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freebsd-dev/sys/kern/sched_ule.c
Jeff Roberson 112b6d3aa9 - Remove kseq_find(), we no longer scan other cpu's run queues when we go 
idle.  They figure out that we're idle fast enough that the cache pollution
   introduces by scanning their run queue is more expensive than waiting
   a little longer.
 - Add kseq_setidle() to mark us as being idle.  Use this in place of
   kseq_find().
 - Remove kseq_load_highest(), kseq_find() was the only consumer of this
   interface.  kseq_balance() has it's own customized version that finds the
   lowest and highest loads simultaneously.

Continuously told that this would be faster by:	terry
2003-11-03 03:27:22 +00:00

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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/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. */
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)
#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 && class != PRI_ITHD &&
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);
}
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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