The following commit has been merged into the sched/core branch of tip:
Commit-ID: 872aa4de18889be63317a8c0f2de71a3a01e487c
Gitweb: https://git.kernel.org/tip/872aa4de18889be63317a8c0f2de71a3a01e487c
Author: K Prateek Nayak <kprateek.nayak@amd.com>
AuthorDate: Wed, 09 Apr 2025 05:34:43
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 16 Apr 2025 21:09:11 +02:00
sched/fair: Use READ_ONCE() to read sg->asym_prefer_cpu
Subsequent commits add the support to dynamically update the sched_group
struct's "asym_prefer_cpu" member from a remote CPU. Use READ_ONCE()
when reading the "sg->asym_prefer_cpu" to ensure load balancer always
reads the latest value.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409053446.23367-2-kprateek.nayak@amd.com
---
kernel/sched/fair.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0c19459..5e1bd9e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10251,7 +10251,7 @@ sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group
(sgs->group_weight - sgs->idle_cpus != 1))
return false;
- return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu);
+ return sched_asym(env->sd, env->dst_cpu, READ_ONCE(group->asym_prefer_cpu));
}
/* One group has more than one SMT CPU while the other group does not */
@@ -10488,7 +10488,8 @@ static bool update_sd_pick_busiest(struct lb_env *env,
case group_asym_packing:
/* Prefer to move from lowest priority CPU's work */
- return sched_asym_prefer(sds->busiest->asym_prefer_cpu, sg->asym_prefer_cpu);
+ return sched_asym_prefer(READ_ONCE(sds->busiest->asym_prefer_cpu),
+ READ_ONCE(sg->asym_prefer_cpu));
case group_misfit_task:
/*