sched/topology: Don't set SD_BALANCE_WAKE on cpuset domain relax

As pointed out in commit

  182a85f8a119 ("sched: Disable wakeup balancing")

SD_BALANCE_WAKE is a tad too aggressive, and is usually left unset.

However, it turns out cpuset domain relaxation will unconditionally set it
on domains below the relaxation level. This made sense back when
SD_BALANCE_WAKE was set unconditionally, but it no longer is the case.

We can improve things slightly by noticing that set_domain_attribute() is
always called after sd_init(), so rather than setting flags we can rely on
whatever sd_init() is doing and only clear certain flags when above the
relaxation level.

While at it, slightly clean up the function and flip the relax level
check to be more human readable.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mingo@kernel.org
Cc: vincent.guittot@linaro.org
Cc: juri.lelli@redhat.com
Cc: seto.hidetoshi@jp.fujitsu.com
Cc: qperret@google.com
Cc: Dietmar.Eggemann@arm.com
Cc: morten.rasmussen@arm.com
Link: https://lkml.kernel.org/r/20191014164408.32596-1-valentin.schneider@arm.com

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index b5667a273bf67e0718371a783b259ffb4c91cbc7..3623ffe85d18e4c3c3ea0d8bdc6b30bef99fdac0 100644 (file)
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1201,16 +1201,13 @@ static void set_domain_attribute(struct sched_domain *sd,
        if (!attr || attr->relax_domain_level < 0) {
                if (default_relax_domain_level < 0)
                        return;
-               else
-                       request = default_relax_domain_level;
+               request = default_relax_domain_level;
        } else
                request = attr->relax_domain_level;
-       if (request < sd->level) {
+
+       if (sd->level > request) {
                /* Turn off idle balance on this domain: */
                sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
-       } else {
-               /* Turn on idle balance on this domain: */
-               sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
        }
 }