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freebsd-dev/sys/kern/sched_ule.c
Jeff Roberson dda713dfb8 - Fix an off by one error in sched_pri_range. 
- In tdq_choose() only assert that a thread does not have too high a
   priority (low value) for the queue we removed it from.  This will catch
   bugs in priority elevation.  It's not a serious error for the thread
   to have too low a priority as we don't change queues in this case as
   an optimization.

Reported by:	kris
2007-06-15 19:33:58 +00:00

2187 lines
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/*-
* Copyright (c) 2002-2007, 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 "opt_hwpmc_hooks.h"
#include "opt_sched.h"
#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/turnstile.h>
#include <sys/umtx.h>
#include <sys/vmmeter.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
#ifdef HWPMC_HOOKS
#include <sys/pmckern.h>
#endif
#include <machine/cpu.h>
#include <machine/smp.h>
#ifndef PREEMPTION
#error "SCHED_ULE requires options PREEMPTION"
#endif
/*
* TODO:
* Pick idle from affinity group or self group first.
* Implement pick_score.
*/
#define KTR_ULE 0x0 /* Enable for pickpri debugging. */
/*
* Thread scheduler specific section.
*/
struct td_sched {
TAILQ_ENTRY(td_sched) ts_procq; /* (j/z) Run queue. */
int ts_flags; /* (j) TSF_* flags. */
struct thread *ts_thread; /* (*) Active associated thread. */
u_char ts_rqindex; /* (j) Run queue index. */
int ts_slptime;
int ts_slice;
struct runq *ts_runq;
u_char ts_cpu; /* CPU that we have affinity for. */
/* The following variables are only used for pctcpu calculation */
int ts_ltick; /* Last tick that we were running on */
int ts_ftick; /* First tick that we were running on */
int ts_ticks; /* Tick count */
#ifdef SMP
int ts_rltick; /* Real last tick, for affinity. */
#endif
/* originally from kg_sched */
u_int skg_slptime; /* Number of ticks we vol. slept */
u_int skg_runtime; /* Number of ticks we were running */
};
/* flags kept in ts_flags */
#define TSF_BOUND 0x0001 /* Thread can not migrate. */
#define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */
static struct td_sched td_sched0;
/*
* Cpu percentage computation macros and defines.
*
* SCHED_TICK_SECS: Number of seconds to average the cpu usage across.
* SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across.
* SCHED_TICK_MAX: Maximum number of ticks before scaling back.
* SCHED_TICK_SHIFT: Shift factor to avoid rounding away results.
* SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count.
* SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks.
*/
#define SCHED_TICK_SECS 10
#define SCHED_TICK_TARG (hz * SCHED_TICK_SECS)
#define SCHED_TICK_MAX (SCHED_TICK_TARG + hz)
#define SCHED_TICK_SHIFT 10
#define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT)
#define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz))
/*
* These macros determine priorities for non-interactive threads. They are
* assigned a priority based on their recent cpu utilization as expressed
* by the ratio of ticks to the tick total. NHALF priorities at the start
* and end of the MIN to MAX timeshare range are only reachable with negative
* or positive nice respectively.
*
* PRI_RANGE: Priority range for utilization dependent priorities.
* PRI_NRESV: Number of nice values.
* PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total.
* PRI_NICE: Determines the part of the priority inherited from nice.
*/
#define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN)
#define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
#define SCHED_PRI_MIN (PRI_MIN_TIMESHARE + SCHED_PRI_NHALF)
#define SCHED_PRI_MAX (PRI_MAX_TIMESHARE - SCHED_PRI_NHALF)
#define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN)
#define SCHED_PRI_TICKS(ts) \
(SCHED_TICK_HZ((ts)) / \
(roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE))
#define SCHED_PRI_NICE(nice) (nice)
/*
* These determine the interactivity of a process. Interactivity differs from
* cpu utilization in that it expresses the voluntary time slept vs time ran
* while cpu utilization includes all time not running. This more accurately
* models the intent of the thread.
*
* 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) << SCHED_TICK_SHIFT)
#define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT)
#define SCHED_INTERACT_MAX (100)
#define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
#define SCHED_INTERACT_THRESH (30)
/*
* tickincr: Converts a stathz tick into a hz domain scaled by
* the shift factor. Without the shift the error rate
* due to rounding would be unacceptably high.
* realstathz: stathz is sometimes 0 and run off of hz.
* sched_slice: Runtime of each thread before rescheduling.
*/
static int sched_interact = SCHED_INTERACT_THRESH;
static int realstathz;
static int tickincr;
static int sched_slice;
/*
* tdq - per processor runqs and statistics.
*/
struct tdq {
struct runq tdq_idle; /* Queue of IDLE threads. */
struct runq tdq_timeshare; /* timeshare run queue. */
struct runq tdq_realtime; /* real-time run queue. */
u_char tdq_idx; /* Current insert index. */
u_char tdq_ridx; /* Current removal index. */
short tdq_flags; /* Thread queue flags */
int tdq_load; /* Aggregate load. */
#ifdef SMP
int tdq_transferable;
LIST_ENTRY(tdq) tdq_siblings; /* Next in tdq group. */
struct tdq_group *tdq_group; /* Our processor group. */
#else
int tdq_sysload; /* For loadavg, !ITHD load. */
#endif
};
#define TDQF_BUSY 0x0001 /* Queue is marked as busy */
#ifdef SMP
/*
* tdq 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 tdq_group {
int tdg_cpus; /* Count of CPUs in this tdq group. */
cpumask_t tdg_cpumask; /* Mask of cpus in this group. */
cpumask_t tdg_idlemask; /* Idle cpus in this group. */
cpumask_t tdg_mask; /* Bit mask for first cpu. */
int tdg_load; /* Total load of this group. */
int tdg_transferable; /* Transferable load of this group. */
LIST_HEAD(, tdq) tdg_members; /* Linked list of all members. */
};
#define SCHED_AFFINITY_DEFAULT (hz / 100)
#define SCHED_AFFINITY(ts) ((ts)->ts_rltick > ticks - affinity)
/*
* Run-time tunables.
*/
static int rebalance = 0;
static int pick_pri = 0;
static int affinity;
static int tryself = 1;
static int tryselfidle = 1;
static int ipi_ast = 0;
static int ipi_preempt = 1;
static int ipi_thresh = PRI_MIN_KERN;
static int steal_htt = 1;
static int steal_busy = 1;
static int busy_thresh = 4;
static int topology = 0;
/*
* One thread queue per processor.
*/
static volatile cpumask_t tdq_idle;
static volatile cpumask_t tdq_busy;
static int tdg_maxid;
static struct tdq tdq_cpu[MAXCPU];
static struct tdq_group tdq_groups[MAXCPU];
static int bal_tick;
static int gbal_tick;
static int balance_groups;
#define TDQ_SELF() (&tdq_cpu[PCPU_GET(cpuid)])
#define TDQ_CPU(x) (&tdq_cpu[(x)])
#define TDQ_ID(x) ((x) - tdq_cpu)
#define TDQ_GROUP(x) (&tdq_groups[(x)])
#else /* !SMP */
static struct tdq tdq_cpu;
#define TDQ_ID(x) (0)
#define TDQ_SELF() (&tdq_cpu)
#define TDQ_CPU(x) (&tdq_cpu)
#endif
static void sched_priority(struct thread *);
static void sched_thread_priority(struct thread *, u_char);
static int sched_interact_score(struct thread *);
static void sched_interact_update(struct thread *);
static void sched_interact_fork(struct thread *);
static void sched_pctcpu_update(struct td_sched *);
static inline void sched_pin_td(struct thread *td);
static inline void sched_unpin_td(struct thread *td);
/* Operations on per processor queues */
static struct td_sched * tdq_choose(struct tdq *);
static void tdq_setup(struct tdq *);
static void tdq_load_add(struct tdq *, struct td_sched *);
static void tdq_load_rem(struct tdq *, struct td_sched *);
static __inline void tdq_runq_add(struct tdq *, struct td_sched *, int);
static __inline void tdq_runq_rem(struct tdq *, struct td_sched *);
void tdq_print(int cpu);
static void runq_print(struct runq *rq);
#ifdef SMP
static int tdq_pickidle(struct tdq *, struct td_sched *);
static int tdq_pickpri(struct tdq *, struct td_sched *, int);
static struct td_sched *runq_steal(struct runq *);
static void sched_balance(void);
static void sched_balance_groups(void);
static void sched_balance_group(struct tdq_group *);
static void sched_balance_pair(struct tdq *, struct tdq *);
static void sched_smp_tick(struct thread *);
static void tdq_move(struct tdq *, int);
static int tdq_idled(struct tdq *);
static void tdq_notify(struct td_sched *);
static struct td_sched *tdq_steal(struct tdq *, int);
#define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0)
#endif
static void sched_setup(void *dummy);
SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL)
static void sched_initticks(void *dummy);
SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks, NULL)
static inline void
sched_pin_td(struct thread *td)
{
td->td_pinned++;
}
static inline void
sched_unpin_td(struct thread *td)
{
td->td_pinned--;
}
static void
runq_print(struct runq *rq)
{
struct rqhead *rqh;
struct td_sched *ts;
int pri;
int j;
int i;
for (i = 0; i < RQB_LEN; i++) {
printf("\t\trunq bits %d 0x%zx\n",
i, rq->rq_status.rqb_bits[i]);
for (j = 0; j < RQB_BPW; j++)
if (rq->rq_status.rqb_bits[i] & (1ul << j)) {
pri = j + (i << RQB_L2BPW);
rqh = &rq->rq_queues[pri];
TAILQ_FOREACH(ts, rqh, ts_procq) {
printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n",
ts->ts_thread, ts->ts_thread->td_proc->p_comm, ts->ts_thread->td_priority, ts->ts_rqindex, pri);
}
}
}
}
void
tdq_print(int cpu)
{
struct tdq *tdq;
tdq = TDQ_CPU(cpu);
printf("tdq:\n");
printf("\tload: %d\n", tdq->tdq_load);
printf("\ttimeshare idx: %d\n", tdq->tdq_idx);
printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx);
printf("\trealtime runq:\n");
runq_print(&tdq->tdq_realtime);
printf("\ttimeshare runq:\n");
runq_print(&tdq->tdq_timeshare);
printf("\tidle runq:\n");
runq_print(&tdq->tdq_idle);
#ifdef SMP
printf("\tload transferable: %d\n", tdq->tdq_transferable);
#endif
}
static __inline void
tdq_runq_add(struct tdq *tdq, struct td_sched *ts, int flags)
{
#ifdef SMP
if (THREAD_CAN_MIGRATE(ts->ts_thread)) {
tdq->tdq_transferable++;
tdq->tdq_group->tdg_transferable++;
ts->ts_flags |= TSF_XFERABLE;
if (tdq->tdq_transferable >= busy_thresh &&
(tdq->tdq_flags & TDQF_BUSY) == 0) {
tdq->tdq_flags |= TDQF_BUSY;
atomic_set_int(&tdq_busy, 1 << TDQ_ID(tdq));
}
}
#endif
if (ts->ts_runq == &tdq->tdq_timeshare) {
u_char pri;
pri = ts->ts_thread->td_priority;
KASSERT(pri <= PRI_MAX_TIMESHARE && pri >= PRI_MIN_TIMESHARE,
("Invalid priority %d on timeshare runq", pri));
/*
* This queue contains only priorities between MIN and MAX
* realtime. Use the whole queue to represent these values.
*/
#define TS_RQ_PPQ (((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) + 1) / RQ_NQS)
if ((flags & SRQ_BORROWING) == 0) {
pri = (pri - PRI_MIN_TIMESHARE) / TS_RQ_PPQ;
pri = (pri + tdq->tdq_idx) % RQ_NQS;
/*
* This effectively shortens the queue by one so we
* can have a one slot difference between idx and
* ridx while we wait for threads to drain.
*/
if (tdq->tdq_ridx != tdq->tdq_idx &&
pri == tdq->tdq_ridx)
pri = (unsigned char)(pri - 1) % RQ_NQS;
} else
pri = tdq->tdq_ridx;
runq_add_pri(ts->ts_runq, ts, pri, flags);
} else
runq_add(ts->ts_runq, ts, flags);
}
static __inline void
tdq_runq_rem(struct tdq *tdq, struct td_sched *ts)
{
#ifdef SMP
if (ts->ts_flags & TSF_XFERABLE) {
tdq->tdq_transferable--;
tdq->tdq_group->tdg_transferable--;
ts->ts_flags &= ~TSF_XFERABLE;
if (tdq->tdq_transferable < busy_thresh &&
(tdq->tdq_flags & TDQF_BUSY)) {
atomic_clear_int(&tdq_busy, 1 << TDQ_ID(tdq));
tdq->tdq_flags &= ~TDQF_BUSY;
}
}
#endif
if (ts->ts_runq == &tdq->tdq_timeshare) {
if (tdq->tdq_idx != tdq->tdq_ridx)
runq_remove_idx(ts->ts_runq, ts, &tdq->tdq_ridx);
else
runq_remove_idx(ts->ts_runq, ts, NULL);
/*
* For timeshare threads we update the priority here so
* the priority reflects the time we've been sleeping.
*/
ts->ts_ltick = ticks;
sched_pctcpu_update(ts);
sched_priority(ts->ts_thread);
} else
runq_remove(ts->ts_runq, ts);
}
static void
tdq_load_add(struct tdq *tdq, struct td_sched *ts)
{
int class;
mtx_assert(&sched_lock, MA_OWNED);
class = PRI_BASE(ts->ts_thread->td_pri_class);
tdq->tdq_load++;
CTR2(KTR_SCHED, "cpu %jd load: %d", TDQ_ID(tdq), tdq->tdq_load);
if (class != PRI_ITHD &&
(ts->ts_thread->td_proc->p_flag & P_NOLOAD) == 0)
#ifdef SMP
tdq->tdq_group->tdg_load++;
#else
tdq->tdq_sysload++;
#endif
}
static void
tdq_load_rem(struct tdq *tdq, struct td_sched *ts)
{
int class;
mtx_assert(&sched_lock, MA_OWNED);
class = PRI_BASE(ts->ts_thread->td_pri_class);
if (class != PRI_ITHD &&
(ts->ts_thread->td_proc->p_flag & P_NOLOAD) == 0)
#ifdef SMP
tdq->tdq_group->tdg_load--;
#else
tdq->tdq_sysload--;
#endif
tdq->tdq_load--;
CTR1(KTR_SCHED, "load: %d", tdq->tdq_load);
ts->ts_runq = NULL;
}
#ifdef SMP
static void
sched_smp_tick(struct thread *td)
{
struct tdq *tdq;
tdq = TDQ_SELF();
if (rebalance) {
if (ticks >= bal_tick)
sched_balance();
if (ticks >= gbal_tick && balance_groups)
sched_balance_groups();
}
td->td_sched->ts_rltick = ticks;
}
/*
* 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 tdq_group *high;
struct tdq_group *low;
struct tdq_group *tdg;
int cnt;
int i;
bal_tick = ticks + (random() % (hz * 2));
if (smp_started == 0)
return;
low = high = NULL;
i = random() % (tdg_maxid + 1);
for (cnt = 0; cnt <= tdg_maxid; cnt++) {
tdg = TDQ_GROUP(i);
/*
* Find the CPU with the highest load that has some
* threads to transfer.
*/
if ((high == NULL || tdg->tdg_load > high->tdg_load)
&& tdg->tdg_transferable)
high = tdg;
if (low == NULL || tdg->tdg_load < low->tdg_load)
low = tdg;
if (++i > tdg_maxid)
i = 0;
}
if (low != NULL && high != NULL && high != low)
sched_balance_pair(LIST_FIRST(&high->tdg_members),
LIST_FIRST(&low->tdg_members));
}
static void
sched_balance_groups(void)
{
int i;
gbal_tick = ticks + (random() % (hz * 2));
mtx_assert(&sched_lock, MA_OWNED);
if (smp_started)
for (i = 0; i <= tdg_maxid; i++)
sched_balance_group(TDQ_GROUP(i));
}
static void
sched_balance_group(struct tdq_group *tdg)
{
struct tdq *tdq;
struct tdq *high;
struct tdq *low;
int load;
if (tdg->tdg_transferable == 0)
return;
low = NULL;
high = NULL;
LIST_FOREACH(tdq, &tdg->tdg_members, tdq_siblings) {
load = tdq->tdq_load;
if (high == NULL || load > high->tdq_load)
high = tdq;
if (low == NULL || load < low->tdq_load)
low = tdq;
}
if (high != NULL && low != NULL && high != low)
sched_balance_pair(high, low);
}
static void
sched_balance_pair(struct tdq *high, struct tdq *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
* tdq's transferable count, otherwise we can steal from other members
* of the group.
*/
if (high->tdq_group == low->tdq_group) {
transferable = high->tdq_transferable;
high_load = high->tdq_load;
low_load = low->tdq_load;
} else {
transferable = high->tdq_group->tdg_transferable;
high_load = high->tdq_group->tdg_load;
low_load = low->tdq_group->tdg_load;
}
if (transferable == 0)
return;
/*
* Determine what the imbalance is and then adjust that to how many
* threads 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++)
tdq_move(high, TDQ_ID(low));
return;
}
static void
tdq_move(struct tdq *from, int cpu)
{
struct tdq *tdq;
struct tdq *to;
struct td_sched *ts;
tdq = from;
to = TDQ_CPU(cpu);
ts = tdq_steal(tdq, 1);
if (ts == NULL) {
struct tdq_group *tdg;
tdg = tdq->tdq_group;
LIST_FOREACH(tdq, &tdg->tdg_members, tdq_siblings) {
if (tdq == from || tdq->tdq_transferable == 0)
continue;
ts = tdq_steal(tdq, 1);
break;
}
if (ts == NULL)
panic("tdq_move: No threads available with a "
"transferable count of %d\n",
tdg->tdg_transferable);
}
if (tdq == to)
return;
sched_rem(ts->ts_thread);
ts->ts_cpu = cpu;
sched_pin_td(ts->ts_thread);
sched_add(ts->ts_thread, SRQ_YIELDING);
sched_unpin_td(ts->ts_thread);
}
static int
tdq_idled(struct tdq *tdq)
{
struct tdq_group *tdg;
struct tdq *steal;
struct td_sched *ts;
tdg = tdq->tdq_group;
/*
* If we're in a cpu group, try and steal threads from another cpu in
* the group before idling.
*/
if (steal_htt && tdg->tdg_cpus > 1 && tdg->tdg_transferable) {
LIST_FOREACH(steal, &tdg->tdg_members, tdq_siblings) {
if (steal == tdq || steal->tdq_transferable == 0)
continue;
ts = tdq_steal(steal, 0);
if (ts)
goto steal;
}
}
if (steal_busy) {
while (tdq_busy) {
int cpu;
cpu = ffs(tdq_busy);
if (cpu == 0)
break;
cpu--;
steal = TDQ_CPU(cpu);
if (steal->tdq_transferable == 0)
continue;
ts = tdq_steal(steal, 1);
if (ts == NULL)
continue;
CTR5(KTR_ULE,
"tdq_idled: stealing td %p(%s) pri %d from %d busy 0x%X",
ts->ts_thread, ts->ts_thread->td_proc->p_comm,
ts->ts_thread->td_priority, cpu, tdq_busy);
goto steal;
}
}
/*
* 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 thread bounces
* back and forth between two idle cores on seperate physical CPUs.
*/
tdg->tdg_idlemask |= PCPU_GET(cpumask);
if (tdg->tdg_idlemask == tdg->tdg_cpumask)
atomic_set_int(&tdq_idle, tdg->tdg_mask);
return (1);
steal:
sched_rem(ts->ts_thread);
ts->ts_cpu = PCPU_GET(cpuid);
sched_pin_td(ts->ts_thread);
sched_add(ts->ts_thread, SRQ_YIELDING);
sched_unpin_td(ts->ts_thread);
return (0);
}
static void
tdq_notify(struct td_sched *ts)
{
struct thread *ctd;
struct pcpu *pcpu;
int cpri;
int pri;
int cpu;
cpu = ts->ts_cpu;
pri = ts->ts_thread->td_priority;
pcpu = pcpu_find(cpu);
ctd = pcpu->pc_curthread;
cpri = ctd->td_priority;
/*
* If our priority is not better than the current priority there is
* nothing to do.
*/
if (pri > cpri)
return;
/*
* Always IPI idle.
*/
if (cpri > PRI_MIN_IDLE)
goto sendipi;
/*
* If we're realtime or better and there is timeshare or worse running
* send an IPI.
*/
if (pri < PRI_MAX_REALTIME && cpri > PRI_MAX_REALTIME)
goto sendipi;
/*
* Otherwise only IPI if we exceed the threshold.
*/
if (pri > ipi_thresh)
return;
sendipi:
ctd->td_flags |= TDF_NEEDRESCHED;
if (cpri < PRI_MIN_IDLE) {
if (ipi_ast)
ipi_selected(1 << cpu, IPI_AST);
else if (ipi_preempt)
ipi_selected(1 << cpu, IPI_PREEMPT);
} else
ipi_selected(1 << cpu, IPI_PREEMPT);
}
static struct td_sched *
runq_steal(struct runq *rq)
{
struct rqhead *rqh;
struct rqbits *rqb;
struct td_sched *ts;
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(ts, rqh, ts_procq) {
if (THREAD_CAN_MIGRATE(ts->ts_thread))
return (ts);
}
}
}
return (NULL);
}
static struct td_sched *
tdq_steal(struct tdq *tdq, int stealidle)
{
struct td_sched *ts;
/*
* Steal from next first to try to get a non-interactive task that
* may not have run for a while.
* XXX Need to effect steal order for timeshare threads.
*/
if ((ts = runq_steal(&tdq->tdq_realtime)) != NULL)
return (ts);
if ((ts = runq_steal(&tdq->tdq_timeshare)) != NULL)
return (ts);
if (stealidle)
return (runq_steal(&tdq->tdq_idle));
return (NULL);
}
int
tdq_pickidle(struct tdq *tdq, struct td_sched *ts)
{
struct tdq_group *tdg;
int self;
int cpu;
self = PCPU_GET(cpuid);
if (smp_started == 0)
return (self);
/*
* If the current CPU has idled, just run it here.
*/
if ((tdq->tdq_group->tdg_idlemask & PCPU_GET(cpumask)) != 0)
return (self);
/*
* Try the last group we ran on.
*/
tdg = TDQ_CPU(ts->ts_cpu)->tdq_group;
cpu = ffs(tdg->tdg_idlemask);
if (cpu)
return (cpu - 1);
/*
* Search for an idle group.
*/
cpu = ffs(tdq_idle);
if (cpu)
return (cpu - 1);
/*
* XXX If there are no idle groups, check for an idle core.
*/
/*
* No idle CPUs?
*/
return (self);
}
static int
tdq_pickpri(struct tdq *tdq, struct td_sched *ts, int flags)
{
struct pcpu *pcpu;
int lowpri;
int lowcpu;
int lowload;
int load;
int self;
int pri;
int cpu;
self = PCPU_GET(cpuid);
if (smp_started == 0)
return (self);
pri = ts->ts_thread->td_priority;
/*
* Regardless of affinity, if the last cpu is idle send it there.
*/
pcpu = pcpu_find(ts->ts_cpu);
if (pcpu->pc_curthread->td_priority > PRI_MIN_IDLE) {
CTR5(KTR_ULE,
"ts_cpu %d idle, ltick %d ticks %d pri %d curthread %d",
ts->ts_cpu, ts->ts_rltick, ticks, pri,
pcpu->pc_curthread->td_priority);
return (ts->ts_cpu);
}
/*
* If we have affinity, try to place it on the cpu we last ran on.
*/
if (SCHED_AFFINITY(ts) && pcpu->pc_curthread->td_priority > pri) {
CTR5(KTR_ULE,
"affinity for %d, ltick %d ticks %d pri %d curthread %d",
ts->ts_cpu, ts->ts_rltick, ticks, pri,
pcpu->pc_curthread->td_priority);
return (ts->ts_cpu);
}
/*
* Try ourself first; If we're running something lower priority this
* may have some locality with the waking thread and execute faster
* here.
*/
if (tryself) {
/*
* If we're being awoken by an interrupt thread or the waker
* is going right to sleep run here as well.
*/
if ((TDQ_SELF()->tdq_load == 1) && (flags & SRQ_YIELDING ||
curthread->td_pri_class == PRI_ITHD)) {
CTR2(KTR_ULE, "tryself load %d flags %d",
TDQ_SELF()->tdq_load, flags);
return (self);
}
}
/*
* Look for an idle group.
*/
CTR1(KTR_ULE, "tdq_idle %X", tdq_idle);
cpu = ffs(tdq_idle);
if (cpu)
return (cpu - 1);
if (tryselfidle && pri < curthread->td_priority) {
CTR1(KTR_ULE, "tryself %d",
curthread->td_priority);
return (self);
}
/*
* Now search for the cpu running the lowest priority thread with
* the least load.
*/
lowload = 0;
lowpri = lowcpu = 0;
for (cpu = 0; cpu <= mp_maxid; cpu++) {
if (CPU_ABSENT(cpu))
continue;
pcpu = pcpu_find(cpu);
pri = pcpu->pc_curthread->td_priority;
CTR4(KTR_ULE,
"cpu %d pri %d lowcpu %d lowpri %d",
cpu, pri, lowcpu, lowpri);
if (pri < lowpri)
continue;
load = TDQ_CPU(cpu)->tdq_load;
if (lowpri && lowpri == pri && load > lowload)
continue;
lowpri = pri;
lowcpu = cpu;
lowload = load;
}
return (lowcpu);
}
#endif /* SMP */
/*
* Pick the highest priority task we have and return it.
*/
static struct td_sched *
tdq_choose(struct tdq *tdq)
{
struct td_sched *ts;
mtx_assert(&sched_lock, MA_OWNED);
ts = runq_choose(&tdq->tdq_realtime);
if (ts != NULL)
return (ts);
ts = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
if (ts != NULL) {
KASSERT(ts->ts_thread->td_priority >= PRI_MIN_TIMESHARE,
("tdq_choose: Invalid priority on timeshare queue %d",
ts->ts_thread->td_priority));
return (ts);
}
ts = runq_choose(&tdq->tdq_idle);
if (ts != NULL) {
KASSERT(ts->ts_thread->td_priority >= PRI_MIN_IDLE,
("tdq_choose: Invalid priority on idle queue %d",
ts->ts_thread->td_priority));
return (ts);
}
return (NULL);
}
static void
tdq_setup(struct tdq *tdq)
{
runq_init(&tdq->tdq_realtime);
runq_init(&tdq->tdq_timeshare);
runq_init(&tdq->tdq_idle);
tdq->tdq_load = 0;
}
static void
sched_setup(void *dummy)
{
#ifdef SMP
int i;
#endif
/*
* To avoid divide-by-zero, we set realstathz a dummy value
* in case which sched_clock() called before sched_initticks().
*/
realstathz = hz;
sched_slice = (realstathz/10); /* ~100ms */
tickincr = 1 << SCHED_TICK_SHIFT;
#ifdef SMP
balance_groups = 0;
/*
* Initialize the tdqs.
*/
for (i = 0; i < MAXCPU; i++) {
struct tdq *tdq;
tdq = &tdq_cpu[i];
tdq_setup(&tdq_cpu[i]);
}
if (smp_topology == NULL) {
struct tdq_group *tdg;
struct tdq *tdq;
int cpus;
for (cpus = 0, i = 0; i < MAXCPU; i++) {
if (CPU_ABSENT(i))
continue;
tdq = &tdq_cpu[i];
tdg = &tdq_groups[cpus];
/*
* Setup a tdq group with one member.
*/
tdq->tdq_transferable = 0;
tdq->tdq_group = tdg;
tdg->tdg_cpus = 1;
tdg->tdg_idlemask = 0;
tdg->tdg_cpumask = tdg->tdg_mask = 1 << i;
tdg->tdg_load = 0;
tdg->tdg_transferable = 0;
LIST_INIT(&tdg->tdg_members);
LIST_INSERT_HEAD(&tdg->tdg_members, tdq, tdq_siblings);
cpus++;
}
tdg_maxid = cpus - 1;
} else {
struct tdq_group *tdg;
struct cpu_group *cg;
int j;
topology = 1;
for (i = 0; i < smp_topology->ct_count; i++) {
cg = &smp_topology->ct_group[i];
tdg = &tdq_groups[i];
/*
* Initialize the group.
*/
tdg->tdg_idlemask = 0;
tdg->tdg_load = 0;
tdg->tdg_transferable = 0;
tdg->tdg_cpus = cg->cg_count;
tdg->tdg_cpumask = cg->cg_mask;
LIST_INIT(&tdg->tdg_members);
/*
* Find all of the group members and add them.
*/
for (j = 0; j < MAXCPU; j++) {
if ((cg->cg_mask & (1 << j)) != 0) {
if (tdg->tdg_mask == 0)
tdg->tdg_mask = 1 << j;
tdq_cpu[j].tdq_transferable = 0;
tdq_cpu[j].tdq_group = tdg;
LIST_INSERT_HEAD(&tdg->tdg_members,
&tdq_cpu[j], tdq_siblings);
}
}
if (tdg->tdg_cpus > 1)
balance_groups = 1;
}
tdg_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
tdq_setup(TDQ_SELF());
#endif
mtx_lock_spin(&sched_lock);
tdq_load_add(TDQ_SELF(), &td_sched0);
mtx_unlock_spin(&sched_lock);
}
/* ARGSUSED */
static void
sched_initticks(void *dummy)
{
mtx_lock_spin(&sched_lock);
realstathz = stathz ? stathz : hz;
sched_slice = (realstathz/10); /* ~100ms */
/*
* tickincr is shifted out by 10 to avoid rounding errors due to
* hz not being evenly divisible by stathz on all platforms.
*/
tickincr = (hz << SCHED_TICK_SHIFT) / realstathz;
/*
* This does not work for values of stathz that are more than
* 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
*/
if (tickincr == 0)
tickincr = 1;
#ifdef SMP
affinity = SCHED_AFFINITY_DEFAULT;
#endif
mtx_unlock_spin(&sched_lock);
}
/*
* Scale the scheduling priority according to the "interactivity" of this
* process.
*/
static void
sched_priority(struct thread *td)
{
int score;
int pri;
if (td->td_pri_class != PRI_TIMESHARE)
return;
/*
* If the score is interactive we place the thread in the realtime
* queue with a priority that is less than kernel and interrupt
* priorities. These threads are not subject to nice restrictions.
*
* Scores greater than this are placed on the normal realtime queue
* where the priority is partially decided by the most recent cpu
* utilization and the rest is decided by nice value.
*/
score = sched_interact_score(td);
if (score < sched_interact) {
pri = PRI_MIN_REALTIME;
pri += ((PRI_MAX_REALTIME - PRI_MIN_REALTIME) / sched_interact)
* score;
KASSERT(pri >= PRI_MIN_REALTIME && pri <= PRI_MAX_REALTIME,
("sched_priority: invalid interactive priority %d score %d",
pri, score));
} else {
pri = SCHED_PRI_MIN;
if (td->td_sched->ts_ticks)
pri += SCHED_PRI_TICKS(td->td_sched);
pri += SCHED_PRI_NICE(td->td_proc->p_nice);
if (!(pri >= PRI_MIN_TIMESHARE && pri <= PRI_MAX_TIMESHARE)) {
static int once = 1;
if (once) {
printf("sched_priority: invalid priority %d",
pri);
printf("nice %d, ticks %d ftick %d ltick %d tick pri %d\n",
td->td_proc->p_nice,
td->td_sched->ts_ticks,
td->td_sched->ts_ftick,
td->td_sched->ts_ltick,
SCHED_PRI_TICKS(td->td_sched));
once = 0;
}
pri = min(max(pri, PRI_MIN_TIMESHARE),
PRI_MAX_TIMESHARE);
}
}
sched_user_prio(td, pri);
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.
*/
static void
sched_interact_update(struct thread *td)
{
struct td_sched *ts;
u_int sum;
ts = td->td_sched;
sum = ts->skg_runtime + ts->skg_slptime;
if (sum < SCHED_SLP_RUN_MAX)
return;
/*
* This only happens from two places:
* 1) We have added an unusual amount of run time from fork_exit.
* 2) We have added an unusual amount of sleep time from sched_sleep().
*/
if (sum > SCHED_SLP_RUN_MAX * 2) {
if (ts->skg_runtime > ts->skg_slptime) {
ts->skg_runtime = SCHED_SLP_RUN_MAX;
ts->skg_slptime = 1;
} else {
ts->skg_slptime = SCHED_SLP_RUN_MAX;
ts->skg_runtime = 1;
}
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) {
ts->skg_runtime /= 2;
ts->skg_slptime /= 2;
return;
}
ts->skg_runtime = (ts->skg_runtime / 5) * 4;
ts->skg_slptime = (ts->skg_slptime / 5) * 4;
}
static void
sched_interact_fork(struct thread *td)
{
int ratio;
int sum;
sum = td->td_sched->skg_runtime + td->td_sched->skg_slptime;
if (sum > SCHED_SLP_RUN_FORK) {
ratio = sum / SCHED_SLP_RUN_FORK;
td->td_sched->skg_runtime /= ratio;
td->td_sched->skg_slptime /= ratio;
}
}
static int
sched_interact_score(struct thread *td)
{
int div;
if (td->td_sched->skg_runtime > td->td_sched->skg_slptime) {
div = max(1, td->td_sched->skg_runtime / SCHED_INTERACT_HALF);
return (SCHED_INTERACT_HALF +
(SCHED_INTERACT_HALF - (td->td_sched->skg_slptime / div)));
}
if (td->td_sched->skg_slptime > td->td_sched->skg_runtime) {
div = max(1, td->td_sched->skg_slptime / SCHED_INTERACT_HALF);
return (td->td_sched->skg_runtime / div);
}
/* runtime == slptime */
if (td->td_sched->skg_runtime)
return (SCHED_INTERACT_HALF);
/*
* This can happen if slptime and runtime are 0.
*/
return (0);
}
/*
* Called from proc0_init() to bootstrap the scheduler.
*/
void
schedinit(void)
{
/*
* Set up the scheduler specific parts of proc0.
*/
proc0.p_sched = NULL; /* XXX */
thread0.td_sched = &td_sched0;
thread0.td_lock = &sched_lock;
td_sched0.ts_ltick = ticks;
td_sched0.ts_ftick = ticks;
td_sched0.ts_thread = &thread0;
}
/*
* 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 stathz ticks.
*/
int
sched_rr_interval(void)
{
/* Convert sched_slice to hz */
return (hz/(realstathz/sched_slice));
}
static void
sched_pctcpu_update(struct td_sched *ts)
{
if (ts->ts_ticks == 0)
return;
if (ticks - (hz / 10) < ts->ts_ltick &&
SCHED_TICK_TOTAL(ts) < SCHED_TICK_MAX)
return;
/*
* Adjust counters and watermark for pctcpu calc.
*/
if (ts->ts_ltick > ticks - SCHED_TICK_TARG)
ts->ts_ticks = (ts->ts_ticks / (ticks - ts->ts_ftick)) *
SCHED_TICK_TARG;
else
ts->ts_ticks = 0;
ts->ts_ltick = ticks;
ts->ts_ftick = ts->ts_ltick - SCHED_TICK_TARG;
}
static void
sched_thread_priority(struct thread *td, u_char prio)
{
struct td_sched *ts;
CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)",
td, td->td_proc->p_comm, td->td_priority, prio, curthread,
curthread->td_proc->p_comm);
ts = td->td_sched;
THREAD_LOCK_ASSERT(td, MA_OWNED);
if (td->td_priority == prio)
return;
if (TD_ON_RUNQ(td) && prio < td->td_priority) {
/*
* If the priority has been elevated due to priority
* propagation, we may have to move ourselves to a new
* queue. This could be optimized to not re-add in some
* cases.
*/
MPASS(td->td_lock == &sched_lock);
sched_rem(td);
td->td_priority = prio;
sched_add(td, SRQ_BORROWING|SRQ_OURSELF);
} else
td->td_priority = prio;
}
/*
* Update a thread's priority when it is lent another thread's
* priority.
*/
void
sched_lend_prio(struct thread *td, u_char prio)
{
td->td_flags |= TDF_BORROWING;
sched_thread_priority(td, prio);
}
/*
* Restore a thread's priority when priority propagation is
* over. The prio argument is the minimum priority the thread
* needs to have to satisfy other possible priority lending
* requests. If the thread's regular priority is less
* important than prio, the thread will keep a priority boost
* of prio.
*/
void
sched_unlend_prio(struct thread *td, u_char prio)
{
u_char base_pri;
if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
td->td_base_pri <= PRI_MAX_TIMESHARE)
base_pri = td->td_user_pri;
else
base_pri = td->td_base_pri;
if (prio >= base_pri) {
td->td_flags &= ~TDF_BORROWING;
sched_thread_priority(td, base_pri);
} else
sched_lend_prio(td, prio);
}
void
sched_prio(struct thread *td, u_char prio)
{
u_char oldprio;
/* First, update the base priority. */
td->td_base_pri = prio;
/*
* If the thread is borrowing another thread's priority, don't
* ever lower the priority.
*/
if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
return;
/* Change the real priority. */
oldprio = td->td_priority;
sched_thread_priority(td, prio);
/*
* If the thread is on a turnstile, then let the turnstile update
* its state.
*/
if (TD_ON_LOCK(td) && oldprio != prio)
turnstile_adjust(td, oldprio);
}
void
sched_user_prio(struct thread *td, u_char prio)
{
u_char oldprio;
td->td_base_user_pri = prio;
if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio)
return;
oldprio = td->td_user_pri;
td->td_user_pri = prio;
if (TD_ON_UPILOCK(td) && oldprio != prio)
umtx_pi_adjust(td, oldprio);
}
void
sched_lend_user_prio(struct thread *td, u_char prio)
{
u_char oldprio;
td->td_flags |= TDF_UBORROWING;
oldprio = td->td_user_pri;
td->td_user_pri = prio;
if (TD_ON_UPILOCK(td) && oldprio != prio)
umtx_pi_adjust(td, oldprio);
}
void
sched_unlend_user_prio(struct thread *td, u_char prio)
{
u_char base_pri;
base_pri = td->td_base_user_pri;
if (prio >= base_pri) {
td->td_flags &= ~TDF_UBORROWING;
sched_user_prio(td, base_pri);
} else
sched_lend_user_prio(td, prio);
}
void
sched_switch(struct thread *td, struct thread *newtd, int flags)
{
struct tdq *tdq;
struct td_sched *ts;
int preempt;
THREAD_LOCK_ASSERT(td, MA_OWNED);
preempt = flags & SW_PREEMPT;
tdq = TDQ_SELF();
ts = td->td_sched;
td->td_lastcpu = td->td_oncpu;
td->td_oncpu = NOCPU;
td->td_flags &= ~TDF_NEEDRESCHED;
td->td_owepreempt = 0;
/*
* If the thread has been assigned it may be in the process of switching
* to the new cpu. This is the case in sched_bind().
*/
/*
* Switch to the sched lock to fix things up and pick
* a new thread.
*/
if (td->td_lock != &sched_lock) {
mtx_lock_spin(&sched_lock);
thread_unlock(td);
}
if (TD_IS_IDLETHREAD(td)) {
MPASS(td->td_lock == &sched_lock);
TD_SET_CAN_RUN(td);
} else if (TD_IS_RUNNING(td)) {
/*
* Don't allow the thread to migrate
* from a preemption.
*/
tdq_load_rem(tdq, ts);
if (preempt)
sched_pin_td(td);
sched_add(td, preempt ?
SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
SRQ_OURSELF|SRQ_YIELDING);
if (preempt)
sched_unpin_td(td);
} else
tdq_load_rem(tdq, ts);
mtx_assert(&sched_lock, MA_OWNED);
if (newtd != NULL) {
/*
* If we bring in a thread account for it as if it had been
* added to the run queue and then chosen.
*/
TD_SET_RUNNING(newtd);
tdq_load_add(TDQ_SELF(), newtd->td_sched);
} else
newtd = choosethread();
if (td != newtd) {
#ifdef HWPMC_HOOKS
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
#endif
cpu_switch(td, newtd, td->td_lock);
#ifdef HWPMC_HOOKS
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
#endif
}
sched_lock.mtx_lock = (uintptr_t)td;
td->td_oncpu = PCPU_GET(cpuid);
MPASS(td->td_lock == &sched_lock);
}
void
sched_nice(struct proc *p, int nice)
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK_ASSERT(p, MA_OWNED);
p->p_nice = nice;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
sched_priority(td);
sched_prio(td, td->td_base_user_pri);
thread_unlock(td);
}
}
void
sched_sleep(struct thread *td)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_sched->ts_slptime = ticks;
}
void
sched_wakeup(struct thread *td)
{
struct td_sched *ts;
int slptime;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td->td_sched;
/*
* If we slept for more than a tick update our interactivity and
* priority.
*/
slptime = ts->ts_slptime;
ts->ts_slptime = 0;
if (slptime && slptime != ticks) {
u_int hzticks;
hzticks = (ticks - slptime) << SCHED_TICK_SHIFT;
ts->skg_slptime += hzticks;
sched_interact_update(td);
sched_pctcpu_update(ts);
sched_priority(td);
}
/* Reset the slice value after we sleep. */
ts->ts_slice = sched_slice;
sched_add(td, SRQ_BORING);
}
/*
* Penalize the parent for creating a new child and initialize the child's
* priority.
*/
void
sched_fork(struct thread *td, struct thread *child)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
sched_fork_thread(td, child);
/*
* Penalize the parent and child for forking.
*/
sched_interact_fork(child);
sched_priority(child);
td->td_sched->skg_runtime += tickincr;
sched_interact_update(td);
sched_priority(td);
}
void
sched_fork_thread(struct thread *td, struct thread *child)
{
struct td_sched *ts;
struct td_sched *ts2;
/*
* Initialize child.
*/
THREAD_LOCK_ASSERT(td, MA_OWNED);
sched_newthread(child);
child->td_lock = &sched_lock;
ts = td->td_sched;
ts2 = child->td_sched;
ts2->ts_cpu = ts->ts_cpu;
ts2->ts_runq = NULL;
/*
* Grab our parents cpu estimation information and priority.
*/
ts2->ts_ticks = ts->ts_ticks;
ts2->ts_ltick = ts->ts_ltick;
ts2->ts_ftick = ts->ts_ftick;
child->td_user_pri = td->td_user_pri;
child->td_base_user_pri = td->td_base_user_pri;
/*
* And update interactivity score.
*/
ts2->skg_slptime = ts->skg_slptime;
ts2->skg_runtime = ts->skg_runtime;
ts2->ts_slice = 1; /* Attempt to quickly learn interactivity. */
}
void
sched_class(struct thread *td, int class)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
if (td->td_pri_class == class)
return;
#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 (TD_ON_RUNQ(td)) {
struct tdq *tdq;
tdq = TDQ_CPU(td->td_sched->ts_cpu);
if (THREAD_CAN_MIGRATE(td)) {
tdq->tdq_transferable--;
tdq->tdq_group->tdg_transferable--;
}
td->td_pri_class = class;
if (THREAD_CAN_MIGRATE(td)) {
tdq->tdq_transferable++;
tdq->tdq_group->tdg_transferable++;
}
}
#endif
td->td_pri_class = class;
}
/*
* Return some of the child's priority and interactivity to the parent.
*/
void
sched_exit(struct proc *p, struct thread *child)
{
struct thread *td;
CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d",
child, child->td_proc->p_comm, child->td_priority);
PROC_SLOCK_ASSERT(p, MA_OWNED);
td = FIRST_THREAD_IN_PROC(p);
sched_exit_thread(td, child);
}
void
sched_exit_thread(struct thread *td, struct thread *child)
{
CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d",
child, child->td_proc->p_comm, child->td_priority);
thread_lock(child);
tdq_load_rem(TDQ_CPU(child->td_sched->ts_cpu), child->td_sched);
thread_unlock(child);
#ifdef KSE
/*
* KSE forks and exits so often that this penalty causes short-lived
* threads to always be non-interactive. This causes mozilla to
* crawl under load.
*/
if ((td->td_pflags & TDP_SA) && td->td_proc == child->td_proc)
return;
#endif
/*
* Give the child's runtime to the parent without returning the
* sleep time as a penalty to the parent. This causes shells that
* launch expensive things to mark their children as expensive.
*/
thread_lock(td);
td->td_sched->skg_runtime += child->td_sched->skg_runtime;
sched_interact_update(td);
sched_priority(td);
thread_unlock(td);
}
void
sched_userret(struct thread *td)
{
/*
* XXX we cheat slightly on the locking here to avoid locking in
* the usual case. Setting td_priority here is essentially an
* incomplete workaround for not setting it properly elsewhere.
* Now that some interrupt handlers are threads, not setting it
* properly elsewhere can clobber it in the window between setting
* it here and returning to user mode, so don't waste time setting
* it perfectly here.
*/
KASSERT((td->td_flags & TDF_BORROWING) == 0,
("thread with borrowed priority returning to userland"));
if (td->td_priority != td->td_user_pri) {
thread_lock(td);
td->td_priority = td->td_user_pri;
td->td_base_pri = td->td_user_pri;
thread_unlock(td);
}
}
void
sched_clock(struct thread *td)
{
struct tdq *tdq;
struct td_sched *ts;
mtx_assert(&sched_lock, MA_OWNED);
#ifdef SMP
sched_smp_tick(td);
#endif
tdq = TDQ_SELF();
/*
* Advance the insert index once for each tick to ensure that all
* threads get a chance to run.
*/
if (tdq->tdq_idx == tdq->tdq_ridx) {
tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
tdq->tdq_ridx = tdq->tdq_idx;
}
ts = td->td_sched;
/*
* We only do slicing code for TIMESHARE threads.
*/
if (td->td_pri_class != PRI_TIMESHARE)
return;
/*
* We used a tick; charge it to the thread so that we can compute our
* interactivity.
*/
td->td_sched->skg_runtime += tickincr;
sched_interact_update(td);
/*
* We used up one time slice.
*/
if (--ts->ts_slice > 0)
return;
/*
* We're out of time, recompute priorities and requeue.
*/
sched_priority(td);
td->td_flags |= TDF_NEEDRESCHED;
}
int
sched_runnable(void)
{
struct tdq *tdq;
int load;
load = 1;
tdq = TDQ_SELF();
#ifdef SMP
if (tdq_busy)
goto out;
#endif
if ((curthread->td_flags & TDF_IDLETD) != 0) {
if (tdq->tdq_load > 0)
goto out;
} else
if (tdq->tdq_load - 1 > 0)
goto out;
load = 0;
out:
return (load);
}
struct thread *
sched_choose(void)
{
struct tdq *tdq;
struct td_sched *ts;
mtx_assert(&sched_lock, MA_OWNED);
tdq = TDQ_SELF();
#ifdef SMP
restart:
#endif
ts = tdq_choose(tdq);
if (ts) {
#ifdef SMP
if (ts->ts_thread->td_priority > PRI_MIN_IDLE)
if (tdq_idled(tdq) == 0)
goto restart;
#endif
tdq_runq_rem(tdq, ts);
return (ts->ts_thread);
}
#ifdef SMP
if (tdq_idled(tdq) == 0)
goto restart;
#endif
return (PCPU_GET(idlethread));
}
static int
sched_preempt(struct thread *td)
{
struct thread *ctd;
int cpri;
int pri;
ctd = curthread;
pri = td->td_priority;
cpri = ctd->td_priority;
if (panicstr != NULL || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
return (0);
/*
* Always preempt IDLE threads. Otherwise only if the preempting
* thread is an ithread.
*/
if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE)
return (0);
if (ctd->td_critnest > 1) {
CTR1(KTR_PROC, "sched_preempt: in critical section %d",
ctd->td_critnest);
ctd->td_owepreempt = 1;
return (0);
}
/*
* Thread is runnable but not yet put on system run queue.
*/
MPASS(TD_ON_RUNQ(td));
TD_SET_RUNNING(td);
MPASS(ctd->td_lock == &sched_lock);
MPASS(td->td_lock == &sched_lock);
CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td,
td->td_proc->p_pid, td->td_proc->p_comm);
/*
* We enter the switch with two runnable threads that both have
* the same lock. When we return td may be sleeping so we need
* to switch locks to make sure he's locked correctly.
*/
SCHED_STAT_INC(switch_preempt);
mi_switch(SW_INVOL|SW_PREEMPT, td);
spinlock_enter();
thread_unlock(ctd);
thread_lock(td);
spinlock_exit();
return (1);
}
void
sched_add(struct thread *td, int flags)
{
struct tdq *tdq;
struct td_sched *ts;
int preemptive;
int class;
#ifdef SMP
int cpuid;
int cpumask;
#endif
ts = td->td_sched;
THREAD_LOCK_ASSERT(td, MA_OWNED);
CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)",
td, td->td_proc->p_comm, td->td_priority, curthread,
curthread->td_proc->p_comm);
KASSERT((td->td_inhibitors == 0),
("sched_add: trying to run inhibited thread"));
KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
("sched_add: bad thread state"));
KASSERT(td->td_proc->p_sflag & PS_INMEM,
("sched_add: process swapped out"));
/*
* Now that the thread is moving to the run-queue, set the lock
* to the scheduler's lock.
*/
if (td->td_lock != &sched_lock) {
mtx_lock_spin(&sched_lock);
thread_lock_set(td, &sched_lock);
}
mtx_assert(&sched_lock, MA_OWNED);
TD_SET_RUNQ(td);
tdq = TDQ_SELF();
class = PRI_BASE(td->td_pri_class);
preemptive = !(flags & SRQ_YIELDING);
/*
* Recalculate the priority before we select the target cpu or
* run-queue.
*/
if (class == PRI_TIMESHARE)
sched_priority(td);
if (ts->ts_slice == 0)
ts->ts_slice = sched_slice;
#ifdef SMP
cpuid = PCPU_GET(cpuid);
/*
* Pick the destination cpu and if it isn't ours transfer to the
* target cpu.
*/
if (THREAD_CAN_MIGRATE(td)) {
if (td->td_priority <= PRI_MAX_ITHD) {
CTR2(KTR_ULE, "ithd %d < %d",
td->td_priority, PRI_MAX_ITHD);
ts->ts_cpu = cpuid;
} else if (pick_pri)
ts->ts_cpu = tdq_pickpri(tdq, ts, flags);
else
ts->ts_cpu = tdq_pickidle(tdq, ts);
} else
CTR1(KTR_ULE, "pinned %d", td->td_pinned);
if (ts->ts_cpu != cpuid)
preemptive = 0;
tdq = TDQ_CPU(ts->ts_cpu);
cpumask = 1 << ts->ts_cpu;
/*
* If we had been idle, clear our bit in the group and potentially
* the global bitmap.
*/
if ((class != PRI_IDLE && class != PRI_ITHD) &&
(tdq->tdq_group->tdg_idlemask & cpumask) != 0) {
/*
* Check to see if our group is unidling, and if so, remove it
* from the global idle mask.
*/
if (tdq->tdq_group->tdg_idlemask ==
tdq->tdq_group->tdg_cpumask)
atomic_clear_int(&tdq_idle, tdq->tdq_group->tdg_mask);
/*
* Now remove ourselves from the group specific idle mask.
*/
tdq->tdq_group->tdg_idlemask &= ~cpumask;
}
#endif
/*
* Pick the run queue based on priority.
*/
if (td->td_priority <= PRI_MAX_REALTIME)
ts->ts_runq = &tdq->tdq_realtime;
else if (td->td_priority <= PRI_MAX_TIMESHARE)
ts->ts_runq = &tdq->tdq_timeshare;
else
ts->ts_runq = &tdq->tdq_idle;
if (preemptive && sched_preempt(td))
return;
tdq_runq_add(tdq, ts, flags);
tdq_load_add(tdq, ts);
#ifdef SMP
if (ts->ts_cpu != cpuid) {
tdq_notify(ts);
return;
}
#endif
if (td->td_priority < curthread->td_priority)
curthread->td_flags |= TDF_NEEDRESCHED;
}
void
sched_rem(struct thread *td)
{
struct tdq *tdq;
struct td_sched *ts;
CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)",
td, td->td_proc->p_comm, td->td_priority, curthread,
curthread->td_proc->p_comm);
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td->td_sched;
KASSERT(TD_ON_RUNQ(td),
("sched_rem: thread not on run queue"));
tdq = TDQ_CPU(ts->ts_cpu);
tdq_runq_rem(tdq, ts);
tdq_load_rem(tdq, ts);
TD_SET_CAN_RUN(td);
}
fixpt_t
sched_pctcpu(struct thread *td)
{
fixpt_t pctcpu;
struct td_sched *ts;
pctcpu = 0;
ts = td->td_sched;
if (ts == NULL)
return (0);
thread_lock(td);
if (ts->ts_ticks) {
int rtick;
sched_pctcpu_update(ts);
/* How many rtick per second ? */
rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
}
td->td_proc->p_swtime = ts->ts_ltick - ts->ts_ftick;
thread_unlock(td);
return (pctcpu);
}
void
sched_bind(struct thread *td, int cpu)
{
struct td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td->td_sched;
if (ts->ts_flags & TSF_BOUND)
sched_unbind(td);
ts->ts_flags |= TSF_BOUND;
#ifdef SMP
sched_pin();
if (PCPU_GET(cpuid) == cpu)
return;
ts->ts_cpu = 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)
{
struct td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td->td_sched;
if ((ts->ts_flags & TSF_BOUND) == 0)
return;
ts->ts_flags &= ~TSF_BOUND;
#ifdef SMP
sched_unpin();
#endif
}
int
sched_is_bound(struct thread *td)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
return (td->td_sched->ts_flags & TSF_BOUND);
}
void
sched_relinquish(struct thread *td)
{
thread_lock(td);
if (td->td_pri_class == PRI_TIMESHARE)
sched_prio(td, PRI_MAX_TIMESHARE);
SCHED_STAT_INC(switch_relinquish);
mi_switch(SW_VOL, NULL);
thread_unlock(td);
}
int
sched_load(void)
{
#ifdef SMP
int total;
int i;
total = 0;
for (i = 0; i <= tdg_maxid; i++)
total += TDQ_GROUP(i)->tdg_load;
return (total);
#else
return (TDQ_SELF()->tdq_sysload);
#endif
}
int
sched_sizeof_proc(void)
{
return (sizeof(struct proc));
}
int
sched_sizeof_thread(void)
{
return (sizeof(struct thread) + sizeof(struct td_sched));
}
void
sched_tick(void)
{
struct td_sched *ts;
ts = curthread->td_sched;
/* Adjust ticks for pctcpu */
ts->ts_ticks += 1 << SCHED_TICK_SHIFT;
ts->ts_ltick = ticks;
/*
* Update if we've exceeded our desired tick threshhold by over one
* second.
*/
if (ts->ts_ftick + SCHED_TICK_MAX < ts->ts_ltick)
sched_pctcpu_update(ts);
}
/*
* The actual idle process.
*/
void
sched_idletd(void *dummy)
{
struct proc *p;
struct thread *td;
td = curthread;
p = td->td_proc;
mtx_assert(&Giant, MA_NOTOWNED);
/* ULE Relies on preemption for idle interruption. */
for (;;)
cpu_idle();
}
/*
* A CPU is entering for the first time or a thread is exiting.
*/
void
sched_throw(struct thread *td)
{
/*
* Correct spinlock nesting. The idle thread context that we are
* borrowing was created so that it would start out with a single
* spin lock (sched_lock) held in fork_trampoline(). Since we've
* explicitly acquired locks in this function, the nesting count
* is now 2 rather than 1. Since we are nested, calling
* spinlock_exit() will simply adjust the counts without allowing
* spin lock using code to interrupt us.
*/
if (td == NULL) {
mtx_lock_spin(&sched_lock);
spinlock_exit();
} else {
MPASS(td->td_lock == &sched_lock);
}
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
PCPU_SET(switchtime, cpu_ticks());
PCPU_SET(switchticks, ticks);
cpu_throw(td, choosethread()); /* doesn't return */
}
void
sched_fork_exit(struct thread *td)
{
/*
* Finish setting up thread glue so that it begins execution in a
* non-nested critical section with sched_lock held but not recursed.
*/
td->td_oncpu = PCPU_GET(cpuid);
sched_lock.mtx_lock = (uintptr_t)td;
THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
}
static SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler");
SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ule", 0,
"Scheduler name");
SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, tickincr, CTLFLAG_RD, &tickincr, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, realstathz, CTLFLAG_RD, &realstathz, 0, "");
#ifdef SMP
SYSCTL_INT(_kern_sched, OID_AUTO, pick_pri, CTLFLAG_RW, &pick_pri, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, pick_pri_affinity, CTLFLAG_RW,
&affinity, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, pick_pri_tryself, CTLFLAG_RW,
&tryself, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, pick_pri_tryselfidle, CTLFLAG_RW,
&tryselfidle, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, ipi_preempt, CTLFLAG_RW, &ipi_preempt, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, ipi_ast, CTLFLAG_RW, &ipi_ast, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, ipi_thresh, CTLFLAG_RW, &ipi_thresh, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, steal_htt, CTLFLAG_RW, &steal_htt, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, steal_busy, CTLFLAG_RW, &steal_busy, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, busy_thresh, CTLFLAG_RW, &busy_thresh, 0, "");
SYSCTL_INT(_kern_sched, OID_AUTO, topology, CTLFLAG_RD, &topology, 0, "");
#endif
/* ps compat */
static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
#define KERN_SWITCH_INCLUDE 1
#include "kern/kern_switch.c"
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