linux-kernel - [PATCH v5 13/17] sched/topology: Mark SD_SERIALIZE as SDF_NEEDS

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Date:   Wed, 12 Aug 2020 13:52:56 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     mingo@...nel.org, peterz@...radead.org, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, morten.rasmussen@....com,
        Quentin Perret <qperret@...gle.com>
Subject: [PATCH v5 13/17] sched/topology: Mark SD_SERIALIZE as SDF_NEEDS_GROUPS

There would be no point in preserving a sched_domain with a single group
just because it has this flag set. Add it to SD_DEGENERATE_GROUPS_MASK.

Signed-off-by: Valentin Schneider <valentin.schneider@....com>
---
 include/linux/sched/sd_flags.h | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched/sd_flags.h b/include/linux/sched/sd_flags.h
index 9043d18ce418..6eb302528659 100644
--- a/include/linux/sched/sd_flags.h
+++ b/include/linux/sched/sd_flags.h
@@ -112,11 +112,12 @@ SD_FLAG(SD_SHARE_PKG_RESOURCES, SDF_SHARED_CHILD | SDF_NEEDS_GROUPS)
  * Only a single load balancing instance
  *
  * SHARED_PARENT: Set for all NUMA levels above NODE. Could be set from a
- * different level upwards, but it doesn't change that if a domain has this flag
- * set, then all of its parents need to have it too (otherwise the serialization
- * doesn't make sense).
+ *                different level upwards, but it doesn't change that if a
+ *                domain has this flag set, then all of its parents need to have
+ *                it too (otherwise the serialization doesn't make sense).
+ * NEEDS_GROUPS: No point in preserving domain if it has a single group.
  */
-SD_FLAG(SD_SERIALIZE, SDF_SHARED_PARENT)
+SD_FLAG(SD_SERIALIZE, SDF_SHARED_PARENT | SDF_NEEDS_GROUPS)
 
 /*
  * Place busy tasks earlier in the domain
-- 
2.27.0