Author: mav
Date: Wed Sep 25 19:29:09 2019
New Revision: 352713
URL: https://svnweb.freebsd.org/changeset/base/352713
Log:
Microoptimize sched_pickcpu() after r352658.
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.
Modified:
head/sys/kern/sched_ule.c
Modified: head/sys/kern/sched_ule.c
==============================================================================
--- head/sys/kern/sched_ule.c Wed Sep 25 19:22:03 2019 (r352712)
+++ head/sys/kern/sched_ule.c Wed Sep 25 19:29:09 2019 (r352713)
@@ -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.
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