Messages in this thread Patch in this message | | | From | riel@redhat ... | Subject | [PATCH 2/4] sched: simplify wake_affine for single socket case | Date | Fri, 23 Jun 2017 12:55:28 -0400 |
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From: Rik van Riel <riel@redhat.com>
Then this_cpu and prev_cpu are in the same socket, select_idle_sibling will do its thing regardless of the return value of wake_affine. Just return true and don't look at all the other things.
Signed-off-by: Rik van Riel <riel@redhat.com> --- kernel/sched/fair.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2180c8591e16..949de24e36bd 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5373,6 +5373,13 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, this_load = target_load(this_cpu, idx); /* + * Common case: CPUs are in the same socket, and select_idle_sibling + * will do its thing regardless of what we return. + */ + if (cpus_share_cache(prev_cpu, this_cpu)) + return true; + + /* * If sync wakeup then subtract the (maximum possible) * effect of the currently running task from the load * of the current CPU: @@ -5960,11 +5967,15 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f if (affine_sd) { sd = NULL; /* Prefer wake_affine over balance flags */ - if (cpu != prev_cpu && wake_affine(affine_sd, p, prev_cpu, sync)) + if (cpu == prev_cpu) + goto pick_cpu; + + if (wake_affine(affine_sd, p, prev_cpu, sync)) new_cpu = cpu; } if (!sd) { + pick_cpu: if (sd_flag & SD_BALANCE_WAKE) /* XXX always ? */ new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); -- 2.9.4
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