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- In kseq_choose(), don't recalculate slice values for processes with a

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nice of 0.  Doing so can cause an infinite loop because they should be
   running, but a nice -20 process could prevent them from doing so.
 - Add a new flag KEF_PRIOELEV to flag a thread that has had its priority
   elevated due to priority propagation.  If a thread has had its priority
   elevated, we assume that it must go on the current queue and it must
   get a slice.
 - In sched_userret() if our priority was elevated and we shouldn't have
   a timeslice, yield here until we should.

Found/Tested by:	glebius
This commit is contained in:
Jeff Roberson 2004-12-14 10:34:27 +00:00
parent 2a9e0c3216
commit 8ffb8f5558
1 changed files with 25 additions and 11 deletions
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36
sys/kern/sched_ule.c
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@ -121,7 +121,8 @@ struct kse {
#define KEF_SCHED1 0x00002 /* For scheduler-specific use. */
#define KEF_SCHED2 0x00004 /* For scheduler-specific use. */
#define KEF_SCHED3 0x00008 /* For scheduler-specific use. */
#define KEF_SCHED4 0x00010
#define KEF_SCHED4 0x00010
#define KEF_SCHED5 0x00020
#define KEF_DIDRUN 0x02000 /* Thread actually ran. */
#define KEF_EXIT 0x04000 /* Thread is being killed. */
@ -136,7 +137,8 @@ struct kse {
#define KEF_BOUND KEF_SCHED1 /* Thread can not migrate. */
#define KEF_XFERABLE KEF_SCHED2 /* Thread was added as transferable. */
#define KEF_HOLD KEF_SCHED3 /* Thread is temporarily bound. */
#define KEF_REMOVED KEF_SCHED4
#define KEF_REMOVED KEF_SCHED4 /* Thread was removed while ASSIGNED */
#define KEF_PRIOELEV KEF_SCHED5 /* Thread has had its prio elevated. */
struct kg_sched {
struct thread *skg_last_assigned; /* (j) Last thread assigned to */
@ -238,8 +240,7 @@ static struct kg_sched kg_sched0;
#define SCHED_INTERACTIVE(kg) \
(sched_interact_score(kg) < SCHED_INTERACT_THRESH)
#define SCHED_CURR(kg, ke) \
(ke->ke_thread->td_priority < kg->kg_user_pri || \
SCHED_INTERACTIVE(kg))
((ke->ke_flags & KEF_PRIOELEV) || SCHED_INTERACTIVE(kg))
/*
* Cpu percentage computation macros and defines.
@ -885,11 +886,8 @@ kseq_choose(struct kseq *kseq)
* of the range that receives slices.
*/
nice = ke->ke_proc->p_nice + (0 - kseq->ksq_nicemin);
#ifdef notyet
if (ke->ke_slice == 0 || nice > SCHED_SLICE_NTHRESH) {
#else
if (ke->ke_slice == 0) {
#endif
if (ke->ke_slice == 0 || (nice > SCHED_SLICE_NTHRESH &&
ke->ke_proc->p_nice != 0)) {
runq_remove(ke->ke_runq, ke);
sched_slice(ke);
ke->ke_runq = kseq->ksq_next;
@ -1046,6 +1044,11 @@ sched_slice(struct kse *ke)
kg = ke->ke_ksegrp;
kseq = KSEQ_CPU(ke->ke_cpu);
if (ke->ke_flags & KEF_PRIOELEV) {
ke->ke_slice = SCHED_SLICE_MIN;
return;
}
/*
* Rationale:
* KSEs in interactive ksegs get a minimal slice so that we
@ -1224,13 +1227,15 @@ sched_prio(struct thread *td, u_char prio)
* queue. We still call adjustrunqueue below in case kse
* needs to fix things up.
*/
if (prio < td->td_priority && ke && ke->ke_runq != NULL &&
if (prio < td->td_priority && ke->ke_runq != NULL &&
(ke->ke_flags & KEF_ASSIGNED) == 0 &&
ke->ke_runq != KSEQ_CPU(ke->ke_cpu)->ksq_curr) {
runq_remove(ke->ke_runq, ke);
ke->ke_runq = KSEQ_CPU(ke->ke_cpu)->ksq_curr;
runq_add(ke->ke_runq, ke, 0);
}
if (prio < td->td_priority)
ke->ke_flags |= KEF_PRIOELEV;
/*
* Hold this kse on this cpu so that sched_prio() doesn't
* cause excessive migration. We only want migration to
@ -1631,12 +1636,21 @@ void
sched_userret(struct thread *td)
{
struct ksegrp *kg;
struct kse *ke;
kg = td->td_ksegrp;
ke = td->td_kse;
if (td->td_priority != kg->kg_user_pri) {
if (td->td_priority != kg->kg_user_pri ||
ke->ke_flags & KEF_PRIOELEV) {
mtx_lock_spin(&sched_lock);
td->td_priority = kg->kg_user_pri;
if (ke->ke_flags & KEF_PRIOELEV) {
ke->ke_flags &= ~KEF_PRIOELEV;
sched_slice(ke);
if (ke->ke_slice == 0)
mi_switch(SW_INVOL, NULL);
}
mtx_unlock_spin(&sched_lock);
}
}