cpuset: avoid unnecessary sched domains rebuilding
When changing 'sched_relax_domain_level', don't rebuild sched domains if
'cpus' is empty or 'sched_load_balance' is not set.
Also make the comments of rebuild_sched_domains() more readable.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 6eae663..60d2c47 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -496,11 +496,16 @@
/*
* rebuild_sched_domains()
*
- * If the flag 'sched_load_balance' of any cpuset with non-empty
- * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
- * which has that flag enabled, or if any cpuset with a non-empty
- * 'cpus' is removed, then call this routine to rebuild the
- * scheduler's dynamic sched domains.
+ * This routine will be called to rebuild the scheduler's dynamic
+ * sched domains:
+ * - if the flag 'sched_load_balance' of any cpuset with non-empty
+ * 'cpus' changes,
+ * - or if the 'cpus' allowed changes in any cpuset which has that
+ * flag enabled,
+ * - or if the 'sched_relax_domain_level' of any cpuset which has
+ * that flag enabled and with non-empty 'cpus' changes,
+ * - or if any cpuset with non-empty 'cpus' is removed,
+ * - or if a cpu gets offlined.
*
* This routine builds a partial partition of the systems CPUs
* (the set of non-overlappping cpumask_t's in the array 'part'
@@ -1076,7 +1081,8 @@
if (val != cs->relax_domain_level) {
cs->relax_domain_level = val;
- rebuild_sched_domains();
+ if (!cpus_empty(cs->cpus_allowed) && is_sched_load_balance(cs))
+ rebuild_sched_domains();
}
return 0;