freebsd-skq/sys/kern/sched_4bsd.c
Jeff Roberson c5aa6b581d - Pass the priority argument from *sleep() into sleepq and down into
sched_sleep().  This removes extra thread_lock() acquisition and
   allows the scheduler to decide what to do with the static boost.
 - Change the priority arguments to cv_* to match sleepq/msleep/etc.
   where 0 means no priority change.  Catch -1 in cv_broadcastpri() and
   convert it to 0 for now.
 - Set a flag when sleeping in a way that is compatible with swapping
   since direct priority comparisons are meaningless now.
 - Add a sysctl to ule, kern.sched.static_boost, that defaults to on which
   controls the boost behavior.  Turning it off gives better performance
   in some workloads but needs more investigation.
 - While we're modifying sleepq, change signal and broadcast to both
   return with the lock held as the lock was held on enter.

Reviewed by:	jhb, peter
2008-03-12 06:31:06 +00:00

1430 lines
36 KiB
C

/*-
* 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"
#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/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
/*
* 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 runs a context.
* This is an extension to the thread structure and is tailored to
* the requirements of this scheduler
*/
struct td_sched {
TAILQ_ENTRY(td_sched) ts_procq; /* (j/z) Run queue. */
struct thread *ts_thread; /* (*) Active associated thread. */
fixpt_t ts_pctcpu; /* (j) %cpu during p_swtime. */
u_char ts_rqindex; /* (j) Run queue index. */
int ts_cpticks; /* (j) Ticks of cpu time. */
int ts_slptime; /* (j) Seconds !RUNNING. */
struct runq *ts_runq; /* runq the thread is currently on */
};
/* flags kept in td_flags */
#define TDF_DIDRUN TDF_SCHED0 /* thread actually ran. */
#define TDF_EXIT TDF_SCHED1 /* thread is being killed. */
#define TDF_BOUND TDF_SCHED2
#define ts_flags ts_thread->td_flags
#define TSF_DIDRUN TDF_DIDRUN /* thread actually ran. */
#define TSF_EXIT TDF_EXIT /* thread is being killed. */
#define TSF_BOUND TDF_BOUND /* stuck to one CPU */
#define SKE_RUNQ_PCPU(ts) \
((ts)->ts_runq != 0 && (ts)->ts_runq != &runq)
static struct td_sched td_sched0;
struct mtx sched_lock;
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 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 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
#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
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)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
if (td->td_priority < curthread->td_priority)
curthread->td_flags |= TDF_NEEDRESCHED;
}
/*
* Constants for digital decay and forget:
* 90% of (td_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 td_estcpu and p_cpticks asynchronously.
*
* We wish to decay away 90% of td_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++)
* td_estcpu *= decay;
* will compute
* td_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_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 td_sched *ts;
int awake, realstathz;
realstathz = stathz ? stathz : hz;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
PROC_SLOCK(p);
FOREACH_THREAD_IN_PROC(p, td) {
awake = 0;
thread_lock(td);
ts = td->td_sched;
/*
* 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;
ts->ts_flags &= ~TSF_DIDRUN;
} else if (TD_IS_RUNNING(td)) {
awake = 1;
/* Do not clear TSF_DIDRUN */
} else if (ts->ts_flags & TSF_DIDRUN) {
awake = 1;
ts->ts_flags &= ~TSF_DIDRUN;
}
/*
* ts_pctcpu is only for ps and ttyinfo().
* Do it per td_sched, and add them up at the end?
* XXXKSE
*/
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;
}
td->td_estcpu = decay_cpu(loadfac, td->td_estcpu);
resetpriority(td);
resetpriority_thread(td);
thread_unlock(td);
} /* end of thread loop */
PROC_SUNLOCK(p);
} /* end of process loop */
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 td_estcpu of 255, sleeping for at
* least six times the loadfactor will decay td_estcpu to zero.
*/
static void
updatepri(struct thread *td)
{
struct td_sched *ts;
fixpt_t loadfac;
unsigned int newcpu;
ts = td->td_sched;
loadfac = loadfactor(averunnable.ldavg[0]);
if (ts->ts_slptime > 5 * loadfac)
td->td_estcpu = 0;
else {
newcpu = td->td_estcpu;
ts->ts_slptime--; /* was incremented in schedcpu() */
while (newcpu && --ts->ts_slptime)
newcpu = decay_cpu(loadfac, newcpu);
td->td_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)
{
register unsigned int newpriority;
if (td->td_pri_class == PRI_TIMESHARE) {
newpriority = PUSER + td->td_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();
if (sched_quantum == 0)
sched_quantum = SCHED_QUANTUM;
hogticks = 2 * sched_quantum;
/* 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 */
thread0.td_sched = &td_sched0;
thread0.td_lock = &sched_lock;
td_sched0.ts_thread = &thread0;
mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
}
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 (td_estcpu) is increased here. resetpriority() will
* compute a different priority each time td_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 td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td->td_sched;
ts->ts_cpticks++;
td->td_estcpu = ESTCPULIM(td->td_estcpu + 1);
if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
resetpriority(td);
resetpriority_thread(td);
}
/*
* Force a context switch if the current thread has used up a full
* quantum (default quantum is 100ms).
*/
if (!TD_IS_IDLETHREAD(td) &&
ticks - PCPU_GET(switchticks) >= sched_quantum)
td->td_flags |= TDF_NEEDRESCHED;
}
/*
* charge childs scheduling cpu usage to parent.
*/
void
sched_exit(struct proc *p, struct thread *td)
{
CTR3(KTR_SCHED, "sched_exit: %p(%s) prio %d",
td, td->td_name, td->td_priority);
PROC_SLOCK_ASSERT(p, MA_OWNED);
sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
}
void
sched_exit_thread(struct thread *td, struct thread *child)
{
CTR3(KTR_SCHED, "sched_exit_thread: %p(%s) prio %d",
child, child->td_name, child->td_priority);
thread_lock(td);
td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu);
thread_unlock(td);
mtx_lock_spin(&sched_lock);
if ((child->td_proc->p_flag & P_NOLOAD) == 0)
sched_load_rem();
mtx_unlock_spin(&sched_lock);
}
void
sched_fork(struct thread *td, struct thread *childtd)
{
sched_fork_thread(td, childtd);
}
void
sched_fork_thread(struct thread *td, struct thread *childtd)
{
childtd->td_estcpu = td->td_estcpu;
childtd->td_lock = &sched_lock;
childtd->td_cpuset = cpuset_ref(td->td_cpuset);
sched_newthread(childtd);
}
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);
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)
{
CTR6(KTR_SCHED, "sched_prio: %p(%s) prio %d newprio %d by %p(%s)",
td, td->td_name, td->td_priority, prio, curthread,
curthread->td_name);
THREAD_LOCK_ASSERT(td, MA_OWNED);
if (td->td_priority == prio)
return;
td->td_priority = prio;
if (TD_ON_RUNQ(td) &&
td->td_sched->ts_rqindex != (prio / RQ_PPQ)) {
sched_rem(td);
sched_add(td, SRQ_BORING);
}
}
/*
* 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)
{
u_char oldprio;
THREAD_LOCK_ASSERT(td, MA_OWNED);
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;
}
void
sched_lend_user_prio(struct thread *td, u_char prio)
{
u_char oldprio;
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_flags |= TDF_UBORROWING;
oldprio = td->td_user_pri;
td->td_user_pri = prio;
}
void
sched_unlend_user_prio(struct thread *td, u_char prio)
{
u_char base_pri;
THREAD_LOCK_ASSERT(td, MA_OWNED);
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_sleep(struct thread *td, int pri)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_slptick = ticks;
td->td_sched->ts_slptime = 0;
if (pri)
sched_prio(td, pri);
if (TD_IS_SUSPENDED(td) || pri <= PSOCK)
td->td_flags |= TDF_CANSWAP;
}
void
sched_switch(struct thread *td, struct thread *newtd, int flags)
{
struct td_sched *ts;
struct proc *p;
ts = td->td_sched;
p = td->td_proc;
THREAD_LOCK_ASSERT(td, MA_OWNED);
/*
* 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 ((p->p_flag & P_NOLOAD) == 0)
sched_load_rem();
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->td_flags & TDF_IDLETD) {
TD_SET_CAN_RUN(td);
#ifdef SMP
idle_cpus_mask &= ~PCPU_GET(cpumask);
#endif
} else {
if (TD_IS_RUNNING(td)) {
/* Put us back on the run queue. */
sched_add(td, (flags & SW_PREEMPT) ?
SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
SRQ_OURSELF|SRQ_YIELDING);
}
}
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 inhibited thread"));
newtd->td_sched->ts_flags |= TSF_DIDRUN;
TD_SET_RUNNING(newtd);
if ((newtd->td_proc->p_flag & P_NOLOAD) == 0)
sched_load_add();
} else {
newtd = choosethread();
}
MPASS(newtd->td_lock == &sched_lock);
if (td != newtd) {
#ifdef HWPMC_HOOKS
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
#endif
/* I feel sleepy */
lock_profile_release_lock(&sched_lock.lock_object);
cpu_switch(td, newtd, td->td_lock);
lock_profile_obtain_lock_success(&sched_lock.lock_object,
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 out 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.
*/
#ifdef HWPMC_HOOKS
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
#endif
}
#ifdef SMP
if (td->td_flags & TDF_IDLETD)
idle_cpus_mask |= PCPU_GET(cpumask);
#endif
sched_lock.mtx_lock = (uintptr_t)td;
td->td_oncpu = PCPU_GET(cpuid);
MPASS(td->td_lock == &sched_lock);
}
void
sched_wakeup(struct thread *td)
{
struct td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED);
ts = td->td_sched;
td->td_flags &= ~TDF_CANSWAP;
if (ts->ts_slptime > 1) {
updatepri(td);
resetpriority(td);
}
td->td_slptick = ticks;
ts->ts_slptime = 0;
sched_add(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 td_sched *ts;
int forwarded = 0;
int cpu;
int single_cpu = 0;
ts = td->td_sched;
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"));
CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)",
td, td->td_name, td->td_priority, curthread,
curthread->td_name);
/*
* 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);
}
TD_SET_RUNQ(td);
if (td->td_pinned != 0) {
cpu = td->td_lastcpu;
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 if ((ts)->ts_flags & TSF_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];
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 (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();
runq_add(ts->ts_runq, ts, flags);
}
#else /* SMP */
{
struct td_sched *ts;
ts = td->td_sched;
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"));
CTR5(KTR_SCHED, "sched_add: %p(%s) prio %d by %p(%s)",
td, td->td_name, td->td_priority, curthread,
curthread->td_name);
/*
* 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);
}
TD_SET_RUNQ(td);
CTR2(KTR_RUNQ, "sched_add: adding td_sched:%p (td:%p) to runq", ts, td);
ts->ts_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();
runq_add(ts->ts_runq, ts, flags);
maybe_resched(td);
}
#endif /* SMP */
void
sched_rem(struct thread *td)
{
struct td_sched *ts;
ts = td->td_sched;
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);
CTR5(KTR_SCHED, "sched_rem: %p(%s) prio %d by %p(%s)",
td, td->td_name, td->td_priority, curthread,
curthread->td_name);
if ((td->td_proc->p_flag & P_NOLOAD) == 0)
sched_load_rem();
runq_remove(ts->ts_runq, ts);
TD_SET_CAN_RUN(td);
}
/*
* Select threads to run.
* Notice that the running threads still consume a slot.
*/
struct thread *
sched_choose(void)
{
struct td_sched *ts;
struct runq *rq;
mtx_assert(&sched_lock, MA_OWNED);
#ifdef SMP
struct td_sched *kecpu;
rq = &runq;
ts = runq_choose(&runq);
kecpu = runq_choose(&runq_pcpu[PCPU_GET(cpuid)]);
if (ts == NULL ||
(kecpu != NULL &&
kecpu->ts_thread->td_priority < ts->ts_thread->td_priority)) {
CTR2(KTR_RUNQ, "choosing td_sched %p from pcpu runq %d", kecpu,
PCPU_GET(cpuid));
ts = kecpu;
rq = &runq_pcpu[PCPU_GET(cpuid)];
} else {
CTR1(KTR_RUNQ, "choosing td_sched %p from main runq", ts);
}
#else
rq = &runq;
ts = runq_choose(&runq);
#endif
if (ts) {
runq_remove(rq, ts);
ts->ts_flags |= TSF_DIDRUN;
KASSERT(ts->ts_thread->td_flags & TDF_INMEM,
("sched_choose: thread swapped out"));
return (ts->ts_thread);
}
return (PCPU_GET(idlethread));
}
void
sched_preempt(struct thread *td)
{
thread_lock(td);
if (td->td_critnest > 1)
td->td_owepreempt = 1;
else
mi_switch(SW_INVOL | SW_PREEMPT, NULL);
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_bind(struct thread *td, int cpu)
{
struct td_sched *ts;
THREAD_LOCK_ASSERT(td, MA_OWNED);
KASSERT(TD_IS_RUNNING(td),
("sched_bind: cannot bind non-running thread"));
ts = td->td_sched;
ts->ts_flags |= TSF_BOUND;
#ifdef SMP
ts->ts_runq = &runq_pcpu[cpu];
if (PCPU_GET(cpuid) == cpu)
return;
mi_switch(SW_VOL, NULL);
#endif
}
void
sched_unbind(struct thread* td)
{
THREAD_LOCK_ASSERT(td, MA_OWNED);
td->td_sched->ts_flags &= ~TSF_BOUND;
}
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);
SCHED_STAT_INC(switch_relinquish);
mi_switch(SW_VOL, NULL);
thread_unlock(td);
}
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;
ts = td->td_sched;
return (ts->ts_pctcpu);
}
void
sched_tick(void)
{
}
/*
* The actual idle process.
*/
void
sched_idletd(void *dummy)
{
for (;;) {
mtx_assert(&Giant, MA_NOTOWNED);
while (sched_runnable() == 0)
cpu_idle();
mtx_lock_spin(&sched_lock);
mi_switch(SW_VOL, NULL);
mtx_unlock_spin(&sched_lock);
}
}
/*
* 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 {
lock_profile_release_lock(&sched_lock.lock_object);
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;
lock_profile_obtain_lock_success(&sched_lock.lock_object,
0, 0, __FILE__, __LINE__);
THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
}
void
sched_affinity(struct thread *td)
{
}
#define KERN_SWITCH_INCLUDE 1
#include "kern/kern_switch.c"