[tip: sched/core] sched/topology: Mark SD_SERIALIZE as SDF_NEEDS_GROUPS

[tip-bot2 for Valentin Schneider]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     bdb7c802cc0a7e21f5223dc3ce41b7ac220c576e
Gitweb:        https://git.kernel.org/tip/bdb7c802cc0a7e21f5223dc3ce41b7ac220c576e
Author:        Valentin Schneider <valentin.schneider@xxxxxxx>
AuthorDate:    Mon, 17 Aug 2020 12:29:59 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 19 Aug 2020 10:49:49 +02:00

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@xxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: https://lore.kernel.org/r/20200817113003.20802-14-valentin.schneider@xxxxxxx
---
 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 729510a..b7f4d80 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