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Microoptimize sched_pickcpu() after r352658.

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I've noticed that I missed intr check at one more SCHED_AFFINITY(),
so instead of adding one more branching I prefer to remove few.

Profiler shows the function CPU time reduction from 0.24% to 0.16%.

MFC after:	1 month
Sponsored by:	iXsystems, Inc.
This commit is contained in:
mav 2019-09-25 19:29:09 +00:00
parent ca07d63db5
commit bd176423ea
1 changed files with 13 additions and 4 deletions
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17
sys/kern/sched_ule.c
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@ -1270,20 +1270,28 @@ sched_pickcpu(struct thread *td, int flags)
*/
if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) &&
curthread->td_intr_nesting_level) {
tdq = TDQ_SELF();
if (tdq->tdq_lowpri >= PRI_MIN_IDLE) {
SCHED_STAT_INC(pickcpu_idle_affinity);
return (self);
}
ts->ts_cpu = self;
intr = 1;
} else
cg = tdq->tdq_cg;
goto llc;
} else {
intr = 0;
tdq = TDQ_CPU(ts->ts_cpu);
cg = tdq->tdq_cg;
}
/*
* If the thread can run on the last cpu and the affinity has not
* expired and it is idle, run it there.
*/
tdq = TDQ_CPU(ts->ts_cpu);
cg = tdq->tdq_cg;
if (THREAD_CAN_SCHED(td, ts->ts_cpu) &&
tdq->tdq_lowpri >= PRI_MIN_IDLE &&
SCHED_AFFINITY(ts, CG_SHARE_L2)) {
if (!intr && cg->cg_flags & CG_FLAG_THREAD) {
if (cg->cg_flags & CG_FLAG_THREAD) {
CPUSET_FOREACH(cpu, cg->cg_mask) {
if (TDQ_CPU(cpu)->tdq_lowpri < PRI_MIN_IDLE)
break;
@ -1295,6 +1303,7 @@ sched_pickcpu(struct thread *td, int flags)
return (ts->ts_cpu);
}
}
llc:
/*
* Search for the last level cache CPU group in the tree.
* Skip SMT, identical groups and caches with expired affinity.