Re: [PATCH v2 00/19] Fixes for sched/numa_balancing

[Peter Zijlstra]

On Mon, Jul 23, 2018 at 08:09:55AM -0700, Srikar Dronamraju wrote:

> > >   sched/numa: Stop multiple tasks from moving to the cpu at the same time
> 
> This patch has go-ahead from Mel and Rik and no outstanding comments.

I left it out because it's part of the big xchg() mess.

In particular:

+       if (xchg(&rq->numa_migrate_on, 1))
+               return;
+
+       if (env->best_cpu != -1) {
+               rq = cpu_rq(env->best_cpu);
+               WRITE_ONCE(rq->numa_migrate_on, 0);
+       }

I'm again confused by clearing numa_migrate_on at this point..

> > >   sched/numa: Updation of scan period need not be in lock
> 
> I didnt see any comments for this apart from an ack from Rik.
> + It thought it was trivial and shouldnt have any side-effect.

Oh, my bad I actually have this one.