package/base/linux/0051-sched-fair-Ignore-cache-hotness-for-SMT-migration.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Josh Don <joshdon@google.com>
   3 Date: Tue, 4 Aug 2020 12:34:13 -0700
   4 Subject: [PATCH] sched/fair: Ignore cache hotness for SMT migration
   5
   6 commit  ec73240b1627cddfd7cef018c7fa1c32e64a721e upstream
   7
   8 SMT siblings share caches, so cache hotness should be irrelevant for
   9 cross-sibling migration.
  10
  11 Signed-off-by: Josh Don <joshdon@google.com>
  12 Proposed-by: Venkatesh Pallipadi <venki@google.com>
  13 Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
  14 Link: https://lkml.kernel.org/r/20200804193413.510651-1-joshdon@google.com
  15 ---
  16  kernel/sched/fair.c | 4 ++++
  17  1 file changed, 4 insertions(+)
  18
  19 diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
  20 index c0c4d9ad7da8..1c39dda88136 100644
  21 --- a/kernel/sched/fair.c
  22 +++ b/kernel/sched/fair.c
  23 @@ -7405,6 +7405,10 @@ static int task_hot(struct task_struct *p, struct lb_env *env)
  24         if (unlikely(task_has_idle_policy(p)))
  25                 return 0;
  26
  27 +       /* SMT siblings share cache */
  28 +       if (env->sd->flags & SD_SHARE_CPUCAPACITY)
  29 +               return 0;
  30 +
  31         /*
  32          * Buddy candidates are cache hot:
  33          */
  34 --
  35 https://clearlinux.org
  36