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freebsd/sys/kern/sched_4bsd.c

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/*-
* 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.
* 4. 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"
#define kse td_sched
#include <sys/param.h>
#include <sys/systm.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/smp.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/turnstile.h>
#include <machine/pcb.h>
#include <machine/smp.h>
#ifdef HWPMC_HOOKS
#include <sys/pmckern.h>
#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. */
/*
* The schedulable entity that can be given a context to run.
* A process may have several of these. Probably one per processor
* but possibly a few more. In this universe they are grouped
* with a KSEG that contains the priority and niceness
* for the group.
*/
struct kse {
TAILQ_ENTRY(kse) ke_procq; /* (j/z) Run queue. */
struct thread *ke_thread; /* (*) Active associated thread. */
fixpt_t ke_pctcpu; /* (j) %cpu during p_swtime. */
u_char ke_rqindex; /* (j) Run queue index. */
enum {
KES_THREAD = 0x0, /* slaved to thread state */
KES_ONRUNQ
} ke_state; /* (j) KSE status. */
int ke_cpticks; /* (j) Ticks of cpu time. */
struct runq *ke_runq; /* runq the kse is currently on */
};
#define ke_proc ke_thread->td_proc
#define ke_ksegrp ke_thread->td_ksegrp
#define td_kse td_sched
/* flags kept in td_flags */
#define TDF_DIDRUN TDF_SCHED0 /* KSE actually ran. */
#define TDF_EXIT TDF_SCHED1 /* KSE is being killed. */
#define TDF_BOUND TDF_SCHED2
#define ke_flags ke_thread->td_flags
#define KEF_DIDRUN TDF_DIDRUN /* KSE actually ran. */
#define KEF_EXIT TDF_EXIT /* KSE is being killed. */
#define KEF_BOUND TDF_BOUND /* stuck to one CPU */
#define SKE_RUNQ_PCPU(ke) \
((ke)->ke_runq != 0 && (ke)->ke_runq != &runq)
struct kg_sched {
struct thread *skg_last_assigned; /* (j) Last thread assigned to */
/* the system scheduler. */
int skg_avail_opennings; /* (j) Num KSEs requested in group. */
int skg_concurrency; /* (j) Num KSEs requested in group. */
};
#define kg_last_assigned kg_sched->skg_last_assigned
#define kg_avail_opennings kg_sched->skg_avail_opennings
#define kg_concurrency kg_sched->skg_concurrency
#define SLOT_RELEASE(kg) \
do { \
kg->kg_avail_opennings++; \
CTR3(KTR_RUNQ, "kg %p(%d) Slot released (->%d)", \
kg, \
kg->kg_concurrency, \
kg->kg_avail_opennings); \
/* KASSERT((kg->kg_avail_opennings <= kg->kg_concurrency), \
("slots out of whack"));*/ \
} while (0)
#define SLOT_USE(kg) \
do { \
kg->kg_avail_opennings--; \
CTR3(KTR_RUNQ, "kg %p(%d) Slot used (->%d)", \
kg, \
kg->kg_concurrency, \
kg->kg_avail_opennings); \
/* KASSERT((kg->kg_avail_opennings >= 0), \
("slots out of whack"));*/ \
} while (0)
/*
* KSE_CAN_MIGRATE macro returns true if the kse can migrate between
* cpus.
*/
#define KSE_CAN_MIGRATE(ke) \
((ke)->ke_thread->td_pinned == 0 && ((ke)->ke_flags & KEF_BOUND) == 0)
static struct kse kse0;
static struct kg_sched kg_sched0;
static int sched_tdcnt; /* Total runnable threads in the system. */
static int sched_quantum; /* Roundrobin scheduling quantum in ticks. */
#define SCHED_QUANTUM (hz / 10) /* Default sched quantum */
static struct callout roundrobin_callout;
static void slot_fill(struct ksegrp *kg);
static struct kse *sched_choose(void); /* XXX Should be thread * */
static void setup_runqs(void);
static void roundrobin(void *arg);
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 ksegrp *kg);
static void resetpriority(struct ksegrp *kg);
static void resetpriority_thread(struct thread *td, struct ksegrp *kg);
#ifdef SMP
static int forward_wakeup(int cpunum);
#endif
static struct kproc_desc sched_kp = {
"schedcpu",
schedcpu_thread,
NULL
};
SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start, &sched_kp)
SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL)
/*
* Global run queue.
*/
static struct runq runq;
#ifdef SMP
/*
* Per-CPU run queues
*/
static struct runq runq_pcpu[MAXCPU];
#endif
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;
new_val = sched_quantum * tick;
error = sysctl_handle_int(oidp, &new_val, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
if (new_val < tick)
return (EINVAL);
sched_quantum = new_val / tick;
hogticks = 2 * sched_quantum;
return (0);
}
SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 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,
0, sizeof sched_quantum, sysctl_kern_quantum, "I",
"Roundrobin scheduling quantum in microseconds");
#ifdef SMP
/* Enable forwarding of wakeups to all other cpus */
SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP");
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");
static int forward_wakeup_use_single = 0;
SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW,
&forward_wakeup_use_single, 0,
"Only signal one idle cpu");
static int forward_wakeup_use_htt = 0;
SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW,
&forward_wakeup_use_htt, 0,
"account for htt");
#endif
static int sched_followon = 0;
SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW,
&sched_followon, 0,
"allow threads to share a quantum");
static int sched_pfollowons = 0;
SYSCTL_INT(_kern_sched, OID_AUTO, pfollowons, CTLFLAG_RD,
&sched_pfollowons, 0,
"number of followons done to a different ksegrp");
static int sched_kgfollowons = 0;
SYSCTL_INT(_kern_sched, OID_AUTO, kgfollowons, CTLFLAG_RD,
&sched_kgfollowons, 0,
"number of followons done in a ksegrp");
static __inline void
sched_load_add(void)
{
sched_tdcnt++;
CTR1(KTR_SCHED, "global load: %d", sched_tdcnt);
}
static __inline void
sched_load_rem(void)
{
sched_tdcnt--;
CTR1(KTR_SCHED, "global load: %d", sched_tdcnt);
}
/*
* Arrange to reschedule if necessary, taking the priorities and
* schedulers into account.
*/
static void
maybe_resched(struct thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
if (td->td_priority < curthread->td_priority)
curthread->td_flags |= TDF_NEEDRESCHED;
}
/*
* Force switch among equal priority processes every 100ms.
* We don't actually need to force a context switch of the current process.
* The act of firing the event triggers a context switch to softclock() and
* then switching back out again which is equivalent to a preemption, thus
* no further work is needed on the local CPU.
*/
/* ARGSUSED */
static void
roundrobin(void *arg)
{
#ifdef SMP
mtx_lock_spin(&sched_lock);
forward_roundrobin();
mtx_unlock_spin(&sched_lock);
#endif
callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL);
}
/*
* Constants for digital decay and forget:
* 90% of (kg_estcpu) usage in 5 * loadav time
* 95% of (ke_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 kg_estcpu and p_cpticks asynchronously.
*
* We wish to decay away 90% of kg_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++)
* kg_estcpu *= decay;
* will compute
* kg_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 `ke_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
/*
* 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)
{
register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
struct thread *td;
struct proc *p;
struct kse *ke;
struct ksegrp *kg;
int awake, realstathz;
realstathz = stathz ? stathz : hz;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
/*
* Prevent state changes and protect run queue.
*/
mtx_lock_spin(&sched_lock);
/*
* Increment time in/out of memory. We ignore overflow; with
* 16-bit int's (remember them?) overflow takes 45 days.
*/
p->p_swtime++;
FOREACH_KSEGRP_IN_PROC(p, kg) {
awake = 0;
FOREACH_THREAD_IN_GROUP(kg, td) {
ke = td->td_kse;
/*
* Increment sleep time (if sleeping). We
* ignore overflow, as above.
*/
/*
* The kse slptimes are not touched in wakeup
* because the thread may not HAVE a KSE.
*/
if (ke->ke_state == KES_ONRUNQ) {
awake = 1;
ke->ke_flags &= ~KEF_DIDRUN;
} else if ((ke->ke_state == KES_THREAD) &&
(TD_IS_RUNNING(td))) {
awake = 1;
/* Do not clear KEF_DIDRUN */
} else if (ke->ke_flags & KEF_DIDRUN) {
awake = 1;
ke->ke_flags &= ~KEF_DIDRUN;
}
/*
* ke_pctcpu is only for ps and ttyinfo().
* Do it per kse, and add them up at the end?
* XXXKSE
*/
ke->ke_pctcpu = (ke->ke_pctcpu * ccpu) >>
FSHIFT;
/*
* If the kse has been idle the entire second,
* stop recalculating its priority until
* it wakes up.
*/
if (ke->ke_cpticks == 0)
continue;
#if (FSHIFT >= CCPU_SHIFT)
ke->ke_pctcpu += (realstathz == 100)
? ((fixpt_t) ke->ke_cpticks) <<
(FSHIFT - CCPU_SHIFT) :
100 * (((fixpt_t) ke->ke_cpticks)
<< (FSHIFT - CCPU_SHIFT)) / realstathz;
#else
ke->ke_pctcpu += ((FSCALE - ccpu) *
(ke->ke_cpticks *
FSCALE / realstathz)) >> FSHIFT;
#endif
ke->ke_cpticks = 0;
} /* end of kse loop */
/*
* If there are ANY running threads in this KSEGRP,
* then don't count it as sleeping.
*/
if (awake) {
if (kg->kg_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(kg);
}
kg->kg_slptime = 0;
} else
kg->kg_slptime++;
if (kg->kg_slptime > 1)
continue;
kg->kg_estcpu = decay_cpu(loadfac, kg->kg_estcpu);
resetpriority(kg);
FOREACH_THREAD_IN_GROUP(kg, td) {
resetpriority_thread(td, kg);
}
} /* end of ksegrp loop */
mtx_unlock_spin(&sched_lock);
} /* end of process loop */
sx_sunlock(&allproc_lock);
}
/*
* Main loop for a kthread that executes schedcpu once a second.
*/
static void
schedcpu_thread(void)
{
int nowake;
for (;;) {
schedcpu();
tsleep(&nowake, 0, "-", hz);
}
}
/*
* Recalculate the priority of a process after it has slept for a while.
* For all load averages >= 1 and max kg_estcpu of 255, sleeping for at
* least six times the loadfactor will decay kg_estcpu to zero.
*/
static void
updatepri(struct ksegrp *kg)
{
register fixpt_t loadfac;
register unsigned int newcpu;
loadfac = loadfactor(averunnable.ldavg[0]);
if (kg->kg_slptime > 5 * loadfac)
kg->kg_estcpu = 0;
else {
newcpu = kg->kg_estcpu;
kg->kg_slptime--; /* was incremented in schedcpu() */
while (newcpu && --kg->kg_slptime)
newcpu = decay_cpu(loadfac, newcpu);
kg->kg_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 ksegrp *kg)
{
register unsigned int newpriority;
if (kg->kg_pri_class == PRI_TIMESHARE) {
newpriority = PUSER + kg->kg_estcpu / INVERSE_ESTCPU_WEIGHT +
NICE_WEIGHT * (kg->kg_proc->p_nice - PRIO_MIN);
newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
PRI_MAX_TIMESHARE);
kg->kg_user_pri = newpriority;
}
}
/*
* Update the thread's priority when the associated ksegroup's user
* priority changes.
*/
static void
resetpriority_thread(struct thread *td, struct ksegrp *kg)
{
/* 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, kg->kg_user_pri);
}
/* ARGSUSED */
static void
sched_setup(void *dummy)
{
setup_runqs();
if (sched_quantum == 0)
sched_quantum = SCHED_QUANTUM;
hogticks = 2 * sched_quantum;
callout_init(&roundrobin_callout, CALLOUT_MPSAFE);
/* Kick off timeout driven events by calling first time. */
roundrobin(NULL);
/* Account for thread0. */
sched_load_add();
}
/* 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 proc0.
*/
proc0.p_sched = NULL; /* XXX */
ksegrp0.kg_sched = &kg_sched0;
thread0.td_sched = &kse0;
kse0.ke_thread = &thread0;
kse0.ke_state = KES_THREAD;
kg_sched0.skg_concurrency = 1;
kg_sched0.skg_avail_opennings = 0; /* we are already running */
}
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)
{
if (sched_quantum == 0)
sched_quantum = SCHED_QUANTUM;
return (sched_quantum);
}
/*
* We adjust the priority of the current process. The priority of
* a process gets worse as it accumulates CPU time. The cpu usage
* estimator (kg_estcpu) is increased here. resetpriority() will
* compute a different priority each time kg_estcpu increases by
* INVERSE_ESTCPU_WEIGHT
* (until MAXPRI 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.
*/
void
sched_clock(struct thread *td)
{
struct ksegrp *kg;
struct kse *ke;
mtx_assert(&sched_lock, MA_OWNED);
kg = td->td_ksegrp;
ke = td->td_kse;
ke->ke_cpticks++;
kg->kg_estcpu = ESTCPULIM(kg->kg_estcpu + 1);
if ((kg->kg_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
resetpriority(kg);
resetpriority_thread(td, kg);
}
}
/*
* charge childs scheduling cpu usage to parent.
*
* XXXKSE assume only one thread & kse & ksegrp keep estcpu in each ksegrp.
* Charge it to the ksegrp that did the wait since process estcpu is sum of
* all ksegrps, this is strictly as expected. Assume that the child process
* aggregated all the estcpu into the 'built-in' ksegrp.
*/
void
sched_exit(struct proc *p, struct thread *td)
{
sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), td);
sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
}
void
sched_exit_ksegrp(struct ksegrp *kg, struct thread *childtd)
{
mtx_assert(&sched_lock, MA_OWNED);
kg->kg_estcpu = ESTCPULIM(kg->kg_estcpu + childtd->td_ksegrp->kg_estcpu);
}
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);
if ((child->td_proc->p_flag & P_NOLOAD) == 0)
sched_load_rem();
}
void
sched_fork(struct thread *td, struct thread *childtd)
{
sched_fork_ksegrp(td, childtd->td_ksegrp);
sched_fork_thread(td, childtd);
}
void
sched_fork_ksegrp(struct thread *td, struct ksegrp *child)
{
mtx_assert(&sched_lock, MA_OWNED);
child->kg_estcpu = td->td_ksegrp->kg_estcpu;
}
void
sched_fork_thread(struct thread *td, struct thread *childtd)
{
sched_newthread(childtd);
}
void
sched_nice(struct proc *p, int nice)
{
struct ksegrp *kg;
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
mtx_assert(&sched_lock, MA_OWNED);
p->p_nice = nice;
FOREACH_KSEGRP_IN_PROC(p, kg) {
resetpriority(kg);
FOREACH_THREAD_IN_GROUP(kg, td) {
resetpriority_thread(td, kg);
}
}
}
void
sched_class(struct ksegrp *kg, int class)
{
mtx_assert(&sched_lock, MA_OWNED);
kg->kg_pri_class = class;
}
/*
* Adjust the priority of a thread.
* This may include moving the thread within the KSEGRP,
* changing the assignment of a kse to the thread,
* and moving a KSE in the system run queue.
*/
static void
sched_priority(struct thread *td, u_char prio)
{
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);
mtx_assert(&sched_lock, MA_OWNED);
if (td->td_priority == prio)
return;
if (TD_ON_RUNQ(td)) {
adjustrunqueue(td, prio);
} 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_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_ksegrp->kg_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_sleep(struct thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_ksegrp->kg_slptime = 0;
}
static void remrunqueue(struct thread *td);
void
sched_switch(struct thread *td, struct thread *newtd, int flags)
{
struct kse *ke;
struct ksegrp *kg;
struct proc *p;
ke = td->td_kse;
p = td->td_proc;
mtx_assert(&sched_lock, MA_OWNED);
if ((p->p_flag & P_NOLOAD) == 0)
sched_load_rem();
/*
* We are volunteering to switch out so we get to nominate
* a successor for the rest of our quantum
* First try another thread in our ksegrp, and then look for
* other ksegrps in our process.
*/
if (sched_followon &&
(p->p_flag & P_HADTHREADS) &&
(flags & SW_VOL) &&
newtd == NULL) {
/* lets schedule another thread from this process */
kg = td->td_ksegrp;
if ((newtd = TAILQ_FIRST(&kg->kg_runq))) {
remrunqueue(newtd);
sched_kgfollowons++;
} else {
FOREACH_KSEGRP_IN_PROC(p, kg) {
if ((newtd = TAILQ_FIRST(&kg->kg_runq))) {
sched_pfollowons++;
remrunqueue(newtd);
break;
}
}
}
}
if (newtd)
newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED);
td->td_lastcpu = td->td_oncpu;
td->td_flags &= ~TDF_NEEDRESCHED;
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 == PCPU_GET(idlethread))
TD_SET_CAN_RUN(td);
else {
SLOT_RELEASE(td->td_ksegrp);
if (TD_IS_RUNNING(td)) {
/* Put us back on the run queue (kse and all). */
setrunqueue(td, (flags & SW_PREEMPT) ?
SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
SRQ_OURSELF|SRQ_YIELDING);
} else if (p->p_flag & P_HADTHREADS) {
/*
* We will not be on the run queue. So we must be
* sleeping or similar. As it's available,
* someone else can use the KSE if they need it.
* It's NOT available if we are about to need it
*/
if (newtd == NULL || newtd->td_ksegrp != td->td_ksegrp)
slot_fill(td->td_ksegrp);
}
}
if (newtd) {
/*
* The thread we are about to run needs to be counted
* as if it had been added to the run queue and selected.
* It came from:
* * A preemption
* * An upcall
* * A followon
*/
KASSERT((newtd->td_inhibitors == 0),
("trying to run inhibitted thread"));
SLOT_USE(newtd->td_ksegrp);
newtd->td_kse->ke_flags |= KEF_DIDRUN;
TD_SET_RUNNING(newtd);
if ((newtd->td_proc->p_flag & P_NOLOAD) == 0)
sched_load_add();
} 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);
#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);
}
void
sched_wakeup(struct thread *td)
{
struct ksegrp *kg;
mtx_assert(&sched_lock, MA_OWNED);
kg = td->td_ksegrp;
if (kg->kg_slptime > 1) {
updatepri(kg);
resetpriority(kg);
}
kg->kg_slptime = 0;
setrunqueue(td, SRQ_BORING);
}
#ifdef SMP
/* enable HTT_2 if you have a 2-way HTT cpu.*/
static int
forward_wakeup(int cpunum)
{
cpumask_t map, me, dontuse;
cpumask_t map2;
struct pcpu *pc;
cpumask_t id, map3;
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 || cold || panicstr)
return (0);
forward_wakeups_requested++;
/*
* check the idle mask we received against what we calculated before
* in the old version.
*/
me = PCPU_GET(cpumask);
/*
* don't bother if we should be doing it ourself..
*/
if ((me & idle_cpus_mask) && (cpunum == NOCPU || me == (1 << cpunum)))
return (0);
dontuse = me | stopped_cpus | hlt_cpus_mask;
map3 = 0;
if (forward_wakeup_use_loop) {
SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
id = pc->pc_cpumask;
if ( (id & dontuse) == 0 &&
pc->pc_curthread == pc->pc_idlethread) {
map3 |= id;
}
}
}
if (forward_wakeup_use_mask) {
map = 0;
map = idle_cpus_mask & ~dontuse;
/* If they are both on, compare and use loop if different */
if (forward_wakeup_use_loop) {
if (map != map3) {
printf("map (%02X) != map3 (%02X)\n",
map, map3);
map = map3;
}
}
} else {
map = map3;
}
/* If we only allow a specific CPU, then mask off all the others */
if (cpunum != NOCPU) {
KASSERT((cpunum <= mp_maxcpus),("forward_wakeup: bad cpunum."));
map &= (1 << cpunum);
} else {
/* Try choose an idle die. */
if (forward_wakeup_use_htt) {
map2 = (map & (map >> 1)) & 0x5555;
if (map2) {
map = map2;
}
}
/* set only one bit */
if (forward_wakeup_use_single) {
map = map & ((~map) + 1);
}
}
if (map) {
forward_wakeups_delivered++;
ipi_selected(map, IPI_AST);
return (1);
}
if (cpunum == NOCPU)
printf("forward_wakeup: Idle processor not found\n");
return (0);
}
#endif
#ifdef SMP
static void kick_other_cpu(int pri,int cpuid);
static void
kick_other_cpu(int pri,int cpuid)
{
struct pcpu * pcpu = pcpu_find(cpuid);
int cpri = pcpu->pc_curthread->td_priority;
if (idle_cpus_mask & pcpu->pc_cpumask) {
forward_wakeups_delivered++;
ipi_selected(pcpu->pc_cpumask, IPI_AST);
return;
}
if (pri >= cpri)
return;
#if defined(IPI_PREEMPTION) && defined(PREEMPTION)
#if !defined(FULL_PREEMPTION)
if (pri <= PRI_MAX_ITHD)
#endif /* ! FULL_PREEMPTION */
{
ipi_selected(pcpu->pc_cpumask, IPI_PREEMPT);
return;
}
#endif /* defined(IPI_PREEMPTION) && defined(PREEMPTION) */
pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
ipi_selected( pcpu->pc_cpumask , IPI_AST);
return;
}
#endif /* SMP */
void
sched_add(struct thread *td, int flags)
#ifdef SMP
{
struct kse *ke;
int forwarded = 0;
int cpu;
int single_cpu = 0;
ke = td->td_kse;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(ke->ke_state != KES_ONRUNQ,
("sched_add: kse %p (%s) already in run queue", ke,
ke->ke_proc->p_comm));
KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
("sched_add: process swapped out"));
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);
if (td->td_pinned != 0) {
cpu = td->td_lastcpu;
ke->ke_runq = &runq_pcpu[cpu];
single_cpu = 1;
CTR3(KTR_RUNQ,
"sched_add: Put kse:%p(td:%p) on cpu%d runq", ke, td, cpu);
} else if ((ke)->ke_flags & KEF_BOUND) {
/* Find CPU from bound runq */
KASSERT(SKE_RUNQ_PCPU(ke),("sched_add: bound kse not on cpu runq"));
cpu = ke->ke_runq - &runq_pcpu[0];
single_cpu = 1;
CTR3(KTR_RUNQ,
"sched_add: Put kse:%p(td:%p) on cpu%d runq", ke, td, cpu);
} else {
CTR2(KTR_RUNQ,
"sched_add: adding kse:%p (td:%p) to gbl runq", ke, td);
cpu = NOCPU;
ke->ke_runq = &runq;
}
if (single_cpu && (cpu != PCPU_GET(cpuid))) {
kick_other_cpu(td->td_priority,cpu);
} else {
if (!single_cpu) {
cpumask_t me = PCPU_GET(cpumask);
int idle = idle_cpus_mask & me;
if (!idle && ((flags & SRQ_INTR) == 0) &&
(idle_cpus_mask & ~(hlt_cpus_mask | me)))
forwarded = forward_wakeup(cpu);
}
if (!forwarded) {
if ((flags & SRQ_YIELDING) == 0 && maybe_preempt(td))
return;
else
maybe_resched(td);
}
}
if ((td->td_proc->p_flag & P_NOLOAD) == 0)
sched_load_add();
SLOT_USE(td->td_ksegrp);
runq_add(ke->ke_runq, ke, flags);
ke->ke_state = KES_ONRUNQ;
}
#else /* SMP */
{
struct kse *ke;
ke = td->td_kse;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(ke->ke_state != KES_ONRUNQ,
("sched_add: kse %p (%s) already in run queue", ke,
ke->ke_proc->p_comm));
KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
("sched_add: process swapped out"));
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);
CTR2(KTR_RUNQ, "sched_add: adding kse:%p (td:%p) to runq", ke, td);
ke->ke_runq = &runq;
/*
* If we are yielding (on the way out anyhow)
* or the thread being saved is US,
* then don't try be smart about preemption
* or kicking off another CPU
* as it won't help and may hinder.
* In the YIEDLING case, we are about to run whoever is
* being put in the queue anyhow, and in the
* OURSELF case, we are puting ourself on the run queue
* which also only happens when we are about to yield.
*/
if((flags & SRQ_YIELDING) == 0) {
if (maybe_preempt(td))
return;
}
if ((td->td_proc->p_flag & P_NOLOAD) == 0)
sched_load_add();
SLOT_USE(td->td_ksegrp);
runq_add(ke->ke_runq, ke, flags);
ke->ke_state = KES_ONRUNQ;
maybe_resched(td);
}
#endif /* SMP */
void
sched_rem(struct thread *td)
{
struct kse *ke;
ke = td->td_kse;
KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
("sched_rem: process swapped out"));
KASSERT((ke->ke_state == KES_ONRUNQ),
("sched_rem: KSE not on run queue"));
mtx_assert(&sched_lock, MA_OWNED);
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);
if ((td->td_proc->p_flag & P_NOLOAD) == 0)
sched_load_rem();
SLOT_RELEASE(td->td_ksegrp);
runq_remove(ke->ke_runq, ke);
ke->ke_state = KES_THREAD;
}
/*
* Select threads to run.
* Notice that the running threads still consume a slot.
*/
struct kse *
sched_choose(void)
{
struct kse *ke;
struct runq *rq;
#ifdef SMP
struct kse *kecpu;
rq = &runq;
ke = runq_choose(&runq);
kecpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]);
if (ke == NULL ||
(kecpu != NULL &&
kecpu->ke_thread->td_priority < ke->ke_thread->td_priority)) {
CTR2(KTR_RUNQ, "choosing kse %p from pcpu runq %d", kecpu,
PCPU_GET(cpuid));
ke = kecpu;
rq = &runq_pcpu[PCPU_GET(cpuid)];
} else {
CTR1(KTR_RUNQ, "choosing kse %p from main runq", ke);
}
#else
rq = &runq;
ke = runq_choose(&runq);
#endif
if (ke != NULL) {
runq_remove(rq, ke);
ke->ke_state = KES_THREAD;
KASSERT(ke->ke_proc->p_sflag & PS_INMEM,
("sched_choose: process swapped out"));
}
return (ke);
}
void
sched_userret(struct thread *td)
{
struct ksegrp *kg;
/*
* 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"));
kg = td->td_ksegrp;
if (td->td_priority != kg->kg_user_pri) {
mtx_lock_spin(&sched_lock);
td->td_priority = kg->kg_user_pri;
td->td_base_pri = kg->kg_user_pri;
mtx_unlock_spin(&sched_lock);
}
}
void
sched_bind(struct thread *td, int cpu)
{
struct kse *ke;
mtx_assert(&sched_lock, MA_OWNED);
KASSERT(TD_IS_RUNNING(td),
("sched_bind: cannot bind non-running thread"));
ke = td->td_kse;
ke->ke_flags |= KEF_BOUND;
#ifdef SMP
ke->ke_runq = &runq_pcpu[cpu];
if (PCPU_GET(cpuid) == cpu)
return;
ke->ke_state = KES_THREAD;
mi_switch(SW_VOL, NULL);
#endif
}
void
sched_unbind(struct thread* td)
{
mtx_assert(&sched_lock, MA_OWNED);
td->td_kse->ke_flags &= ~KEF_BOUND;
}
int
sched_is_bound(struct thread *td)
{
mtx_assert(&sched_lock, MA_OWNED);
return (td->td_kse->ke_flags & KEF_BOUND);
}
void
sched_relinquish(struct thread *td)
{
struct ksegrp *kg;
kg = td->td_ksegrp;
mtx_lock_spin(&sched_lock);
if (kg->kg_pri_class == PRI_TIMESHARE)
sched_prio(td, PRI_MAX_TIMESHARE);
mi_switch(SW_VOL, NULL);
mtx_unlock_spin(&sched_lock);
}
int
sched_load(void)
{
return (sched_tdcnt);
}
int
sched_sizeof_ksegrp(void)
{
return (sizeof(struct ksegrp) + sizeof(struct kg_sched));
}
int
sched_sizeof_proc(void)
{
return (sizeof(struct proc));
}
int
sched_sizeof_thread(void)
{
return (sizeof(struct thread) + sizeof(struct kse));
}
fixpt_t
sched_pctcpu(struct thread *td)
{
struct kse *ke;
ke = td->td_kse;
return (ke->ke_pctcpu);
}
void
sched_tick(void)
{
}
#define KERN_SWITCH_INCLUDE 1
#include "kern/kern_switch.c"
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