Re: [PATCH 2/3] sched,fair: Fix local starvation

[Mike Galbraith]

On Tue, 2016-05-10 at 19:43 +0200, Peter Zijlstra wrote:

(Evolution authors must either not do patch review, or use some other
mailer.  Squint hard, this crud really is your patch;)

> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
>  
> @@ -1762,7 +1770,11 @@ void sched_ttwu_pending(void)
>  > 	> while (llist) {
>  > 	> 	> p = llist_entry(llist, struct task_struct, wake_entry);
>  > 	> 	> llist = llist_next(llist);
> -> 	> 	> ttwu_do_activate(rq, p, 0, cookie);
> +> 	> 	> /*
> +> 	> 	>  * See ttwu_queue(); we only call ttwu_queue_remote() when
> +> 	> 	>  * its a x-cpu wakeup.
> +> 	> 	>  */
> +> 	> 	> ttwu_do_activate(rq, p, WF_MIGRATED, cookie);

Wakees that were not migrated/normalized eat an unwanted min_vruntime,
and likely take a size XXL latency hit.  Big box running master bled
profusely under heavy load until I turned TTWU_QUEUE off.

	-Mike