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0f54f48225
freebsd/sys/kern/sched_ule.c
Jeff Roberson 2454aaf51c - Use a new flag, KEF_XFERABLE, to record with certainty that this kse had 
contributed to the transferable load count.  This prevents any potential
   problems with sched_pin() being used around calls to setrunqueue().
 - Change the sched_add() load balancing algorithm to try to migrate on
   wakeup.  This attempts to place threads that communicate with each other
   on the same CPU.
 - Don't clear the idle counts in kseq_transfer(), let the cpus do that when
   they call sched_add() from kseq_assign().
 - Correct a few out of date comments.
 - Make sure the ke_cpu field is correct when we preempt.
 - Call kseq_assign() from sched_clock() to catch any assignments that were
   done without IPI.  Presently all assignments are done with an IPI, but I'm
   trying a patch that limits that.
 - Don't migrate a thread if it is still runnable in sched_add().  Previously,
   this could only happen for KSE threads, but due to changes to
   sched_switch() all threads went through this path.
 - Remove some code that was added with preemption but is not necessary.
2004-08-10 07:52:21 +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/kdb.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 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, "Scheduler");
SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ule", 0,
"Scheduler name");
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;
/*
* 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_BOUND KEF_SCHED1 /* KSE can not migrate. */
#define KEF_XFERABLE KEF_SCHED2 /* KSE was added as transferable. */
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_INTERACTIVE (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.
*/
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_transferable;
LIST_ENTRY(kseq) ksq_siblings; /* Next in kseq group. */
struct kseq_group *ksq_group; /* Our processor group. */
volatile struct kse *ksq_assigned; /* assigned by another CPU. */
#else
int ksq_sysload; /* For loadavg, !ITHD load. */
#endif
};
#ifdef SMP
/*
* kseq groups are groups of processors which can cheaply share threads. When
* one processor in the group goes idle it will check the runqs of the other
* processors in its group prior to halting and waiting for an interrupt.
* These groups are suitable for SMT (Symetric Multi-Threading) and not NUMA.
* In a numa environment we'd want an idle bitmap per group and a two tiered
* load balancer.
*/
struct kseq_group {
int ksg_cpus; /* Count of CPUs in this kseq group. */
cpumask_t ksg_cpumask; /* Mask of cpus in this group. */
cpumask_t ksg_idlemask; /* Idle cpus in this group. */
cpumask_t ksg_mask; /* Bit mask for first cpu. */
int ksg_load; /* Total load of this group. */
int ksg_transferable; /* Transferable load of this group. */
LIST_HEAD(, kseq) ksg_members; /* Linked list of all members. */
};
#endif
/*
* One kse queue per processor.
*/
#ifdef SMP
static cpumask_t kseq_idle;
static int ksg_maxid;
static struct kseq kseq_cpu[MAXCPU];
static struct kseq_group kseq_groups[MAXCPU];
static int bal_tick;
static int gbal_tick;
#define KSEQ_SELF() (&kseq_cpu[PCPU_GET(cpuid)])
#define KSEQ_CPU(x) (&kseq_cpu[(x)])
#define KSEQ_ID(x) ((x) - kseq_cpu)
#define KSEQ_GROUP(x) (&kseq_groups[(x)])
#else /* !SMP */
static struct kseq kseq_cpu;
#define KSEQ_SELF() (&kseq_cpu)
#define KSEQ_CPU(x) (&kseq_cpu)
#endif
static void sched_add_internal(struct thread *td, int preemptive);
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_load_add(struct kseq *kseq, struct kse *ke);
static void kseq_load_rem(struct kseq *kseq, struct kse *ke);
static __inline void kseq_runq_add(struct kseq *kseq, struct kse *ke);
static __inline void kseq_runq_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
static int kseq_transfer(struct kseq *ksq, struct kse *ke, int class);
static struct kse *runq_steal(struct runq *rq);
static void sched_balance(void);
static void sched_balance_groups(void);
static void sched_balance_group(struct kseq_group *ksg);
static void sched_balance_pair(struct kseq *high, struct kseq *low);
static void kseq_move(struct kseq *from, int cpu);
static int kseq_idled(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, int stealidle);
/*
* On P4 Xeons the round-robin interrupt delivery is broken. As a result of
* this, we can't pin interrupts to the cpu that they were delivered to,
* otherwise all ithreads only run on CPU 0.
*/
#ifdef __i386__
#define KSE_CAN_MIGRATE(ke, class) \
((ke)->ke_thread->td_pinned == 0 && ((ke)->ke_flags & KEF_BOUND) == 0)
#else /* !__i386__ */
#define KSE_CAN_MIGRATE(ke, class) \
((class) != PRI_ITHD && (ke)->ke_thread->td_pinned == 0 && \
((ke)->ke_flags & KEF_BOUND) == 0)
#endif /* !__i386__ */
#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 TIMESHARE: %d\n", kseq->ksq_load_timeshare);
#ifdef SMP
printf("\tload transferable: %d\n", kseq->ksq_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 __inline void
kseq_runq_add(struct kseq *kseq, struct kse *ke)
{
#ifdef SMP
if (KSE_CAN_MIGRATE(ke, PRI_BASE(ke->ke_ksegrp->kg_pri_class))) {
kseq->ksq_transferable++;
kseq->ksq_group->ksg_transferable++;
ke->ke_flags |= KEF_XFERABLE;
}
#endif
runq_add(ke->ke_runq, ke);
}
static __inline void
kseq_runq_rem(struct kseq *kseq, struct kse *ke)
{
#ifdef SMP
if (ke->ke_flags & KEF_XFERABLE) {
kseq->ksq_transferable--;
kseq->ksq_group->ksg_transferable--;
ke->ke_flags &= ~KEF_XFERABLE;
}
#endif
runq_remove(ke->ke_runq, ke);
}
static void
kseq_load_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++;
kseq->ksq_load++;
if (class != PRI_ITHD && (ke->ke_proc->p_flag & P_NOLOAD) == 0)
#ifdef SMP
kseq->ksq_group->ksg_load++;
#else
kseq->ksq_sysload++;
#endif
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_proc->p_nice, kseq->ksq_nicemin);
if (ke->ke_ksegrp->kg_pri_class == PRI_TIMESHARE)
kseq_nice_add(kseq, ke->ke_proc->p_nice);
}
static void
kseq_load_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--;
if (class != PRI_ITHD && (ke->ke_proc->p_flag & P_NOLOAD) == 0)
#ifdef SMP
kseq->ksq_group->ksg_load--;
#else
kseq->ksq_sysload--;
#endif
kseq->ksq_load--;
ke->ke_runq = NULL;
if (ke->ke_ksegrp->kg_pri_class == PRI_TIMESHARE)
kseq_nice_rem(kseq, ke->ke_proc->p_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
/*
* sched_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
sched_balance(void)
{
struct kseq_group *high;
struct kseq_group *low;
struct kseq_group *ksg;
int cnt;
int i;
if (smp_started == 0)
goto out;
low = high = NULL;
i = random() % (ksg_maxid + 1);
for (cnt = 0; cnt <= ksg_maxid; cnt++) {
ksg = KSEQ_GROUP(i);
/*
* Find the CPU with the highest load that has some
* threads to transfer.
*/
if ((high == NULL || ksg->ksg_load > high->ksg_load)
&& ksg->ksg_transferable)
high = ksg;
if (low == NULL || ksg->ksg_load < low->ksg_load)
low = ksg;
if (++i > ksg_maxid)
i = 0;
}
if (low != NULL && high != NULL && high != low)
sched_balance_pair(LIST_FIRST(&high->ksg_members),
LIST_FIRST(&low->ksg_members));
out:
bal_tick = ticks + (random() % (hz * 2));
}
static void
sched_balance_groups(void)
{
int i;
mtx_assert(&sched_lock, MA_OWNED);
if (smp_started)
for (i = 0; i <= ksg_maxid; i++)
sched_balance_group(KSEQ_GROUP(i));
gbal_tick = ticks + (random() % (hz * 2));
}
static void
sched_balance_group(struct kseq_group *ksg)
{
struct kseq *kseq;
struct kseq *high;
struct kseq *low;
int load;
if (ksg->ksg_transferable == 0)
return;
low = NULL;
high = NULL;
LIST_FOREACH(kseq, &ksg->ksg_members, ksq_siblings) {
load = kseq->ksq_load;
if (high == NULL || load > high->ksq_load)
high = kseq;
if (low == NULL || load < low->ksq_load)
low = kseq;
}
if (high != NULL && low != NULL && high != low)
sched_balance_pair(high, low);
}
static void
sched_balance_pair(struct kseq *high, struct kseq *low)
{
int transferable;
int high_load;
int low_load;
int move;
int diff;
int i;
/*
* If we're transfering within a group we have to use this specific
* kseq's transferable count, otherwise we can steal from other members
* of the group.
*/
if (high->ksq_group == low->ksq_group) {
transferable = high->ksq_transferable;
high_load = high->ksq_load;
low_load = low->ksq_load;
} else {
transferable = high->ksq_group->ksg_transferable;
high_load = high->ksq_group->ksg_load;
low_load = low->ksq_group->ksg_load;
}
if (transferable == 0)
return;
/*
* Determine what the imbalance is and then adjust that to how many
* kses we actually have to give up (transferable).
*/
diff = high_load - low_load;
move = diff / 2;
if (diff & 0x1)
move++;
move = min(move, transferable);
for (i = 0; i < move; i++)
kseq_move(high, KSEQ_ID(low));
return;
}
static void
kseq_move(struct kseq *from, int cpu)
{
struct kseq *kseq;
struct kseq *to;
struct kse *ke;
kseq = from;
to = KSEQ_CPU(cpu);
ke = kseq_steal(kseq, 1);
if (ke == NULL) {
struct kseq_group *ksg;
ksg = kseq->ksq_group;
LIST_FOREACH(kseq, &ksg->ksg_members, ksq_siblings) {
if (kseq == from || kseq->ksq_transferable == 0)
continue;
ke = kseq_steal(kseq, 1);
break;
}
if (ke == NULL)
panic("kseq_move: No KSEs available with a "
"transferable count of %d\n",
ksg->ksg_transferable);
}
if (kseq == to)
return;
ke->ke_state = KES_THREAD;
kseq_runq_rem(kseq, ke);
kseq_load_rem(kseq, ke);
kseq_notify(ke, cpu);
}
static int
kseq_idled(struct kseq *kseq)
{
struct kseq_group *ksg;
struct kseq *steal;
struct kse *ke;
ksg = kseq->ksq_group;
/*
* If we're in a cpu group, try and steal kses from another cpu in
* the group before idling.
*/
if (ksg->ksg_cpus > 1 && ksg->ksg_transferable) {
LIST_FOREACH(steal, &ksg->ksg_members, ksq_siblings) {
if (steal == kseq || steal->ksq_transferable == 0)
continue;
ke = kseq_steal(steal, 0);
if (ke == NULL)
continue;
ke->ke_state = KES_THREAD;
kseq_runq_rem(steal, ke);
kseq_load_rem(steal, ke);
ke->ke_cpu = PCPU_GET(cpuid);
sched_add_internal(ke->ke_thread, 0);
return (0);
}
}
/*
* We only set the idled bit when all of the cpus in the group are
* idle. Otherwise we could get into a situation where a KSE bounces
* back and forth between two idle cores on seperate physical CPUs.
*/
ksg->ksg_idlemask |= PCPU_GET(cpumask);
if (ksg->ksg_idlemask != ksg->ksg_cpumask)
return (1);
atomic_set_int(&kseq_idle, ksg->ksg_mask);
return (1);
}
static void
kseq_assign(struct kseq *kseq)
{
struct kse *nke;
struct kse *ke;
do {
*(volatile struct kse **)&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_internal(ke->ke_thread, 0);
}
}
static void
kseq_notify(struct kse *ke, int cpu)
{
struct kseq *kseq;
struct thread *td;
struct pcpu *pcpu;
int prio;
ke->ke_cpu = cpu;
ke->ke_flags |= KEF_ASSIGNED;
prio = ke->ke_thread->td_priority;
kseq = KSEQ_CPU(cpu);
/*
* Place a KSE on another cpu's queue and force a resched.
*/
do {
*(volatile struct kse **)&ke->ke_assign = kseq->ksq_assigned;
} while(!atomic_cmpset_ptr(&kseq->ksq_assigned, ke->ke_assign, ke));
/*
* Without sched_lock we could lose a race where we set NEEDRESCHED
* on a thread that is switched out before the IPI is delivered. This
* would lead us to miss the resched. This will be a problem once
* sched_lock is pushed down.
*/
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] & (1ul << 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, int stealidle)
{
struct kse *ke;
/*
* Steal from next first to try to get a non-interactive task that
* may not have run for a while.
*/
if ((ke = runq_steal(kseq->ksq_next)) != NULL)
return (ke);
if ((ke = runq_steal(kseq->ksq_curr)) != NULL)
return (ke);
if (stealidle)
return (runq_steal(&kseq->ksq_idle));
return (NULL);
}
int
kseq_transfer(struct kseq *kseq, struct kse *ke, int class)
{
struct kseq_group *ksg;
int cpu;
if (smp_started == 0)
return (0);
cpu = 0;
/*
* If our load exceeds a certain threshold we should attempt to
* reassign this thread. The first candidate is the cpu that
* originally ran the thread. If it is idle, assign it there,
* otherwise, pick an idle cpu.
*
* The threshold at which we start to reassign kses has a large impact
* on the overall performance of the system. Tuned too high and
* some CPUs may idle. Too low and there will be excess migration
* and context switches.
*/
ksg = kseq->ksq_group;
if (ksg->ksg_load > ksg->ksg_cpus && kseq_idle) {
ksg = KSEQ_CPU(ke->ke_cpu)->ksq_group;
if (kseq_idle & ksg->ksg_mask) {
cpu = ffs(ksg->ksg_idlemask);
if (cpu)
goto migrate;
}
/*
* Multiple cpus could find this bit simultaneously
* but the race shouldn't be terrible.
*/
cpu = ffs(kseq_idle);
if (cpu)
goto migrate;
}
/*
* If another cpu in this group has idled, assign a thread over
* to them after checking to see if there are idled groups.
*/
ksg = kseq->ksq_group;
if (ksg->ksg_idlemask) {
cpu = ffs(ksg->ksg_idlemask);
if (cpu)
goto migrate;
}
/*
* No new CPU was found.
*/
return (0);
migrate:
/*
* Now that we've found an idle CPU, migrate the thread.
*/
cpu--;
ke->ke_runq = NULL;
kseq_notify(ke, cpu);
return (1);
}
#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 swapped 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;
}
static void
sched_setup(void *dummy)
{
#ifdef SMP
int balance_groups;
int i;
#endif
slice_min = (hz/100); /* 10ms */
slice_max = (hz/7); /* ~140ms */
#ifdef SMP
balance_groups = 0;
/*
* Initialize the kseqs.
*/
for (i = 0; i < MAXCPU; i++) {
struct kseq *ksq;
ksq = &kseq_cpu[i];
ksq->ksq_assigned = NULL;
kseq_setup(&kseq_cpu[i]);
}
if (smp_topology == NULL) {
struct kseq_group *ksg;
struct kseq *ksq;
for (i = 0; i < MAXCPU; i++) {
ksq = &kseq_cpu[i];
ksg = &kseq_groups[i];
/*
* Setup a kseq group with one member.
*/
ksq->ksq_transferable = 0;
ksq->ksq_group = ksg;
ksg->ksg_cpus = 1;
ksg->ksg_idlemask = 0;
ksg->ksg_cpumask = ksg->ksg_mask = 1 << i;
ksg->ksg_load = 0;
ksg->ksg_transferable = 0;
LIST_INIT(&ksg->ksg_members);
LIST_INSERT_HEAD(&ksg->ksg_members, ksq, ksq_siblings);
}
} else {
struct kseq_group *ksg;
struct cpu_group *cg;
int j;
for (i = 0; i < smp_topology->ct_count; i++) {
cg = &smp_topology->ct_group[i];
ksg = &kseq_groups[i];
/*
* Initialize the group.
*/
ksg->ksg_idlemask = 0;
ksg->ksg_load = 0;
ksg->ksg_transferable = 0;
ksg->ksg_cpus = cg->cg_count;
ksg->ksg_cpumask = cg->cg_mask;
LIST_INIT(&ksg->ksg_members);
/*
* Find all of the group members and add them.
*/
for (j = 0; j < MAXCPU; j++) {
if ((cg->cg_mask & (1 << j)) != 0) {
if (ksg->ksg_mask == 0)
ksg->ksg_mask = 1 << j;
kseq_cpu[j].ksq_transferable = 0;
kseq_cpu[j].ksq_group = ksg;
LIST_INSERT_HEAD(&ksg->ksg_members,
&kseq_cpu[j], ksq_siblings);
}
}
if (ksg->ksg_cpus > 1)
balance_groups = 1;
}
ksg_maxid = smp_topology->ct_count - 1;
}
/*
* Stagger the group and global load balancer so they do not
* interfere with each other.
*/
bal_tick = ticks + hz;
if (balance_groups)
gbal_tick = ticks + (hz / 2);
#else
kseq_setup(KSEQ_SELF());
#endif
mtx_lock_spin(&sched_lock);
kseq_load_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_proc->p_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 a minimal 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_proc->p_nice + (0 - kseq->ksq_nicemin);
if (kseq->ksq_load_timeshare == 0 ||
kg->kg_proc->p_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_proc->p_nice == 0)
ke->ke_slice = SCHED_SLICE_MIN;
else
ke->ke_slice = 0;
} else
ke->ke_slice = SCHED_SLICE_INTERACTIVE;
CTR6(KTR_ULE,
"Sliced %p(%d) (nice: %d, nicemin: %d, load: %d, interactive: %d)",
ke, ke->ke_slice, kg->kg_proc->p_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 [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
*/
if (sum > (SCHED_SLP_RUN_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;
}
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;
td->td_pflags &= ~TDP_OWEPREEMPT;
/*
* If the KSE has been assigned it may be in the process of switching
* to the new cpu. This is the case in sched_bind().
*/
if ((ke->ke_flags & KEF_ASSIGNED) == 0) {
if (td == PCPU_GET(idlethread)) {
TD_SET_CAN_RUN(td);
} else if (TD_IS_RUNNING(td)) {
kseq_load_rem(KSEQ_CPU(ke->ke_cpu), ke);
setrunqueue(td);
} else {
if (ke->ke_runq) {
kseq_load_rem(KSEQ_CPU(ke->ke_cpu), ke);
} else if ((td->td_flags & TDF_IDLETD) == 0)
kdb_backtrace();
/*
* 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);
}
}
if (newtd != NULL) {
kseq_load_add(KSEQ_SELF(), newtd->td_kse);
ke->ke_cpu = PCPU_GET(cpuid);
ke->ke_runq = KSEQ_SELF()->ksq_curr;
} else
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 proc *p, int nice)
{
struct ksegrp *kg;
struct kse *ke;
struct thread *td;
struct kseq *kseq;
PROC_LOCK_ASSERT(p, MA_OWNED);
mtx_assert(&sched_lock, MA_OWNED);
/*
* We need to adjust the nice counts for running KSEs.
*/
FOREACH_KSEGRP_IN_PROC(p, kg) {
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, p->p_nice);
kseq_nice_add(kseq, nice);
}
}
}
p->p_nice = nice;
FOREACH_KSEGRP_IN_PROC(p, kg) {
sched_priority(kg);
FOREACH_THREAD_IN_GROUP(kg, td)
td->td_flags |= TDF_NEEDRESCHED;
}
}
void
sched_sleep(struct thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_slptime = ticks;
td->td_base_pri = td->td_priority;
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 thread *td, struct proc *p1)
{
mtx_assert(&sched_lock, MA_OWNED);
p1->p_nice = td->td_proc->p_nice;
sched_fork_ksegrp(td, FIRST_KSEGRP_IN_PROC(p1));
sched_fork_kse(td, FIRST_KSE_IN_PROC(p1));
sched_fork_thread(td, FIRST_THREAD_IN_PROC(p1));
}
void
sched_fork_kse(struct thread *td, struct kse *child)
{
struct kse *ke = td->td_kse;
child->ke_slice = 1; /* Attempt to quickly learn interactivity. */
child->ke_cpu = ke->ke_cpu;
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 thread *td, struct ksegrp *child)
{
struct ksegrp *kg = td->td_ksegrp;
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;
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
/*
* On SMP if we're on the RUNQ we must adjust the transferable
* count because could be changing to or from an interrupt
* class.
*/
if (ke->ke_state == KES_ONRUNQ) {
if (KSE_CAN_MIGRATE(ke, oclass)) {
kseq->ksq_transferable--;
kseq->ksq_group->ksg_transferable--;
}
if (KSE_CAN_MIGRATE(ke, nclass)) {
kseq->ksq_transferable++;
kseq->ksq_group->ksg_transferable++;
}
}
#endif
if (oclass == PRI_TIMESHARE) {
kseq->ksq_load_timeshare--;
kseq_nice_rem(kseq, kg->kg_proc->p_nice);
}
if (nclass == PRI_TIMESHARE) {
kseq->ksq_load_timeshare++;
kseq_nice_add(kseq, kg->kg_proc->p_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 thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
sched_exit_kse(FIRST_KSE_IN_PROC(p), td);
sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), td);
}
void
sched_exit_kse(struct kse *ke, struct thread *td)
{
kseq_load_rem(KSEQ_CPU(td->td_kse->ke_cpu), td->td_kse);
}
void
sched_exit_ksegrp(struct ksegrp *kg, struct thread *td)
{
/* kg->kg_slptime += td->td_ksegrp->kg_slptime; */
kg->kg_runtime += td->td_ksegrp->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;
mtx_assert(&sched_lock, MA_OWNED);
kseq = KSEQ_SELF();
#ifdef SMP
if (ticks == bal_tick)
sched_balance();
if (ticks == gbal_tick)
sched_balance_groups();
/*
* We could have been assigned a non real-time thread without an
* IPI.
*/
if (kseq->ksq_assigned)
kseq_assign(kseq); /* Potentially sets NEEDRESCHED */
#endif
/*
* 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;
/* 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.
*/
if (--ke->ke_slice > 0)
return;
/*
* We're out of time, recompute priorities and requeue.
*/
kseq_load_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_load_add(kseq, ke);
td->td_flags |= TDF_NEEDRESCHED;
}
int
sched_runnable(void)
{
struct kseq *kseq;
int load;
load = 1;
kseq = KSEQ_SELF();
#ifdef SMP
if (kseq->ksq_assigned) {
mtx_lock_spin(&sched_lock);
kseq_assign(kseq);
mtx_unlock_spin(&sched_lock);
}
#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:
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
restart:
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)
if (kseq_idled(kseq) == 0)
goto restart;
#endif
kseq_runq_rem(kseq, 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
if (kseq_idled(kseq) == 0)
goto restart;
#endif
return (NULL);
}
void
sched_add(struct thread *td)
{
sched_add_internal(td, 1);
}
static void
sched_add_internal(struct thread *td, int preemptive)
{
struct kseq *kseq;
struct ksegrp *kg;
struct kse *ke;
#ifdef SMP
int canmigrate;
#endif
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:
if (SCHED_CURR(kg, ke))
ke->ke_runq = kseq->ksq_curr;
else
ke->ke_runq = kseq->ksq_next;
break;
case PRI_IDLE:
/*
* 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
/*
* Don't migrate running threads here. Force the long term balancer
* to do it.
*/
canmigrate = KSE_CAN_MIGRATE(ke, class);
if (TD_IS_RUNNING(td))
canmigrate = 0;
/*
* If this thread is pinned or bound, notify the target cpu.
*/
if (!canmigrate && ke->ke_cpu != PCPU_GET(cpuid) ) {
ke->ke_runq = NULL;
kseq_notify(ke, ke->ke_cpu);
return;
}
/*
* If we had been idle, clear our bit in the group and potentially
* the global bitmap. If not, see if we should transfer this thread.
*/
if ((class == PRI_TIMESHARE || class == PRI_REALTIME) &&
(kseq->ksq_group->ksg_idlemask & PCPU_GET(cpumask)) != 0) {
/*
* Check to see if our group is unidling, and if so, remove it
* from the global idle mask.
*/
if (kseq->ksq_group->ksg_idlemask ==
kseq->ksq_group->ksg_cpumask)
atomic_clear_int(&kseq_idle, kseq->ksq_group->ksg_mask);
/*
* Now remove ourselves from the group specific idle mask.
*/
kseq->ksq_group->ksg_idlemask &= ~PCPU_GET(cpumask);
} else if (kseq->ksq_load > 1 && canmigrate)
if (kseq_transfer(kseq, ke, class))
return;
ke->ke_cpu = PCPU_GET(cpuid);
#endif
/*
* XXX With preemption this is not necessary.
*/
if (td->td_priority < curthread->td_priority)
curthread->td_flags |= TDF_NEEDRESCHED;
if (preemptive && maybe_preempt(td))
return;
ke->ke_ksegrp->kg_runq_kses++;
ke->ke_state = KES_ONRUNQ;
kseq_runq_add(kseq, ke);
kseq_load_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),
("sched_rem: KSE not on run queue"));
ke->ke_state = KES_THREAD;
ke->ke_ksegrp->kg_runq_kses--;
kseq = KSEQ_CPU(ke->ke_cpu);
kseq_runq_rem(kseq, ke);
kseq_load_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_ftick + SCHED_CPU_TICKS < ke->ke_ltick ||
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_bind(struct thread *td, int cpu)
{
struct kse *ke;
mtx_assert(&sched_lock, MA_OWNED);
ke = td->td_kse;
ke->ke_flags |= KEF_BOUND;
#ifdef SMP
if (PCPU_GET(cpuid) == cpu)
return;
/* sched_rem without the runq_remove */
ke->ke_state = KES_THREAD;
ke->ke_ksegrp->kg_runq_kses--;
kseq_load_rem(KSEQ_CPU(ke->ke_cpu), ke);
kseq_notify(ke, cpu);
/* When we return from mi_switch we'll be on the correct cpu. */
mi_switch(SW_VOL, NULL);
#endif
}
void
sched_unbind(struct thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_kse->ke_flags &= ~KEF_BOUND;
}
int
sched_load(void)
{
#ifdef SMP
int total;
int i;
total = 0;
for (i = 0; i <= ksg_maxid; i++)
total += KSEQ_GROUP(i)->ksg_load;
return (total);
#else
return (KSEQ_SELF()->ksq_sysload);
#endif
}
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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