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sched/topology: Mark SD_PREFER_SIBLING as SDF_NEEDS_GROUPS 

SD_PREFER_SIBLING is currently considered in sd_parent_degenerate() but not
in sd_degenerate(). It too hinges on load balancing, and thus won't have
any effect when set on a domain with a single group. Add it to
SD_DEGENERATE_GROUPS_MASK.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-12-valentin.schneider@arm.com
This commit is contained in:
Valentin Schneider 2020-08-17 12:29:57 +01:00 committed by Ingo Molnar
parent c200191d4c
commit 3a6712c768
2 changed files with 4 additions and 2 deletions
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4
include/linux/sched/sd_flags.h
View File

@ -131,8 +131,10 @@ SD_FLAG(SD_ASYM_PACKING, SDF_SHARED_CHILD)
*
* Set up until domains start spanning NUMA nodes. Close to being a SHARED_CHILD
* flag, but cleared below domains with SD_ASYM_CPUCAPACITY.
*
* NEEDS_GROUPS: Load balancing flag.
*/
SD_FLAG(SD_PREFER_SIBLING, 0)
SD_FLAG(SD_PREFER_SIBLING, SDF_NEEDS_GROUPS)
/*
* sched_groups of this level overlap

2
kernel/sched/topology.c
View File

@ -184,7 +184,7 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
/* Flags needing groups don't count if only 1 group in parent */
if (parent->groups == parent->groups->next)
pflags &= ~(SD_DEGENERATE_GROUPS_MASK | SD_PREFER_SIBLING);
pflags &= ~SD_DEGENERATE_GROUPS_MASK;
if (~cflags & pflags)
return 0;