sched/fair: Ignore cache hotness for SMT migration

SMT siblings share caches, so cache hotness should be irrelevant for
cross-sibling migration.

Signed-off-by: Josh Don <joshdon@google.com>
Proposed-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200804193413.510651-1-joshdon@google.com

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1a68a0536adda5257f44468451501ea1448d8005..abdb54e2339f454aae177c141f3f651bbd6f4559 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7402,6 +7402,10 @@ static int task_hot(struct task_struct *p, struct lb_env *env)
        if (unlikely(task_has_idle_policy(p)))
                return 0;
 
+       /* SMT siblings share cache */
+       if (env->sd->flags & SD_SHARE_CPUCAPACITY)
+               return 0;
+
        /*
         * Buddy candidates are cache hot:
         */