linux-kernel - [PATCH] sched/topology: Align group flags when removing degenerate domain

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Date:   Thu, 13 Jul 2023 09:31:33 +0800
From:   Chen Yu <yu.c.chen@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     Ricardo Neri <ricardo.neri@...el.com>,
        Tim Chen <tim.c.chen@...el.com>,
        Yicong Yang <yangyicong@...wei.com>,
        linux-kernel@...r.kernel.org, Chen Yu <yu.c.chen@...el.com>
Subject: [PATCH] sched/topology: Align group flags when removing degenerate domain

The flags of the child of a given scheduling domain are used to initialize
the flags of its scheduling groups. When the child of a scheduling domain
is degenerated, the flags of its local scheduling group need to be updated
to align with the flags of its new child domain.

The flag SD_SHARE_CPUCAPACITY was aligned in
Commit bf2dc42d6beb ("sched/topology: Propagate SMT flags when removing degenerate domain").
Further generalize this alignment so other flags can be used later, such as
in cluster-based task wakeup. [1]

Link: https://lore.kernel.org/lkml/20230530115527.GC156198@hirez.programming.kicks-ass.net #1
Suggested-by: Ricardo Neri <ricardo.neri@...el.com>
Reported-by: Yicong Yang <yangyicong@...wei.com>
Closes: https://lore.kernel.org/lkml/ce714341-af58-2522-69a8-321f02c82893@huawei.com/
Signed-off-by: Chen Yu <yu.c.chen@...el.com>
---
 kernel/sched/topology.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index d3a3b2646ec4..ff02d7deec0c 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -722,8 +722,7 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 
 			if (parent->parent) {
 				parent->parent->child = tmp;
-				if (tmp->flags & SD_SHARE_CPUCAPACITY)
-					parent->parent->groups->flags |= SD_SHARE_CPUCAPACITY;
+				parent->parent->groups->flags = tmp->flags;
 			}
 
 			/*
-- 
2.25.1