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freebsd-skq/sys/kern/sched_4bsd.c

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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1982, 1986, 1990, 1991, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* 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, 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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/cpuset.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/kthread.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/turnstile.h>
#include <sys/umtx.h>
#include <machine/pcb.h>
#include <machine/smp.h>
#ifdef HWPMC_HOOKS
#include <sys/pmckern.h>
#endif
#ifdef KDTRACE_HOOKS
#include <sys/dtrace_bsd.h>
int __read_mostly dtrace_vtime_active;
dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
#endif
/*
* INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in
* the range 100-256 Hz (approximately).
*/
#define ESTCPULIM(e) \
min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \
RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1)
#ifdef SMP
#define INVERSE_ESTCPU_WEIGHT (8 * smp_cpus)
#else
#define INVERSE_ESTCPU_WEIGHT 8 /* 1 / (priorities per estcpu level). */
#endif
#define NICE_WEIGHT 1 /* Priorities per nice level. */
#define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
/*
* The schedulable entity that runs a context.
* This is an extension to the thread structure and is tailored to
* the requirements of this scheduler.
* All fields are protected by the scheduler lock.
*/
struct td_sched {
fixpt_t ts_pctcpu; /* %cpu during p_swtime. */
u_int ts_estcpu; /* Estimated cpu utilization. */
int ts_cpticks; /* Ticks of cpu time. */
int ts_slptime; /* Seconds !RUNNING. */
int ts_slice; /* Remaining part of time slice. */
int ts_flags;
struct runq *ts_runq; /* runq the thread is currently on */
#ifdef KTR
char ts_name[TS_NAME_LEN];
#endif
};
/* flags kept in td_flags */
#define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */
#define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */
#define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
/* flags kept in ts_flags */
#define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */
#define SKE_RUNQ_PCPU(ts) \
((ts)->ts_runq != 0 && (ts)->ts_runq != &runq)
#define THREAD_CAN_SCHED(td, cpu) \
CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
_Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <=
sizeof(struct thread0_storage),
"increase struct thread0_storage.t0st_sched size");
static struct mtx sched_lock;
static int realstathz = 127; /* stathz is sometimes 0 and run off of hz. */
static int sched_tdcnt; /* Total runnable threads in the system. */
static int sched_slice = 12; /* Thread run time before rescheduling. */
static void setup_runqs(void);
static void schedcpu(void);
static void schedcpu_thread(void);
static void sched_priority(struct thread *td, u_char prio);
static void sched_setup(void *dummy);
static void maybe_resched(struct thread *td);
static void updatepri(struct thread *td);
static void resetpriority(struct thread *td);
static void resetpriority_thread(struct thread *td);
#ifdef SMP
static int sched_pickcpu(struct thread *td);
static int forward_wakeup(int cpunum);
static void kick_other_cpu(int pri, int cpuid);
#endif
static struct kproc_desc sched_kp = {
"schedcpu",
schedcpu_thread,
NULL
};
SYSINIT(schedcpu, SI_SUB_LAST, SI_ORDER_FIRST, kproc_start,
&sched_kp);
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);
/*
* Global run queue.
*/
static struct runq runq;
#ifdef SMP
/*
* Per-CPU run queues
*/
static struct runq runq_pcpu[MAXCPU];
long runq_length[MAXCPU];
static cpuset_t idle_cpus_mask;
#endif
struct pcpuidlestat {
u_int idlecalls;
u_int oldidlecalls;
};
DPCPU_DEFINE_STATIC(struct pcpuidlestat, idlestat);
static void
setup_runqs(void)
{
#ifdef SMP
int i;
for (i = 0; i < MAXCPU; ++i)
runq_init(&runq_pcpu[i]);
#endif
runq_init(&runq);
}
static int
sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
{
int error, new_val, period;
period = 1000000 / realstathz;
new_val = period * sched_slice;
error = sysctl_handle_int(oidp, &new_val, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
if (new_val <= 0)
return (EINVAL);
sched_slice = imax(1, (new_val + period / 2) / period);
hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
realstathz);
return (0);
}
SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
"Scheduler");
SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0,
"Scheduler name");
SYSCTL_PROC(_kern_sched, OID_AUTO, quantum,
CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
sysctl_kern_quantum, "I",
"Quantum for timeshare threads in microseconds");
SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
"Quantum for timeshare threads in stathz ticks");
#ifdef SMP
/* Enable forwarding of wakeups to all other cpus */
static SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup,
CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
"Kernel SMP");
static int runq_fuzz = 1;
SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, "");
static int forward_wakeup_enabled = 1;
SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW,
&forward_wakeup_enabled, 0,
"Forwarding of wakeup to idle CPUs");
static int forward_wakeups_requested = 0;
SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD,
&forward_wakeups_requested, 0,
"Requests for Forwarding of wakeup to idle CPUs");
static int forward_wakeups_delivered = 0;
SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD,
&forward_wakeups_delivered, 0,
"Completed Forwarding of wakeup to idle CPUs");
static int forward_wakeup_use_mask = 1;
SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW,
&forward_wakeup_use_mask, 0,
"Use the mask of idle cpus");
static int forward_wakeup_use_loop = 0;
SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW,
&forward_wakeup_use_loop, 0,
"Use a loop to find idle cpus");
#endif
#if 0
static int sched_followon = 0;
SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW,
&sched_followon, 0,
"allow threads to share a quantum");
#endif
SDT_PROVIDER_DEFINE(sched);
SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
"struct proc *", "uint8_t");
SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
"struct proc *", "void *");
SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
"struct proc *", "void *", "int");
SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
"struct proc *", "uint8_t", "struct thread *");
SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
"struct proc *");
SDT_PROBE_DEFINE(sched, , , on__cpu);
SDT_PROBE_DEFINE(sched, , , remain__cpu);
SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
"struct proc *");
static __inline void
sched_load_add(void)
{
sched_tdcnt++;
KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt);
}
static __inline void
sched_load_rem(void)
{
sched_tdcnt--;
KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt);
}
/*
* Arrange to reschedule if necessary, taking the priorities and
* schedulers into account.
*/
static void
maybe_resched(struct thread *td)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
if (td->td_priority < curthread->td_priority)
curthread->td_flags |= TDF_NEEDRESCHED;
}
/*
* This function is called when a thread is about to be put on run queue
* because it has been made runnable or its priority has been adjusted. It
* determines if the new thread should preempt the current thread. If so,
* it sets td_owepreempt to request a preemption.
*/
int
maybe_preempt(struct thread *td)
{
#ifdef PREEMPTION
struct thread *ctd;
int cpri, pri;
/*
* The new thread should not preempt the current thread if any of the
* following conditions are true:
*
* - The kernel is in the throes of crashing (panicstr).
* - The current thread has a higher (numerically lower) or
* equivalent priority. Note that this prevents curthread from
* trying to preempt to itself.
* - The current thread has an inhibitor set or is in the process of
* exiting. In this case, the current thread is about to switch
* out anyways, so there's no point in preempting. If we did,
* the current thread would not be properly resumed as well, so
* just avoid that whole landmine.
* - If the new thread's priority is not a realtime priority and
* the current thread's priority is not an idle priority and
* FULL_PREEMPTION is disabled.
*
* If all of these conditions are false, but the current thread is in
* a nested critical section, then we have to defer the preemption
* until we exit the critical section. Otherwise, switch immediately
* to the new thread.
*/
ctd = curthread;
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT((td->td_inhibitors == 0),
("maybe_preempt: trying to run inhibited thread"));
pri = td->td_priority;
cpri = ctd->td_priority;
if (KERNEL_PANICKED() || pri >= cpri /* || dumping */ ||
TD_IS_INHIBITED(ctd))
return (0);
#ifndef FULL_PREEMPTION
if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE)
return (0);
#endif
CTR0(KTR_PROC, "maybe_preempt: scheduling preemption");
ctd->td_owepreempt = 1;
return (1);
#else
return (0);
#endif
}
/*
* Constants for digital decay and forget:
* 90% of (ts_estcpu) usage in 5 * loadav time
* 95% of (ts_pctcpu) usage in 60 seconds (load insensitive)
* Note that, as ps(1) mentions, this can let percentages
* total over 100% (I've seen 137.9% for 3 processes).
*
* Note that schedclock() updates ts_estcpu and p_cpticks asynchronously.
*
* We wish to decay away 90% of ts_estcpu in (5 * loadavg) seconds.
* That is, the system wants to compute a value of decay such
* that the following for loop:
* for (i = 0; i < (5 * loadavg); i++)
* ts_estcpu *= decay;
* will compute
* ts_estcpu *= 0.1;
* for all values of loadavg:
*
* Mathematically this loop can be expressed by saying:
* decay ** (5 * loadavg) ~= .1
*
* The system computes decay as:
* decay = (2 * loadavg) / (2 * loadavg + 1)
*
* We wish to prove that the system's computation of decay
* will always fulfill the equation:
* decay ** (5 * loadavg) ~= .1
*
* If we compute b as:
* b = 2 * loadavg
* then
* decay = b / (b + 1)
*
* We now need to prove two things:
* 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
* 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
*
* Facts:
* For x close to zero, exp(x) =~ 1 + x, since
* exp(x) = 0! + x**1/1! + x**2/2! + ... .
* therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
* For x close to zero, ln(1+x) =~ x, since
* ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
* therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
* ln(.1) =~ -2.30
*
* Proof of (1):
* Solve (factor)**(power) =~ .1 given power (5*loadav):
* solving for factor,
* ln(factor) =~ (-2.30/5*loadav), or
* factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
* exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
*
* Proof of (2):
* Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
* solving for power,
* power*ln(b/(b+1)) =~ -2.30, or
* power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
*
* Actual power values for the implemented algorithm are as follows:
* loadav: 1 2 3 4
* power: 5.68 10.32 14.94 19.55
*/
/* calculations for digital decay to forget 90% of usage in 5*loadav sec */
#define loadfactor(loadav) (2 * (loadav))
#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
/* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
SYSCTL_UINT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0,
"Decay factor used for updating %CPU");
/*
* If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
* faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
* and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
*
* To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
* 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
*
* If you don't want to bother with the faster/more-accurate formula, you
* can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
* (more general) method of calculating the %age of CPU used by a process.
*/
#define CCPU_SHIFT 11
/*
* Recompute process priorities, every hz ticks.
* MP-safe, called without the Giant mutex.
*/
/* ARGSUSED */
static void
schedcpu(void)
{
fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
struct thread *td;
struct proc *p;
struct td_sched *ts;
int awake;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
PROC_LOCK(p);
if (p->p_state == PRS_NEW) {
PROC_UNLOCK(p);
continue;
}
FOREACH_THREAD_IN_PROC(p, td) {
awake = 0;
ts = td_get_sched(td);
thread_lock(td);
/*
* Increment sleep time (if sleeping). We
* ignore overflow, as above.
*/
/*
* The td_sched slptimes are not touched in wakeup
* because the thread may not HAVE everything in
* memory? XXX I think this is out of date.
*/
if (TD_ON_RUNQ(td)) {
awake = 1;
td->td_flags &= ~TDF_DIDRUN;
} else if (TD_IS_RUNNING(td)) {
awake = 1;
/* Do not clear TDF_DIDRUN */
} else if (td->td_flags & TDF_DIDRUN) {
awake = 1;
td->td_flags &= ~TDF_DIDRUN;
}
/*
* ts_pctcpu is only for ps and ttyinfo().
*/
ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT;
/*
* If the td_sched has been idle the entire second,
* stop recalculating its priority until
* it wakes up.
*/
if (ts->ts_cpticks != 0) {
#if (FSHIFT >= CCPU_SHIFT)
ts->ts_pctcpu += (realstathz == 100)
? ((fixpt_t) ts->ts_cpticks) <<
(FSHIFT - CCPU_SHIFT) :
100 * (((fixpt_t) ts->ts_cpticks)
<< (FSHIFT - CCPU_SHIFT)) / realstathz;
#else
ts->ts_pctcpu += ((FSCALE - ccpu) *
(ts->ts_cpticks *
FSCALE / realstathz)) >> FSHIFT;
#endif
ts->ts_cpticks = 0;
}
/*
* If there are ANY running threads in this process,
* then don't count it as sleeping.
* XXX: this is broken.
*/
if (awake) {
if (ts->ts_slptime > 1) {
/*
* In an ideal world, this should not
* happen, because whoever woke us
* up from the long sleep should have
* unwound the slptime and reset our
* priority before we run at the stale
* priority. Should KASSERT at some
* point when all the cases are fixed.
*/
updatepri(td);
}
ts->ts_slptime = 0;
} else
ts->ts_slptime++;
if (ts->ts_slptime > 1) {
thread_unlock(td);
continue;
}
ts->ts_estcpu = decay_cpu(loadfac, ts->ts_estcpu);
resetpriority(td);
resetpriority_thread(td);
thread_unlock(td);
}
PROC_UNLOCK(p);
}
sx_sunlock(&allproc_lock);
}
/*
* Main loop for a kthread that executes schedcpu once a second.
*/
static void
schedcpu_thread(void)
{
for (;;) {
schedcpu();
pause("-", hz);
}
}
/*
* Recalculate the priority of a process after it has slept for a while.
* For all load averages >= 1 and max ts_estcpu of 255, sleeping for at
* least six times the loadfactor will decay ts_estcpu to zero.
*/
static void
updatepri(struct thread *td)
{
struct td_sched *ts;
fixpt_t loadfac;
unsigned int newcpu;
ts = td_get_sched(td);
loadfac = loadfactor(averunnable.ldavg[0]);
if (ts->ts_slptime > 5 * loadfac)
ts->ts_estcpu = 0;
else {
newcpu = ts->ts_estcpu;
ts->ts_slptime--; /* was incremented in schedcpu() */
while (newcpu && --ts->ts_slptime)
newcpu = decay_cpu(loadfac, newcpu);
ts->ts_estcpu = newcpu;
}
}
/*
* Compute the priority of a process when running in user mode.
* Arrange to reschedule if the resulting priority is better
* than that of the current process.
*/
static void
resetpriority(struct thread *td)
{
u_int newpriority;
if (td->td_pri_class != PRI_TIMESHARE)
return;
newpriority = PUSER +
td_get_sched(td)->ts_estcpu / INVERSE_ESTCPU_WEIGHT +
NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN);
newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
PRI_MAX_TIMESHARE);
sched_user_prio(td, newpriority);
}
/*
* Update the thread's priority when the associated process's user
* priority changes.
*/
static void
resetpriority_thread(struct thread *td)
{
/* Only change threads with a time sharing user priority. */
if (td->td_priority < PRI_MIN_TIMESHARE ||
td->td_priority > PRI_MAX_TIMESHARE)
return;
/* XXX the whole needresched thing is broken, but not silly. */
maybe_resched(td);
sched_prio(td, td->td_user_pri);
}
/* ARGSUSED */
static void
sched_setup(void *dummy)
{
setup_runqs();
/* Account for thread0. */
sched_load_add();
}
/*
* This routine determines time constants after stathz and hz are setup.
*/
static void
sched_initticks(void *dummy)
{
realstathz = stathz ? stathz : hz;
sched_slice = realstathz / 10; /* ~100ms */
hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
realstathz);
}
/* External interfaces start here */
/*
* Very early in the boot some setup of scheduler-specific
* parts of proc0 and of some scheduler resources needs to be done.
* Called from:
* proc0_init()
*/
void
schedinit(void)
{
/*
* Set up the scheduler specific parts of thread0.
*/
thread0.td_lock = &sched_lock;
td_get_sched(&thread0)->ts_slice = sched_slice;
mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN);
}
int
sched_runnable(void)
{
#ifdef SMP
return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]);
#else
return runq_check(&runq);
#endif
}
int
sched_rr_interval(void)
{
/* Convert sched_slice from stathz to hz. */
return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
}
/*
* We adjust the priority of the current process. The priority of a
* process gets worse as it accumulates CPU time. The cpu usage
* estimator (ts_estcpu) is increased here. resetpriority() will
* compute a different priority each time ts_estcpu increases by
* INVERSE_ESTCPU_WEIGHT (until PRI_MAX_TIMESHARE is reached). The
* cpu usage estimator ramps up quite quickly when the process is
* running (linearly), and decays away exponentially, at a rate which
* is proportionally slower when the system is busy. The basic
* principle is that the system will 90% forget that the process used
* a lot of CPU time in 5 * loadav seconds. This causes the system to
* favor processes which haven't run much recently, and to round-robin
* among other processes.
*/
static void
sched_clock_tick(struct thread *td)
{
struct pcpuidlestat *stat;
struct td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td_get_sched(td);
ts->ts_cpticks++;
ts->ts_estcpu = ESTCPULIM(ts->ts_estcpu + 1);
if ((ts->ts_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
resetpriority(td);
resetpriority_thread(td);
}
/*
* Force a context switch if the current thread has used up a full
* time slice (default is 100ms).
*/
if (!TD_IS_IDLETHREAD(td) && --ts->ts_slice <= 0) {
ts->ts_slice = sched_slice;
td->td_flags |= TDF_NEEDRESCHED | TDF_SLICEEND;
}
stat = DPCPU_PTR(idlestat);
stat->oldidlecalls = stat->idlecalls;
stat->idlecalls = 0;
}
void
sched_clock(struct thread *td, int cnt)
{
for ( ; cnt > 0; cnt--)
sched_clock_tick(td);
}
/*
* Charge child's scheduling CPU usage to parent.
*/
void
sched_exit(struct proc *p, struct thread *td)
{
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit",
"prio:%d", td->td_priority);
PROC_LOCK_ASSERT(p, MA_OWNED);
sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
}
void
sched_exit_thread(struct thread *td, struct thread *child)
{
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit",
"prio:%d", child->td_priority);
thread_lock(td);
td_get_sched(td)->ts_estcpu = ESTCPULIM(td_get_sched(td)->ts_estcpu +
td_get_sched(child)->ts_estcpu);
thread_unlock(td);
thread_lock(child);
if ((child->td_flags & TDF_NOLOAD) == 0)
sched_load_rem();
thread_unlock(child);
}
void
sched_fork(struct thread *td, struct thread *childtd)
{
sched_fork_thread(td, childtd);
}
void
sched_fork_thread(struct thread *td, struct thread *childtd)
{
struct td_sched *ts, *tsc;
childtd->td_oncpu = NOCPU;
childtd->td_lastcpu = NOCPU;
childtd->td_lock = &sched_lock;
childtd->td_cpuset = cpuset_ref(td->td_cpuset);
childtd->td_domain.dr_policy = td->td_cpuset->cs_domain;
childtd->td_priority = childtd->td_base_pri;
ts = td_get_sched(childtd);
bzero(ts, sizeof(*ts));
tsc = td_get_sched(td);
ts->ts_estcpu = tsc->ts_estcpu;
ts->ts_flags |= (tsc->ts_flags & TSF_AFFINITY);
ts->ts_slice = 1;
}
void
sched_nice(struct proc *p, int nice)
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
p->p_nice = nice;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
resetpriority(td);
resetpriority_thread(td);
thread_unlock(td);
}
}
void
sched_class(struct thread *td, int class)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_pri_class = class;
}
/*
* Adjust the priority of a thread.
*/
static void
sched_priority(struct thread *td, u_char prio)
{
KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change",
"prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED,
sched_tdname(curthread));
SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
if (td != curthread && prio > td->td_priority) {
KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
"lend prio", "prio:%d", td->td_priority, "new prio:%d",
prio, KTR_ATTR_LINKED, sched_tdname(td));
SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
curthread);
}
THREAD_LOCK_ASSERT(td, MA_OWNED);
if (td->td_priority == prio)
return;
td->td_priority = prio;
if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) {
sched_rem(td);
sched_add(td, SRQ_BORING | SRQ_HOLDTD);
}
}
/*
* 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_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 regulary 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_prio(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_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)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_base_user_pri = prio;
if (td->td_lend_user_pri <= prio)
return;
td->td_user_pri = prio;
}
void
sched_lend_user_prio(struct thread *td, u_char prio)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_lend_user_pri = prio;
td->td_user_pri = min(prio, td->td_base_user_pri);
if (td->td_priority > td->td_user_pri)
sched_prio(td, td->td_user_pri);
else if (td->td_priority != td->td_user_pri)
td->td_flags |= TDF_NEEDRESCHED;
}
/*
* Like the above but first check if there is anything to do.
*/
void
sched_lend_user_prio_cond(struct thread *td, u_char prio)
{
if (td->td_lend_user_pri != prio)
goto lend;
if (td->td_user_pri != min(prio, td->td_base_user_pri))
goto lend;
if (td->td_priority != td->td_user_pri)
goto lend;
return;
lend:
thread_lock(td);
sched_lend_user_prio(td, prio);
thread_unlock(td);
}
void
sched_sleep(struct thread *td, int pri)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_slptick = ticks;
td_get_sched(td)->ts_slptime = 0;
if (pri != 0 && PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
sched_prio(td, pri);
if (TD_IS_SUSPENDED(td) || pri >= PSOCK)
td->td_flags |= TDF_CANSWAP;
}
void
sched_switch(struct thread *td, int flags)
{
struct thread *newtd;
struct mtx *tmtx;
struct td_sched *ts;
struct proc *p;
int preempted;
tmtx = &sched_lock;
ts = td_get_sched(td);
p = td->td_proc;
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_lastcpu = td->td_oncpu;
preempted = (td->td_flags & TDF_SLICEEND) == 0 &&
(flags & SW_PREEMPT) != 0;
td->td_flags &= ~(TDF_NEEDRESCHED | TDF_SLICEEND);
td->td_owepreempt = 0;
td->td_oncpu = NOCPU;
/*
* At the last moment, if this thread is still marked RUNNING,
* then put it back on the run queue as it has not been suspended
* or stopped or any thing else similar. We never put the idle
* threads on the run queue, however.
*/
if (td->td_flags & TDF_IDLETD) {
TD_SET_CAN_RUN(td);
#ifdef SMP
CPU_CLR(PCPU_GET(cpuid), &idle_cpus_mask);
#endif
} else {
if (TD_IS_RUNNING(td)) {
/* Put us back on the run queue. */
sched_add(td, preempted ?
SRQ_HOLDTD|SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
SRQ_HOLDTD|SRQ_OURSELF|SRQ_YIELDING);
}
}
/*
* Switch to the sched lock to fix things up and pick
* a new thread. Block the td_lock in order to avoid
* breaking the critical path.
*/
if (td->td_lock != &sched_lock) {
mtx_lock_spin(&sched_lock);
tmtx = thread_lock_block(td);
mtx_unlock_spin(tmtx);
}
if ((td->td_flags & TDF_NOLOAD) == 0)
sched_load_rem();
newtd = choosethread();
MPASS(newtd->td_lock == &sched_lock);
#if (KTR_COMPILE & KTR_SCHED) != 0
if (TD_IS_IDLETHREAD(td))
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle",
"prio:%d", td->td_priority);
else
KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td),
"prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg,
"lockname:\"%s\"", td->td_lockname);
#endif
if (td != newtd) {
#ifdef HWPMC_HOOKS
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
#endif
SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
/* I feel sleepy */
lock_profile_release_lock(&sched_lock.lock_object, true);
#ifdef KDTRACE_HOOKS
/*
* If DTrace has set the active vtime enum to anything
* other than INACTIVE (0), then it should have set the
* function to call.
*/
if (dtrace_vtime_active)
(*dtrace_vtime_switch_func)(newtd);
#endif
cpu_switch(td, newtd, tmtx);
lock_profile_obtain_lock_success(&sched_lock.lock_object, true,
0, 0, __FILE__, __LINE__);
/*
* Where am I? What year is it?
* We are in the same thread that went to sleep above,
* but any amount of time may have passed. All our context
* will still be available as will local variables.
* PCPU values however may have changed as we may have
* changed CPU so don't trust cached values of them.
* New threads will go to fork_exit() instead of here
* so if you change things here you may need to change
* things there too.
*
* If the thread above was exiting it will never wake
* up again here, so either it has saved everything it
* needed to, or the thread_wait() or wait() will
* need to reap it.
*/
SDT_PROBE0(sched, , , on__cpu);
#ifdef HWPMC_HOOKS
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
#endif
} else {
td->td_lock = &sched_lock;
SDT_PROBE0(sched, , , remain__cpu);
}
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
"prio:%d", td->td_priority);
#ifdef SMP
if (td->td_flags & TDF_IDLETD)
CPU_SET(PCPU_GET(cpuid), &idle_cpus_mask);
#endif
sched_lock.mtx_lock = (uintptr_t)td;
td->td_oncpu = PCPU_GET(cpuid);
spinlock_enter();
mtx_unlock_spin(&sched_lock);
}
void
sched_wakeup(struct thread *td, int srqflags)
{
struct td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td_get_sched(td);
td->td_flags &= ~TDF_CANSWAP;
if (ts->ts_slptime > 1) {
updatepri(td);
resetpriority(td);
}
td->td_slptick = 0;
ts->ts_slptime = 0;
ts->ts_slice = sched_slice;
sched_add(td, srqflags);
}
#ifdef SMP
static int
forward_wakeup(int cpunum)
{
struct pcpu *pc;
cpuset_t dontuse, map, map2;
u_int id, me;
int iscpuset;
mtx_assert(&sched_lock, MA_OWNED);
CTR0(KTR_RUNQ, "forward_wakeup()");
if ((!forward_wakeup_enabled) ||
(forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0))
return (0);
if (!smp_started || KERNEL_PANICKED())
return (0);
forward_wakeups_requested++;
/*
* Check the idle mask we received against what we calculated
* before in the old version.
*/
me = PCPU_GET(cpuid);
/* Don't bother if we should be doing it ourself. */
if (CPU_ISSET(me, &idle_cpus_mask) &&
(cpunum == NOCPU || me == cpunum))
return (0);
CPU_SETOF(me, &dontuse);
CPU_OR(&dontuse, &stopped_cpus);
CPU_OR(&dontuse, &hlt_cpus_mask);
CPU_ZERO(&map2);
if (forward_wakeup_use_loop) {
STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
id = pc->pc_cpuid;
if (!CPU_ISSET(id, &dontuse) &&
pc->pc_curthread == pc->pc_idlethread) {
CPU_SET(id, &map2);
}
}
}
if (forward_wakeup_use_mask) {
map = idle_cpus_mask;
CPU_ANDNOT(&map, &dontuse);
/* If they are both on, compare and use loop if different. */
if (forward_wakeup_use_loop) {
if (CPU_CMP(&map, &map2)) {
printf("map != map2, loop method preferred\n");
map = map2;
}
}
} else {
map = map2;
}
/* If we only allow a specific CPU, then mask off all the others. */
if (cpunum != NOCPU) {
KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum."));
iscpuset = CPU_ISSET(cpunum, &map);
if (iscpuset == 0)
CPU_ZERO(&map);
else
CPU_SETOF(cpunum, &map);
}
if (!CPU_EMPTY(&map)) {
forward_wakeups_delivered++;
STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
id = pc->pc_cpuid;
if (!CPU_ISSET(id, &map))
continue;
if (cpu_idle_wakeup(pc->pc_cpuid))
CPU_CLR(id, &map);
}
if (!CPU_EMPTY(&map))
ipi_selected(map, IPI_AST);
return (1);
}
if (cpunum == NOCPU)
printf("forward_wakeup: Idle processor not found\n");
return (0);
}
static void
kick_other_cpu(int pri, int cpuid)
{
struct pcpu *pcpu;
int cpri;
pcpu = pcpu_find(cpuid);
if (CPU_ISSET(cpuid, &idle_cpus_mask)) {
forward_wakeups_delivered++;
if (!cpu_idle_wakeup(cpuid))
ipi_cpu(cpuid, IPI_AST);
return;
}
cpri = pcpu->pc_curthread->td_priority;
if (pri >= cpri)
return;
#if defined(IPI_PREEMPTION) && defined(PREEMPTION)
#if !defined(FULL_PREEMPTION)
if (pri <= PRI_MAX_ITHD)
#endif /* ! FULL_PREEMPTION */
{
ipi_cpu(cpuid, IPI_PREEMPT);
return;
}
#endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */
pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
ipi_cpu(cpuid, IPI_AST);
return;
}
#endif /* SMP */
#ifdef SMP
static int
sched_pickcpu(struct thread *td)
{
int best, cpu;
mtx_assert(&sched_lock, MA_OWNED);
if (td->td_lastcpu != NOCPU && THREAD_CAN_SCHED(td, td->td_lastcpu))
best = td->td_lastcpu;
else
best = NOCPU;
CPU_FOREACH(cpu) {
if (!THREAD_CAN_SCHED(td, cpu))
continue;
if (best == NOCPU)
best = cpu;
else if (runq_length[cpu] < runq_length[best])
best = cpu;
}
KASSERT(best != NOCPU, ("no valid CPUs"));
return (best);
}
#endif
void
sched_add(struct thread *td, int flags)
#ifdef SMP
{
cpuset_t tidlemsk;
struct td_sched *ts;
u_int cpu, cpuid;
int forwarded = 0;
int single_cpu = 0;
ts = td_get_sched(td);
THREAD_LOCK_ASSERT(td, MA_OWNED);
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_flags & TDF_INMEM,
("sched_add: thread swapped out"));
KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
"prio:%d", td->td_priority, KTR_ATTR_LINKED,
sched_tdname(curthread));
KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
KTR_ATTR_LINKED, sched_tdname(td));
SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
flags & SRQ_PREEMPTED);
/*
* 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);
if ((flags & SRQ_HOLD) != 0)
td->td_lock = &sched_lock;
else
thread_lock_set(td, &sched_lock);
}
TD_SET_RUNQ(td);
/*
* If SMP is started and the thread is pinned or otherwise limited to
* a specific set of CPUs, queue the thread to a per-CPU run queue.
* Otherwise, queue the thread to the global run queue.
*
* If SMP has not yet been started we must use the global run queue
* as per-CPU state may not be initialized yet and we may crash if we
* try to access the per-CPU run queues.
*/
if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND ||
ts->ts_flags & TSF_AFFINITY)) {
if (td->td_pinned != 0)
cpu = td->td_lastcpu;
else if (td->td_flags & TDF_BOUND) {
/* Find CPU from bound runq. */
KASSERT(SKE_RUNQ_PCPU(ts),
("sched_add: bound td_sched not on cpu runq"));
cpu = ts->ts_runq - &runq_pcpu[0];
} else
/* Find a valid CPU for our cpuset */
cpu = sched_pickcpu(td);
ts->ts_runq = &runq_pcpu[cpu];
single_cpu = 1;
CTR3(KTR_RUNQ,
"sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
cpu);
} else {
CTR2(KTR_RUNQ,
"sched_add: adding td_sched:%p (td:%p) to gbl runq", ts,
td);
cpu = NOCPU;
ts->ts_runq = &runq;
}
if ((td->td_flags & TDF_NOLOAD) == 0)
sched_load_add();
runq_add(ts->ts_runq, td, flags);
if (cpu != NOCPU)
runq_length[cpu]++;
cpuid = PCPU_GET(cpuid);
if (single_cpu && cpu != cpuid) {
kick_other_cpu(td->td_priority, cpu);
} else {
if (!single_cpu) {
tidlemsk = idle_cpus_mask;
CPU_ANDNOT(&tidlemsk, &hlt_cpus_mask);
CPU_CLR(cpuid, &tidlemsk);
if (!CPU_ISSET(cpuid, &idle_cpus_mask) &&
((flags & SRQ_INTR) == 0) &&
!CPU_EMPTY(&tidlemsk))
forwarded = forward_wakeup(cpu);
}
if (!forwarded) {
if (!maybe_preempt(td))
maybe_resched(td);
}
}
if ((flags & SRQ_HOLDTD) == 0)
thread_unlock(td);
}
#else /* SMP */
{
struct td_sched *ts;
ts = td_get_sched(td);
THREAD_LOCK_ASSERT(td, MA_OWNED);
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_flags & TDF_INMEM,
("sched_add: thread swapped out"));
KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
"prio:%d", td->td_priority, KTR_ATTR_LINKED,
sched_tdname(curthread));
KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
KTR_ATTR_LINKED, sched_tdname(td));
SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
flags & SRQ_PREEMPTED);
/*
* 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);
if ((flags & SRQ_HOLD) != 0)
td->td_lock = &sched_lock;
else
thread_lock_set(td, &sched_lock);
}
TD_SET_RUNQ(td);
CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td);
ts->ts_runq = &runq;
if ((td->td_flags & TDF_NOLOAD) == 0)
sched_load_add();
runq_add(ts->ts_runq, td, flags);
if (!maybe_preempt(td))
maybe_resched(td);
if ((flags & SRQ_HOLDTD) == 0)
thread_unlock(td);
}
#endif /* SMP */
void
sched_rem(struct thread *td)
{
struct td_sched *ts;
ts = td_get_sched(td);
KASSERT(td->td_flags & TDF_INMEM,
("sched_rem: thread swapped out"));
KASSERT(TD_ON_RUNQ(td),
("sched_rem: thread not on run queue"));
mtx_assert(&sched_lock, MA_OWNED);
KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
"prio:%d", td->td_priority, KTR_ATTR_LINKED,
sched_tdname(curthread));
SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
if ((td->td_flags & TDF_NOLOAD) == 0)
sched_load_rem();
#ifdef SMP
if (ts->ts_runq != &runq)
runq_length[ts->ts_runq - runq_pcpu]--;
#endif
runq_remove(ts->ts_runq, td);
TD_SET_CAN_RUN(td);
}
/*
* Select threads to run. Note that running threads still consume a
* slot.
*/
struct thread *
sched_choose(void)
{
struct thread *td;
struct runq *rq;
mtx_assert(&sched_lock, MA_OWNED);
#ifdef SMP
struct thread *tdcpu;
rq = &runq;
td = runq_choose_fuzz(&runq, runq_fuzz);
tdcpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]);
if (td == NULL ||
(tdcpu != NULL &&
tdcpu->td_priority < td->td_priority)) {
CTR2(KTR_RUNQ, "choosing td %p from pcpu runq %d", tdcpu,
PCPU_GET(cpuid));
td = tdcpu;
rq = &runq_pcpu[PCPU_GET(cpuid)];
} else {
CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", td);
}
#else
rq = &runq;
td = runq_choose(&runq);
#endif
if (td) {
#ifdef SMP
if (td == tdcpu)
runq_length[PCPU_GET(cpuid)]--;
#endif
runq_remove(rq, td);
td->td_flags |= TDF_DIDRUN;
KASSERT(td->td_flags & TDF_INMEM,
("sched_choose: thread swapped out"));
return (td);
}
return (PCPU_GET(idlethread));
}
void
sched_preempt(struct thread *td)
{
SDT_PROBE2(sched, , , surrender, td, td->td_proc);
if (td->td_critnest > 1) {
td->td_owepreempt = 1;
} else {
thread_lock(td);
mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT);
}
}
void
sched_userret_slowpath(struct thread *td)
{
thread_lock(td);
td->td_priority = td->td_user_pri;
td->td_base_pri = td->td_user_pri;
thread_unlock(td);
}
void
sched_bind(struct thread *td, int cpu)
{
struct td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
ts = td_get_sched(td);
td->td_flags |= TDF_BOUND;
#ifdef SMP
ts->ts_runq = &runq_pcpu[cpu];
if (PCPU_GET(cpuid) == cpu)
return;
mi_switch(SW_VOL);
thread_lock(td);
#endif
}
void
sched_unbind(struct thread* td)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
td->td_flags &= ~TDF_BOUND;
}
int
sched_is_bound(struct thread *td)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
return (td->td_flags & TDF_BOUND);
}
void
sched_relinquish(struct thread *td)
{
thread_lock(td);
mi_switch(SW_VOL | SWT_RELINQUISH);
}
int
sched_load(void)
{
return (sched_tdcnt);
}
int
sched_sizeof_proc(void)
{
return (sizeof(struct proc));
}
int
sched_sizeof_thread(void)
{
return (sizeof(struct thread) + sizeof(struct td_sched));
}
fixpt_t
sched_pctcpu(struct thread *td)
{
struct td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td_get_sched(td);
return (ts->ts_pctcpu);
}
#ifdef RACCT
/*
* Calculates the contribution to the thread cpu usage for the latest
* (unfinished) second.
*/
fixpt_t
sched_pctcpu_delta(struct thread *td)
{
struct td_sched *ts;
fixpt_t delta;
int realstathz;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td_get_sched(td);
delta = 0;
realstathz = stathz ? stathz : hz;
if (ts->ts_cpticks != 0) {
#if (FSHIFT >= CCPU_SHIFT)
delta = (realstathz == 100)
? ((fixpt_t) ts->ts_cpticks) <<
(FSHIFT - CCPU_SHIFT) :
100 * (((fixpt_t) ts->ts_cpticks)
<< (FSHIFT - CCPU_SHIFT)) / realstathz;
#else
delta = ((FSCALE - ccpu) *
(ts->ts_cpticks *
FSCALE / realstathz)) >> FSHIFT;
#endif
}
return (delta);
}
#endif
u_int
sched_estcpu(struct thread *td)
{
return (td_get_sched(td)->ts_estcpu);
}
/*
* The actual idle process.
*/
void
sched_idletd(void *dummy)
{
struct pcpuidlestat *stat;
THREAD_NO_SLEEPING();
stat = DPCPU_PTR(idlestat);
for (;;) {
mtx_assert(&Giant, MA_NOTOWNED);
while (sched_runnable() == 0) {
cpu_idle(stat->idlecalls + stat->oldidlecalls > 64);
stat->idlecalls++;
}
mtx_lock_spin(&sched_lock);
mi_switch(SW_VOL | SWT_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();
PCPU_SET(switchtime, cpu_ticks());
PCPU_SET(switchticks, ticks);
} else {
lock_profile_release_lock(&sched_lock.lock_object, true);
MPASS(td->td_lock == &sched_lock);
td->td_lastcpu = td->td_oncpu;
td->td_oncpu = NOCPU;
}
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(curthread->td_md.md_spinlock_count == 1, ("invalid count"));
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;
lock_profile_obtain_lock_success(&sched_lock.lock_object, true,
0, 0, __FILE__, __LINE__);
THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
"prio:%d", td->td_priority);
SDT_PROBE0(sched, , , on__cpu);
}
char *
sched_tdname(struct thread *td)
{
#ifdef KTR
struct td_sched *ts;
ts = td_get_sched(td);
if (ts->ts_name[0] == '\0')
snprintf(ts->ts_name, sizeof(ts->ts_name),
"%s tid %d", td->td_name, td->td_tid);
return (ts->ts_name);
#else
return (td->td_name);
#endif
}
#ifdef KTR
void
sched_clear_tdname(struct thread *td)
{
struct td_sched *ts;
ts = td_get_sched(td);
ts->ts_name[0] = '\0';
}
#endif
void
sched_affinity(struct thread *td)
{
#ifdef SMP
struct td_sched *ts;
int cpu;
THREAD_LOCK_ASSERT(td, MA_OWNED);
/*
* Set the TSF_AFFINITY flag if there is at least one CPU this
* thread can't run on.
*/
ts = td_get_sched(td);
ts->ts_flags &= ~TSF_AFFINITY;
CPU_FOREACH(cpu) {
if (!THREAD_CAN_SCHED(td, cpu)) {
ts->ts_flags |= TSF_AFFINITY;
break;
}
}
/*
* If this thread can run on all CPUs, nothing else to do.
*/
if (!(ts->ts_flags & TSF_AFFINITY))
return;
/* Pinned threads and bound threads should be left alone. */
if (td->td_pinned != 0 || td->td_flags & TDF_BOUND)
return;
switch (TD_GET_STATE(td)) {
case TDS_RUNQ:
/*
* If we are on a per-CPU runqueue that is in the set,
* then nothing needs to be done.
*/
if (ts->ts_runq != &runq &&
THREAD_CAN_SCHED(td, ts->ts_runq - runq_pcpu))
return;
/* Put this thread on a valid per-CPU runqueue. */
sched_rem(td);
sched_add(td, SRQ_HOLDTD | SRQ_BORING);
break;
case TDS_RUNNING:
/*
* See if our current CPU is in the set. If not, force a
* context switch.
*/
if (THREAD_CAN_SCHED(td, td->td_oncpu))
return;
td->td_flags |= TDF_NEEDRESCHED;
if (td != curthread)
ipi_cpu(cpu, IPI_AST);
break;
default:
break;
}
#endif
}
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