slice_min = 1;
SYSCTL_INT(_kern_sched, OID_AUTO, slice_min, CTLFLAG_RW, &slice_min, 0, "");
static int slice_max = 10;
SYSCTL_INT(_kern_sched, OID_AUTO, slice_max, CTLFLAG_RW, &slice_max, 0, "");
int realstathz;
int tickincr = 1;
#ifdef SMP
/* Callout to handle load balancing SMP systems. */
static struct callout kseq_lb_callout;
#endif
/*
* 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 */
/* CPU that we have affinity for. */
u_char ske_cpu;
};
#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
#define ke_cpu ke_sched->ske_cpu
#define ke_assign ke_procq.tqe_next
#define KEF_ASSIGNED KEF_SCHED0 /* KSE is being migrated. */
#define KEF_PINNED KEF_SCHED1 /* KSE is temporarily bound. */
#define KEF_BOUND KEF_SCHED2 /* KSE can not migrate. */
struct kg_sched {
int skg_slptime; /* Number of ticks we vol. slept */
int skg_runtime; /* Number of ticks we were running */
};
#define kg_slptime kg_sched->skg_slptime
#define kg_runtime kg_sched->skg_runtime
struct td_sched {
int std_slptime;
};
#define td_slptime td_sched->std_slptime
struct td_sched td_sched;
struct ke_sched ke_sched;
struct kg_sched kg_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;
/*
* The priority is primarily determined by the interactivity score. Thus, we
* give lower(better) priorities to kse groups that use less CPU. The nice
* value is then directly added to this to allow nice to have some effect
* on latency.
*
* PRI_RANGE: Total priority range for timeshare threads.
* PRI_NRESV: Number of nice values.
* PRI_BASE: The start of the dynamic range.
*/
#define SCHED_PRI_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1)
#define SCHED_PRI_NRESV ((PRIO_MAX - PRIO_MIN) + 1)
#define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
#define SCHED_PRI_BASE (PRI_MIN_TIMESHARE)
#define SCHED_PRI_INTERACT(score) \
((score) * SCHED_PRI_RANGE / SCHED_INTERACT_MAX)
/*
* These determine the interactivity of a process.
*
* SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate
* before throttling back.
* SLP_RUN_FORK: Maximum slp+run time to inherit at fork time.
* INTERACT_MAX: Maximum interactivity value. Smaller is better.
* INTERACT_THRESH: Threshhold for placement on the current runq.
*/
#define SCHED_SLP_RUN_MAX ((hz * 5) << 10)
#define SCHED_SLP_RUN_FORK ((hz / 2) << 10)
#define SCHED_INTERACT_MAX (100)
#define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
#define SCHED_INTERACT_THRESH (30)
/*
* 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 val in the range of [0, max].
* SLICE_NICE: Determine the amount of slice granted to a scaled nice.
* SLICE_NTHRESH: The nice cutoff point for slice assignment.
*/
#define SCHED_SLICE_MIN (slice_min)
#define SCHED_SLICE_MAX (slice_max)
#define SCHED_SLICE_NTHRESH (SCHED_PRI_NHALF - 1)
#define SCHED_SLICE_RANGE (SCHED_SLICE_MAX - SCHED_SLICE_MIN + 1)
#define SCHED_SLICE_SCALE(val, max) (((val) * SCHED_SLICE_RANGE) / (max))
#define SCHED_SLICE_NICE(nice) \
(SCHED_SLICE_MAX - SCHED_SLICE_SCALE((nice), SCHED_SLICE_NTHRESH))
/*
* This macro determines whether or not the kse belongs on the current or
* next run queue.
*/
#define SCHED_INTERACTIVE(kg) \
(sched_interact_score(kg) < SCHED_INTERACT_THRESH)
#define SCHED_CURR(kg, ke) \
(ke->ke_thread->td_priority != kg->kg_user_pri || \
SCHED_INTERACTIVE(kg))
/*
* 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 10
#define SCHED_CPU_TICKS (hz * SCHED_CPU_TIME)
/*
* kseq - per processor runqs and statistics.
*/
#define KSEQ_NCLASS (PRI_IDLE + 1) /* Number of run classes. */
struct kseq {
struct runq ksq_idle; /* Queue of IDLE threads. */
struct runq ksq_timeshare[2]; /* Run queues for !IDLE. */
struct runq *ksq_next; /* Next timeshare queue. */
struct runq *ksq_curr; /* Current queue. */
int ksq_load_timeshare; /* Load for timeshare. */
int ksq_load; /* Aggregate load. */
short ksq_nice[SCHED_PRI_NRESV]; /* KSEs in each nice bin. */
short ksq_nicemin; /* Least nice. */
#ifdef SMP
int ksq_load_transferable; /* kses that may be migrated. */
int ksq_idled;
unsigned int ksq_rslices; /* Slices on run queue */
int ksq_cpus; /* Count of CPUs in this kseq. */
struct kse *ksq_assigned; /* KSEs assigned by another CPU. */
#endif
};
/*
* One kse queue per processor.
*/
#ifdef SMP
static int kseq_idle;
static struct kseq kseq_cpu[MAXCPU];
static struct kseq *kseq_idmap[MAXCPU];
#define KSEQ_SELF() (kseq_idmap[PCPU_GET(cpuid)])
#define KSEQ_CPU(x) (kseq_idmap[(x)])
#else
static struct kseq kseq_cpu;
#define KSEQ_SELF() (&kseq_cpu)
#define KSEQ_CPU(x) (&kseq_cpu)
#endif
static void sched_slice(struct kse *ke);
static void sched_priority(struct ksegrp *kg);
static int sched_interact_score(struct ksegrp *kg);
static void sched_interact_update(struct ksegrp *kg);
static void sched_interact_fork(struct ksegrp *kg);
static void sched_pctcpu_update(struct kse *ke);
/* Operations on per processor queues */
static struct kse * kseq_choose(struct kseq *kseq);
static void kseq_setup(struct kseq *kseq);
static void kseq_add(struct kseq *kseq, struct kse *ke);
static void kseq_rem(struct kseq *kseq, struct kse *ke);
static void kseq_nice_add(struct kseq *kseq, int nice);
static void kseq_nice_rem(struct kseq *kseq, int nice);
void kseq_print(int cpu);
#ifdef SMP
#if 0
static int sched_pickcpu(void);
#endif
static struct kse *runq_steal(struct runq *rq);
static void kseq_balance(void *arg);
static void kseq_move(struct kseq *from, int cpu);
static __inline void kseq_setidle(struct kseq *kseq);
static void kseq_notify(struct kse *ke, int cpu);
static void kseq_assign(struct kseq *);
static struct kse *kseq_steal(struct kseq *kseq);
#define KSE_CAN_MIGRATE(ke, class) \
((class) != PRI_ITHD && ((ke)->ke_flags & (KEF_BOUND|KEF_PINNED)) == 0)
#endif
void
kseq_print(int cpu)
{
struct kseq *kseq;
int i;
kseq = KSEQ_CPU(cpu);
printf("kseq:\n");
printf("\tload: %d\n", kseq->ksq_load);
printf("\tload REALTIME: %d\n", kseq->ksq_load_timeshare);
#ifdef SMP
printf("\tload transferable: %d\n", kseq->ksq_load_transferable);
#endif
printf("\tnicemin:\t%d\n", kseq->ksq_nicemin);
printf("\tnice counts:\n");
for (i = 0; i < SCHED_PRI_NRESV; i++)
if (kseq->ksq_nice[i])
printf("\t\t%d = %d\n",
i - SCHED_PRI_NHALF, kseq->ksq_nice[i]);
}
static void
kseq_add(struct kseq *kseq, struct kse *ke)
{
int class;
mtx_assert(&sched_lock, MA_OWNED);
class = PRI_BASE(ke->ke_ksegrp->kg_pri_class);
if (class == PRI_TIMESHARE)
kseq->ksq_load_timeshare++;
#ifdef SMP
if (KSE_CAN_MIGRATE(ke, class))
kseq->ksq_load_transferable++;
kseq->ksq_rslices += ke->ke_slice;
#endif
kseq->ksq_load++;
if (ke->ke_ksegrp->kg_pri_class == PRI_TIMESHARE)
CTR6(KTR_ULE, "Add kse %p to %p (slice: %d, pri: %d, nice: %d(%d))",
ke, ke->ke_runq, ke->ke_slice, ke->ke_thread->td_priority,
ke->ke_ksegrp->kg_nice, kseq->ksq_nicemin);
if (ke->ke_ksegrp->kg_pri_class == PRI_TIMESHARE)
kseq_nice_add(kseq, ke->ke_ksegrp->kg_nice);
}
static void
kseq_rem(struct kseq *kseq, struct kse *ke)
{
int class;
mtx_assert(&sched_lock, MA_OWNED);
class = PRI_BASE(ke->ke_ksegrp->kg_pri_class);
if (class == PRI_TIMESHARE)
kseq->ksq_load_timeshare--;
#ifdef SMP
if (KSE_CAN_MIGRATE(ke, class))
kseq->ksq_load_transferable--;
kseq->ksq_rslices -= ke->ke_slice;
#endif
kseq->ksq_load--;
ke->ke_runq = NULL;
if (ke->ke_ksegrp->kg_pri_class == PRI_TIMESHARE)
kseq_nice_rem(kseq, ke->ke_ksegrp->kg_nice);
}
static void
kseq_nice_add(struct kseq *kseq, int nice)
{
mtx_assert(&sched_lock, MA_OWNED);
/* Normalize to zero. */
kseq->ksq_nice[nice + SCHED_PRI_NHALF]++;
if (nice < kseq->ksq_nicemin || kseq->ksq_load_timeshare == 1)
kseq->ksq_nicemin = nice;
}
static void
kseq_nice_rem(struct kseq *kseq, int nice)
{
int n;
mtx_assert(&sched_lock, MA_OWNED);
/* Normalize to zero. */
n = nice + SCHED_PRI_NHALF;
kseq->ksq_nice[n]--;
KASSERT(kseq->ksq_nice[n] >= 0, ("Negative nice count."));
/*
* If this wasn't the smallest nice value or there are more in
* this bucket we can just return. Otherwise we have to recalculate
* the smallest nice.
*/
if (nice != kseq->ksq_nicemin ||
kseq->ksq_nice[n] != 0 ||
kseq->ksq_load_timeshare == 0)
return;
for (; n < SCHED_PRI_NRESV; n++)
if (kseq->ksq_nice[n]) {
kseq->ksq_nicemin = n - SCHED_PRI_NHALF;
return;
}
}
#ifdef SMP
/*
* kseq_balance is a simple CPU load balancing algorithm. It operates by
* finding the least loaded and most loaded cpu and equalizing their load
* by migrating some processes.
*
* Dealing only with two CPUs at a time has two advantages. Firstly, most
* installations will only have 2 cpus. Secondly, load balancing too much at
* once can have an unpleasant effect on the system. The scheduler rarely has
* enough information to make perfect decisions. So this algorithm chooses
* algorithm simplicity and more gradual effects on load in larger systems.
*
* It could be improved by considering the priorities and slices assigned to
* each task prior to balancing them. There are many pathological cases with
* any approach and so the semi random algorithm below may work as well as any.
*
*/
static void
kseq_balance(void *arg)
{
struct kseq *kseq;
int high_load;
int low_load;
int high_cpu;
int low_cpu;
int move;
int diff;
int i;
high_cpu = 0;
low_cpu = 0;
high_load = 0;
low_load = -1;
mtx_lock_spin(&sched_lock);
if (smp_started == 0)
goto out;
for (i = 0; i < mp_maxid; i++) {
if (CPU_ABSENT(i) || (i & stopped_cpus) != 0)
continue;
kseq = KSEQ_CPU(i);
if (kseq->ksq_load > high_load) {
high_load = kseq->ksq_load;
high_cpu = i;
}
if (low_load == -1 || kseq->ksq_load < low_load) {
low_load = kseq->ksq_load;
low_cpu = i;
}
}
kseq = KSEQ_CPU(high_cpu);
high_load = kseq->ksq_load_transferable;
/*
* Nothing to do.
*/
if (high_load < kseq->ksq_cpus + 1)
goto out;
high_load -= kseq->ksq_cpus;
if (low_load >= high_load)
goto out;
diff = high_load - low_load;
move = diff / 2;
if (diff & 0x1)
move++;
for (i = 0; i < move; i++)
kseq_move(kseq, low_cpu);
out:
mtx_unlock_spin(&sched_lock);
callout_reset(&kseq_lb_callout, hz, kseq_balance, NULL);
return;
}
static void
kseq_move(struct kseq *from, int cpu)
{
struct kse *ke;
ke = kseq_steal(from);
runq_remove(ke->ke_runq, ke);
ke->ke_state = KES_THREAD;
kseq_rem(from, ke);
ke->ke_cpu = cpu;
kseq_notify(ke, cpu);
}
static __inline void
kseq_setidle(struct kseq *kseq)
{
if (kseq->ksq_idled)
return;
kseq->ksq_idled = 1;
atomic_set_int(&kseq_idle, PCPU_GET(cpumask));
return;
}
static void
kseq_assign(struct kseq *kseq)
{
struct kse *nke;
struct kse *ke;
do {
ke = kseq->ksq_assigned;
} while(!atomic_cmpset_ptr(&kseq->ksq_assigned, ke, NULL));
for (; ke != NULL; ke = nke) {
nke = ke->ke_assign;
ke->ke_flags &= ~KEF_ASSIGNED;
sched_add(ke->ke_thread);
}
}
static void
kseq_notify(struct kse *ke, int cpu)
{
struct kseq *kseq;
struct thread *td;
struct pcpu *pcpu;
ke->ke_flags |= KEF_ASSIGNED;
kseq = KSEQ_CPU(cpu);
/*
* Place a KSE on another cpu's queue and force a resched.
*/
do {
ke->ke_assign = kseq->ksq_assigned;
} while(!atomic_cmpset_ptr(&kseq->ksq_assigned, ke->ke_assign, ke));
pcpu = pcpu_find(cpu);
td = pcpu->pc_curthread;
if (ke->ke_thread->td_priority < td->td_priority ||
td == pcpu->pc_idlethread) {
td->td_flags |= TDF_NEEDRESCHED;
ipi_selected(1 << cpu, IPI_AST);
}
}
static struct kse *
runq_steal(struct runq *rq)
{
struct rqhead *rqh;
struct rqbits *rqb;
struct kse *ke;
int word;
int bit;
mtx_assert(&sched_lock, MA_OWNED);
rqb = &rq->rq_status;
for (word = 0; word < RQB_LEN; word++) {
if (rqb->rqb_bits[word] == 0)
continue;
for (bit = 0; bit < RQB_BPW; bit++) {
if ((rqb->rqb_bits[word] & (1 << bit)) == 0)
continue;
rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
TAILQ_FOREACH(ke, rqh, ke_procq) {
if (KSE_CAN_MIGRATE(ke,
PRI_BASE(ke->ke_ksegrp->kg_pri_class)))
return (ke);
}
}
}
return (NULL);
}
static struct kse *
kseq_steal(struct kseq *kseq)
{
struct kse *ke;
if ((ke = runq_steal(kseq->ksq_curr)) != NULL)
return (ke);
if ((ke = runq_steal(kseq->ksq_next)) != NULL)
return (ke);
return (runq_steal(&kseq->ksq_idle));
}
#endif /* SMP */
/*
* Pick the highest priority task we have and return it.
*/
static struct kse *
kseq_choose(struct kseq *kseq)
{
struct kse *ke;
struct runq *swap;
mtx_assert(&sched_lock, MA_OWNED);
swap = NULL;
for (;;) {
ke = runq_choose(kseq->ksq_curr);
if (ke == NULL) {
/*
* We already swaped once and didn't get anywhere.
*/
if (swap)
break;
swap = kseq->ksq_curr;
kseq->ksq_curr = kseq->ksq_next;
kseq->ksq_next = swap;
continue;
}
/*
* If we encounter a slice of 0 the kse is in a
* TIMESHARE kse group and its nice was too far out
* of the range that receives slices.
*/
if (ke->ke_slice == 0) {
runq_remove(ke->ke_runq, ke);
sched_slice(ke);
ke->ke_runq = kseq->ksq_next;
runq_add(ke->ke_runq, ke);
continue;
}
return (ke);
}
return (runq_choose(&kseq->ksq_idle));
}
static void
kseq_setup(struct kseq *kseq)
{
runq_init(&kseq->ksq_timeshare[0]);
runq_init(&kseq->ksq_timeshare[1]);
runq_init(&kseq->ksq_idle);
kseq->ksq_curr = &kseq->ksq_timeshare[0];
kseq->ksq_next = &kseq->ksq_timeshare[1];
kseq->ksq_load = 0;
kseq->ksq_load_timeshare = 0;
#ifdef SMP
kseq->ksq_load_transferable = 0;
kseq->ksq_rslices = 0;
kseq->ksq_idled = 0;
kseq->ksq_assigned = NULL;
#endif
}
static void
sched_setup(void *dummy)
{
#ifdef SMP
int i;
#endif
slice_min = (hz/100); /* 10ms */
slice_max = (hz/7); /* ~140ms */
#ifdef SMP
/* init kseqs */
/* Create the idmap. */
#ifdef ULE_HTT_EXPERIMENTAL
if (smp_topology == NULL) {
#else
if (1) {
#endif
for (i = 0; i < MAXCPU; i++) {
kseq_setup(&kseq_cpu[i]);
kseq_idmap[i] = &kseq_cpu[i];
kseq_cpu[i].ksq_cpus = 1;
}
} else {
int j;
for (i = 0; i < smp_topology->ct_count; i++) {
struct cpu_group *cg;
cg = &smp_topology->ct_group[i];
kseq_setup(&kseq_cpu[i]);
for (j = 0; j < MAXCPU; j++)
if ((cg->cg_mask & (1 << j)) != 0)
kseq_idmap[j] = &kseq_cpu[i];
kseq_cpu[i].ksq_cpus = cg->cg_count;
}
}
callout_init(&kseq_lb_callout, CALLOUT_MPSAFE);
kseq_balance(NULL);
#else
kseq_setup(KSEQ_SELF());
#endif
mtx_lock_spin(&sched_lock);
kseq_add(KSEQ_SELF(), &kse0);
mtx_unlock_spin(&sched_lock);
}
/*
* Scale the scheduling priority according to the "interactivity" of this
* process.
*/
static void
sched_priority(struct ksegrp *kg)
{
int pri;
if (kg->kg_pri_class != PRI_TIMESHARE)
return;
pri = SCHED_PRI_INTERACT(sched_interact_score(kg));
pri += SCHED_PRI_BASE;
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;
}
/*
* Calculate a time slice based on the properties of the kseg and the runq
* that we're on. This is only for PRI_TIMESHARE ksegrps.
*/
static void
sched_slice(struct kse *ke)
{
struct kseq *kseq;
struct ksegrp *kg;
kg = ke->ke_ksegrp;
kseq = KSEQ_CPU(ke->ke_cpu);
/*
* Rationale:
* KSEs in interactive ksegs get the minimum slice so that we
* quickly notice if it abuses its advantage.
*
* KSEs in non-interactive ksegs are assigned a slice that is
* based on the ksegs nice value relative to the least nice kseg
* on the run queue for this cpu.
*
* If the KSE is less nice than all others it gets the maximum
* slice and other KSEs will adjust their slice relative to
* this when they first expire.
*
* There is 20 point window that starts relative to the least
* nice kse on the run queue. Slice size is determined by
* the kse distance from the last nice ksegrp.
*
* If the kse is outside of the window it will get no slice
* and will be reevaluated each time it is selected on the
* run queue. The exception to this is nice 0 ksegs when
* a nice -20 is running. They are always granted a minimum
* slice.
*/
if (!SCHED_INTERACTIVE(kg)) {
int nice;
nice = kg->kg_nice + (0 - kseq->ksq_nicemin);
if (kseq->ksq_load_timeshare == 0 ||
kg->kg_nice < kseq->ksq_nicemin)
ke->ke_slice = SCHED_SLICE_MAX;
else if (nice <= SCHED_SLICE_NTHRESH)
ke->ke_slice = SCHED_SLICE_NICE(nice);
else if (kg->kg_nice == 0)
ke->ke_slice = SCHED_SLICE_MIN;
else
ke->ke_slice = 0;
} else
ke->ke_slice = SCHED_SLICE_MIN;
CTR6(KTR_ULE,
"Sliced %p(%d) (nice: %d, nicemin: %d, load: %d, interactive: %d)",
ke, ke->ke_slice, kg->kg_nice, kseq->ksq_nicemin,
kseq->ksq_load_timeshare, SCHED_INTERACTIVE(kg));
return;
}
/*
* This routine enforces a maximum limit on the amount of scheduling history
* kept. It is called after either the slptime or runtime is adjusted.
* This routine will not operate correctly when slp or run times have been
* adjusted to more than double their maximum.
*/
static void
sched_interact_update(struct ksegrp *kg)
{
int sum;
sum = kg->kg_runtime + kg->kg_slptime;
if (sum < SCHED_SLP_RUN_MAX)
return;
/*
* If we have exceeded by more than 1/5th then the algorithm below
* will not bring us back into range. Dividing by two here forces
* us into the range of [3/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
*/
if (sum > (SCHED_INTERACT_MAX / 5) * 6) {
kg->kg_runtime /= 2;
kg->kg_slptime /= 2;
return;
}
kg->kg_runtime = (kg->kg_runtime / 5) * 4;
kg->kg_slptime = (kg->kg_slptime / 5) * 4;
}
static void
sched_interact_fork(struct ksegrp *kg)
{
int ratio;
int sum;
sum = kg->kg_runtime + kg->kg_slptime;
if (sum > SCHED_SLP_RUN_FORK) {
ratio = sum / SCHED_SLP_RUN_FORK;
kg->kg_runtime /= ratio;
kg->kg_slptime /= ratio;
}
}
static int
sched_interact_score(struct ksegrp *kg)
{
int div;
if (kg->kg_runtime > kg->kg_slptime) {
div = max(1, kg->kg_runtime / SCHED_INTERACT_HALF);
return (SCHED_INTERACT_HALF +
(SCHED_INTERACT_HALF - (kg->kg_slptime / div)));
} if (kg->kg_slptime > kg->kg_runtime) {
div = max(1, kg->kg_slptime / SCHED_INTERACT_HALF);
return (kg->kg_runtime / div);
}
/*
* This can happen if slptime and runtime are 0.
*/
return (0);
}
/*
* This is only somewhat accurate since given many processes of the same
* priority they will switch when their slices run out, which will be
* at most SCHED_SLICE_MAX.
*/
int
sched_rr_interval(void)
{
return (SCHED_SLICE_MAX);
}
static void
sched_pctcpu_update(struct kse *ke)
{
/*
* Adjust counters and watermark for pctcpu calc.
*/
if (ke->ke_ltick > ticks - SCHED_CPU_TICKS) {
/*
* Shift the tick count out so that the divide doesn't
* round away our results.
*/
ke->ke_ticks <<= 10;
ke->ke_ticks = (ke->ke_ticks / (ticks - ke->ke_ftick)) *
SCHED_CPU_TICKS;
ke->ke_ticks >>= 10;
} else
ke->ke_ticks = 0;
ke->ke_ltick = ticks;
ke->ke_ftick = ke->ke_ltick - SCHED_CPU_TICKS;
}
#if 0
/* XXX Should be changed to kseq_load_lowest() */
int
sched_pickcpu(void)
{
struct kseq *kseq;
int load;
int cpu;
int i;
mtx_assert(&sched_lock, MA_OWNED);
if (!smp_started)
return (0);
load = 0;
cpu = 0;
for (i = 0; i < mp_maxid; i++) {
if (CPU_ABSENT(i) || (i & stopped_cpus) != 0)
continue;
kseq = KSEQ_CPU(i);
if (kseq->ksq_load < load) {
cpu = i;
load = kseq->ksq_load;
}
}
CTR1(KTR_ULE, "sched_pickcpu: %d", cpu);
return (cpu);
}
#endif
void
sched_prio(struct thread *td, u_char prio)
{
struct kse *ke;
ke = td->td_kse;
mtx_assert(&sched_lock, MA_OWNED);
if (TD_ON_RUNQ(td)) {
/*
* If the priority has been elevated due to priority
* propagation, we may have to move ourselves to a new
* queue. We still call adjustrunqueue below in case kse
* needs to fix things up.
*/
if (prio < td->td_priority && ke &&
(ke->ke_flags & KEF_ASSIGNED) == 0 &&
ke->ke_runq != KSEQ_CPU(ke->ke_cpu)->ksq_curr) {
runq_remove(ke->ke_runq, ke);
ke->ke_runq = KSEQ_CPU(ke->ke_cpu)->ksq_curr;
runq_add(ke->ke_runq, ke);
}
adjustrunqueue(td, prio);
} else
td->td_priority = prio;
}
void
sched_switch(struct thread *td)
{
struct thread *newtd;
struct kse *ke;
mtx_assert(&sched_lock, MA_OWNED);
ke = td->td_kse;
td->td_last_kse = ke;
td->td_lastcpu = td->td_oncpu;
td->td_oncpu = NOCPU;
td->td_flags &= ~TDF_NEEDRESCHED;
if (TD_IS_RUNNING(td)) {
if (td->td_proc->p_flag & P_SA) {
kseq_rem(KSEQ_CPU(ke->ke_cpu), ke);
setrunqueue(td);
} else {
/*
* This queue is always correct except for idle threads
* which have a higher priority due to priority
* propagation.
*/
if (ke->ke_ksegrp->kg_pri_class == PRI_IDLE) {
if (td->td_priority < PRI_MIN_IDLE)
ke->ke_runq = KSEQ_SELF()->ksq_curr;
else
ke->ke_runq = &KSEQ_SELF()->ksq_idle;
}
runq_add(ke->ke_runq, ke);
/* setrunqueue(td); */
}
} else {
if (ke->ke_runq)
kseq_rem(KSEQ_CPU(ke->ke_cpu), ke);
/*
* We will not be on the run queue. So we must be
* sleeping or similar.
*/
if (td->td_proc->p_flag & P_SA)
kse_reassign(ke);
}
newtd = choosethread();
if (td != newtd)
cpu_switch(td, newtd);
sched_lock.mtx_lock = (uintptr_t)td;
td->td_oncpu = PCPU_GET(cpuid);
}
void
sched_nice(struct ksegrp *kg, int nice)
{
struct kse *ke;
struct thread *td;
struct kseq *kseq;
PROC_LOCK_ASSERT(kg->kg_proc, MA_OWNED);
mtx_assert(&sched_lock, MA_OWNED);
/*
* We need to adjust the nice counts for running KSEs.
*/
if (kg->kg_pri_class == PRI_TIMESHARE)
FOREACH_KSE_IN_GROUP(kg, ke) {
if (ke->ke_runq == NULL)
continue;
kseq = KSEQ_CPU(ke->ke_cpu);
kseq_nice_rem(kseq, kg->kg_nice);
kseq_nice_add(kseq, nice);
}
kg->kg_nice = nice;
sched_priority(kg);
FOREACH_THREAD_IN_GROUP(kg, td)
td->td_flags |= TDF_NEEDRESCHED;
}
void
sched_sleep(struct thread *td, u_char prio)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_slptime = ticks;
td->td_priority = prio;
CTR2(KTR_ULE, "sleep kse %p (tick: %d)",
td->td_kse, td->td_slptime);
}
void
sched_wakeup(struct thread *td)
{
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.
*/
if (td->td_slptime) {
struct ksegrp *kg;
int hzticks;
kg = td->td_ksegrp;
hzticks = (ticks - td->td_slptime) << 10;
if (hzticks >= SCHED_SLP_RUN_MAX) {
kg->kg_slptime = SCHED_SLP_RUN_MAX;
kg->kg_runtime = 1;
} else {
kg->kg_slptime += hzticks;
sched_interact_update(kg);
}
sched_priority(kg);
if (td->td_kse)
sched_slice(td->td_kse);
CTR2(KTR_ULE, "wakeup kse %p (%d ticks)",
td->td_kse, hzticks);
td->td_slptime = 0;
}
setrunqueue(td);
}
/*
* Penalize the parent for creating a new child and initialize the child's
* priority.
*/
void
sched_fork(struct proc *p, struct proc *p1)
{
mtx_assert(&sched_lock, MA_OWNED);
sched_fork_ksegrp(FIRST_KSEGRP_IN_PROC(p), FIRST_KSEGRP_IN_PROC(p1));
sched_fork_kse(FIRST_KSE_IN_PROC(p), FIRST_KSE_IN_PROC(p1));
sched_fork_thread(FIRST_THREAD_IN_PROC(p), FIRST_THREAD_IN_PROC(p1));
}
void
sched_fork_kse(struct kse *ke, struct kse *child)
{
child->ke_slice = 1; /* Attempt to quickly learn interactivity. */
child->ke_cpu = ke->ke_cpu; /* sched_pickcpu(); */
child->ke_runq = NULL;
/* Grab our parents cpu estimation information. */
child->ke_ticks = ke->ke_ticks;
child->ke_ltick = ke->ke_ltick;
child->ke_ftick = ke->ke_ftick;
}
void
sched_fork_ksegrp(struct ksegrp *kg, struct ksegrp *child)
{
PROC_LOCK_ASSERT(child->kg_proc, MA_OWNED);
child->kg_slptime = kg->kg_slptime;
child->kg_runtime = kg->kg_runtime;
child->kg_user_pri = kg->kg_user_pri;
child->kg_nice = kg->kg_nice;
sched_interact_fork(child);
kg->kg_runtime += tickincr << 10;
sched_interact_update(kg);
CTR6(KTR_ULE, "sched_fork_ksegrp: %d(%d, %d) - %d(%d, %d)",
kg->kg_proc->p_pid, kg->kg_slptime, kg->kg_runtime,
child->kg_proc->p_pid, child->kg_slptime, child->kg_runtime);
}
void
sched_fork_thread(struct thread *td, struct thread *child)
{
}
void
sched_class(struct ksegrp *kg, int class)
{
struct kseq *kseq;
struct kse *ke;
int nclass;
int oclass;
mtx_assert(&sched_lock, MA_OWNED);
if (kg->kg_pri_class == class)
return;
nclass = PRI_BASE(class);
oclass = PRI_BASE(kg->kg_pri_class);
FOREACH_KSE_IN_GROUP(kg, ke) {
if (ke->ke_state != KES_ONRUNQ &&
ke->ke_state != KES_THREAD)
continue;
kseq = KSEQ_CPU(ke->ke_cpu);
#ifdef SMP
if (KSE_CAN_MIGRATE(ke, oclass))
kseq->ksq_load_transferable--;
if (KSE_CAN_MIGRATE(ke, nclass))
kseq->ksq_load_transferable++;
#endif
if (oclass == PRI_TIMESHARE)
kseq->ksq_load_timeshare--;
if (nclass == PRI_TIMESHARE)
kseq->ksq_load_timeshare++;
if (kg->kg_pri_class == PRI_TIMESHARE)
kseq_nice_rem(kseq, kg->kg_nice);
else if (class == PRI_TIMESHARE)
kseq_nice_add(kseq, kg->kg_nice);
}
kg->kg_pri_class = class;
}
/*
* Return some of the child's priority and interactivity to the parent.
*/
void
sched_exit(struct proc *p, struct proc *child)
{
mtx_assert(&sched_lock, MA_OWNED);
sched_exit_kse(FIRST_KSE_IN_PROC(p), FIRST_KSE_IN_PROC(child));
sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), FIRST_KSEGRP_IN_PROC(child));
}
void
sched_exit_kse(struct kse *ke, struct kse *child)
{
kseq_rem(KSEQ_CPU(child->ke_cpu), child);
}
void
sched_exit_ksegrp(struct ksegrp *kg, struct ksegrp *child)
{
/* kg->kg_slptime += child->kg_slptime; */
kg->kg_runtime += child->kg_runtime;
sched_interact_update(kg);
}
void
sched_exit_thread(struct thread *td, struct thread *child)
{
}
void
sched_clock(struct thread *td)
{
struct kseq *kseq;
struct ksegrp *kg;
struct kse *ke;
/*
* sched_setup() apparently happens prior to stathz being set. We
* need to resolve the timers earlier in the boot so we can avoid
* calculating this here.
*/
if (realstathz == 0) {
realstathz = stathz ? stathz : hz;
tickincr = hz / realstathz;
/*
* XXX This does not work for values of stathz that are much
* larger than hz.
*/
if (tickincr == 0)
tickincr = 1;
}
ke = td->td_kse;
kg = ke->ke_ksegrp;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT((td != NULL), ("schedclock: null thread pointer"));
/* Adjust ticks for pctcpu */
ke->ke_ticks++;
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);
if (td->td_flags & TDF_IDLETD)
return;
CTR4(KTR_ULE, "Tick kse %p (slice: %d, slptime: %d, runtime: %d)",
ke, ke->ke_slice, kg->kg_slptime >> 10, kg->kg_runtime >> 10);
/*
* We only do slicing code for TIMESHARE ksegrps.
*/
if (kg->kg_pri_class != PRI_TIMESHARE)
return;
/*
* We used a tick charge it to the ksegrp so that we can compute our
* interactivity.
*/
kg->kg_runtime += tickincr << 10;
sched_interact_update(kg);
/*
* We used up one time slice.
*/
ke->ke_slice--;
kseq = KSEQ_SELF();
#ifdef SMP
kseq->ksq_rslices--;
#endif
if (ke->ke_slice > 0)
return;
/*
* We're out of time, recompute priorities and requeue.
*/
kseq_rem(kseq, ke);
sched_priority(kg);
sched_slice(ke);
if (SCHED_CURR(kg, ke))
ke->ke_runq = kseq->ksq_curr;
else
ke->ke_runq = kseq->ksq_next;
kseq_add(kseq, ke);
td->td_flags |= TDF_NEEDRESCHED;
}
int
sched_runnable(void)
{
struct kseq *kseq;
int load;
load = 1;
mtx_lock_spin(&sched_lock);
kseq = KSEQ_SELF();
#ifdef SMP
if (kseq->ksq_assigned)
kseq_assign(kseq);
#endif
if ((curthread->td_flags & TDF_IDLETD) != 0) {
if (kseq->ksq_load > 0)
goto out;
} else
if (kseq->ksq_load - 1 > 0)
goto out;
load = 0;
out:
mtx_unlock_spin(&sched_lock);
return (load);
}
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);
}
}
struct kse *
sched_choose(void)
{
struct kseq *kseq;
struct kse *ke;
mtx_assert(&sched_lock, MA_OWNED);
kseq = KSEQ_SELF();
#ifdef SMP
if (kseq->ksq_assigned)
kseq_assign(kseq);
#endif
ke = kseq_choose(kseq);
if (ke) {
#ifdef SMP
if (ke->ke_ksegrp->kg_pri_class == PRI_IDLE)
kseq_setidle(kseq);
#endif
runq_remove(ke->ke_runq, ke);
ke->ke_state = KES_THREAD;
if (ke->ke_ksegrp->kg_pri_class == PRI_TIMESHARE) {
CTR4(KTR_ULE, "Run kse %p from %p (slice: %d, pri: %d)",
ke, ke->ke_runq, ke->ke_slice,
ke->ke_thread->td_priority);
}
return (ke);
}
#ifdef SMP
kseq_setidle(kseq);
#endif
return (NULL);
}
void
sched_add(struct thread *td)
{
struct kseq *kseq;
struct ksegrp *kg;
struct kse *ke;
int class;
mtx_assert(&sched_lock, MA_OWNED);
ke = td->td_kse;
kg = td->td_ksegrp;
if (ke->ke_flags & KEF_ASSIGNED)
return;
kseq = KSEQ_SELF();
KASSERT((ke->ke_thread != NULL), ("sched_add: No thread on KSE"));
KASSERT((ke->ke_thread->td_kse != NULL),
("sched_add: No KSE on thread"));
KASSERT(ke->ke_state != KES_ONRUNQ,
("sched_add: kse %p (%s) already in run queue", ke,
ke->ke_proc->p_comm));
KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
("sched_add: process swapped out"));
KASSERT(ke->ke_runq == NULL,
("sched_add: KSE %p is still assigned to a run queue", ke));
class = PRI_BASE(kg->kg_pri_class);
switch (class) {
case PRI_ITHD:
case PRI_REALTIME:
ke->ke_runq = kseq->ksq_curr;
ke->ke_slice = SCHED_SLICE_MAX;
ke->ke_cpu = PCPU_GET(cpuid);
break;
case PRI_TIMESHARE:
#ifdef SMP
if (ke->ke_cpu != PCPU_GET(cpuid)) {
kseq_notify(ke, ke->ke_cpu);
return;
}
#endif
if (SCHED_CURR(kg, ke))
ke->ke_runq = kseq->ksq_curr;
else
ke->ke_runq = kseq->ksq_next;
break;
case PRI_IDLE:
#ifdef SMP
if (ke->ke_cpu != PCPU_GET(cpuid)) {
kseq_notify(ke, ke->ke_cpu);
return;
}
#endif
/*
* This is for priority prop.
*/
if (ke->ke_thread->td_priority < PRI_MIN_IDLE)
ke->ke_runq = kseq->ksq_curr;
else
ke->ke_runq = &kseq->ksq_idle;
ke->ke_slice = SCHED_SLICE_MIN;
break;
default:
panic("Unknown pri class.");
break;
}
#ifdef SMP
/*
* If there are any idle processors, give them our extra load.
*/
if (kseq_idle && KSE_CAN_MIGRATE(ke, class) &&
kseq->ksq_load_transferable >= kseq->ksq_cpus) {
int cpu;
/*
* Multiple cpus could find this bit simultaneously but the
* race shouldn't be terrible.
*/
cpu = ffs(kseq_idle);
if (cpu) {
cpu--;
atomic_clear_int(&kseq_idle, 1 << cpu);
ke->ke_cpu = cpu;
ke->ke_runq = NULL;
kseq_notify(ke, cpu);
return;
}
}
if (kseq->ksq_idled &&
(class == PRI_TIMESHARE || class == PRI_REALTIME)) {
atomic_clear_int(&kseq_idle, PCPU_GET(cpumask));
kseq->ksq_idled = 0;
}
#endif
if (td->td_priority < curthread->td_priority)
curthread->td_flags |= TDF_NEEDRESCHED;
ke->ke_ksegrp->kg_runq_kses++;
ke->ke_state = KES_ONRUNQ;
runq_add(ke->ke_runq, ke);
kseq_add(kseq, ke);
}
void
sched_rem(struct thread *td)
{
struct kseq *kseq;
struct kse *ke;
ke = td->td_kse;
/*
* It is safe to just return here because sched_rem() is only ever
* used in places where we're immediately going to add the
* kse back on again. In that case it'll be added with the correct
* thread and priority when the caller drops the sched_lock.
*/
if (ke->ke_flags & KEF_ASSIGNED)
return;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT((ke->ke_state == KES_ONRUNQ), ("KSE not on run queue"));
ke->ke_state = KES_THREAD;
ke->ke_ksegrp->kg_runq_kses--;
kseq = KSEQ_CPU(ke->ke_cpu);
runq_remove(ke->ke_runq, ke);
kseq_rem(kseq, ke);
}
fixpt_t
sched_pctcpu(struct thread *td)
{
fixpt_t pctcpu;
struct kse *ke;
pctcpu = 0;
ke = td->td_kse;
if (ke == NULL)
return (0);
mtx_lock_spin(&sched_lock);
if (ke->ke_ticks) {
int rtick;
/*
* Don't update more frequently than twice a second. Allowing
* this causes the cpu usage to decay away too quickly due to
* rounding errors.
*/
if (ke->ke_ltick < (ticks - (hz / 2)))
sched_pctcpu_update(ke);
/* How many rtick per second ? */
rtick = min(ke->ke_ticks / SCHED_CPU_TIME, SCHED_CPU_TICKS);
pctcpu = (FSCALE * ((FSCALE * rtick)/realstathz)) >> FSHIFT;
}
ke->ke_proc->p_swtime = ke->ke_ltick - ke->ke_ftick;
mtx_unlock_spin(&sched_lock);
return (pctcpu);
}
void
sched_pin(struct thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_kse->ke_flags |= KEF_PINNED;
}
void
sched_unpin(struct thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_kse->ke_flags &= ~KEF_PINNED;
}
void
sched_bind(struct thread *td, int cpu)
{
struct kse *ke;
mtx_assert(&sched_lock, MA_OWNED);
ke = td->td_kse;
#ifndef SMP
ke->ke_flags |= KEF_BOUND;
#else
if (PCPU_GET(cpuid) == cpu) {
ke->ke_flags |= KEF_BOUND;
return;
}
/* sched_rem without the runq_remove */
ke->ke_state = KES_THREAD;
ke->ke_ksegrp->kg_runq_kses--;
kseq_rem(KSEQ_CPU(ke->ke_cpu), ke);
ke->ke_cpu = cpu;
kseq_notify(ke, cpu);
/* When we return from mi_switch we'll be on the correct cpu. */
td->td_proc->p_stats->p_ru.ru_nvcsw++;
mi_switch();
#endif
}
void
sched_unbind(struct thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_kse->ke_flags &= ~KEF_BOUND;
}
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));
}
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