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- Introduce a new flag KEF_HOLD that prevents sched_add() from doing a

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migration.  Use this in sched_prio() and sched_switch() to stop us from
   migrating threads that are in short term sleeps or are runnable.  These
   extra migrations were added in the patches to support KSE.
 - Only set NEEDRESCHED if the thread we're adding in sched_add() is a
   lower priority and is being placed on the current queue.
 - Fix some minor whitespace problems.
This commit is contained in:
jeff 2004-08-12 07:56:33 +00:00
parent e1b6157050
commit 8745e98dd0
1 changed files with 19 additions and 7 deletions
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26
sys/kern/sched_ule.c
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@ -51,7 +51,7 @@ __FBSDID("$FreeBSD$");
#include <machine/cpu.h>
#include <machine/smp.h>
#define KTR_ULE KTR_NFS
#define KTR_ULE KTR_NFS
/* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
/* XXX This is bogus compatability crap for ps */
@ -101,6 +101,7 @@ struct ke_sched {
#define KEF_ASSIGNED KEF_SCHED0 /* KSE is being migrated. */
#define KEF_BOUND KEF_SCHED1 /* KSE can not migrate. */
#define KEF_XFERABLE KEF_SCHED2 /* KSE was added as transferable. */
#define KEF_HOLD KEF_SCHED3 /* KSE is temporarily bound. */
struct kg_sched {
int skg_slptime; /* Number of ticks we vol. slept */
@ -1143,6 +1144,12 @@ sched_prio(struct thread *td, u_char prio)
ke->ke_runq = KSEQ_CPU(ke->ke_cpu)->ksq_curr;
runq_add(ke->ke_runq, ke);
}
/*
* Hold this kse on this cpu so that sched_prio() doesn't
* cause excessive migration. We only want migration to
* happen as the result of a wakeup.
*/
ke->ke_flags |= KEF_HOLD;
adjustrunqueue(td, prio);
} else
td->td_priority = prio;
@ -1158,7 +1165,7 @@ sched_switch(struct thread *td, struct thread *newtd)
ke = td->td_kse;
td->td_last_kse = ke;
td->td_lastcpu = td->td_oncpu;
td->td_lastcpu = td->td_oncpu;
td->td_oncpu = NOCPU;
td->td_flags &= ~TDF_NEEDRESCHED;
td->td_pflags &= ~TDP_OWEPREEMPT;
@ -1172,6 +1179,10 @@ sched_switch(struct thread *td, struct thread *newtd)
TD_SET_CAN_RUN(td);
} else if (TD_IS_RUNNING(td)) {
kseq_load_rem(KSEQ_CPU(ke->ke_cpu), ke);
/*
* Don't allow the kse to migrate from a preemption.
*/
ke->ke_flags |= KEF_HOLD;
setrunqueue(td);
} else {
if (ke->ke_runq) {
@ -1294,7 +1305,6 @@ sched_fork(struct thread *td, struct proc *p1)
void
sched_fork_kse(struct thread *td, struct kse *child)
{
struct kse *ke = td->td_kse;
child->ke_slice = 1; /* Attempt to quickly learn interactivity. */
@ -1642,9 +1652,10 @@ sched_add_internal(struct thread *td, int preemptive)
* to do it.
*/
canmigrate = KSE_CAN_MIGRATE(ke, class);
if (TD_IS_RUNNING(td))
if (ke->ke_flags & KEF_HOLD) {
ke->ke_flags &= ~KEF_HOLD;
canmigrate = 0;
}
/*
* If this thread is pinned or bound, notify the target cpu.
*/
@ -1678,8 +1689,9 @@ sched_add_internal(struct thread *td, int preemptive)
/*
* XXX With preemption this is not necessary.
*/
if (td->td_priority < curthread->td_priority)
curthread->td_flags |= TDF_NEEDRESCHED;
if (td->td_priority < curthread->td_priority &&
ke->ke_runq == kseq->ksq_curr)
curthread->td_flags |= TDF_NEEDRESCHED;
if (preemptive && maybe_preempt(td))
return;
ke->ke_ksegrp->kg_runq_kses++;