Commit ab65afb0 authored Aug 17, 2020 by Valentin Schneider Committed by Ingo Molnar Aug 19, 2020

sched/topology: Remove SD_SERIALIZE degeneration special case



If there is only a single NUMA node in the system, the only NUMA topology
level that will be generated will be NODE (identity distance), which
doesn't have SD_SERIALIZE.

This means we don't need this special case in sd_parent_degenerate(), as
having the NODE level "naturally" covers it. Thus, remove it.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-10-valentin.schneider@arm.com

parent 6f349818

kernel/sched/topology.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -183,11 +183,9 @@ sd_parent_degenerate(struct sched_domain sd, struct sched_domain parent)
		return 0;

		/* Flags needing groups don't count if only 1 group in parent */
		if (parent->groups == parent->groups->next) {
		if (parent->groups == parent->groups->next)
		pflags &= ~(SD_DEGENERATE_GROUPS_MASK \| SD_PREFER_SIBLING);
		if (nr_node_ids == 1)
		pflags &= ~SD_SERIALIZE;
		}

		if (~cflags & pflags)
		return 0;

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