Re: [tip:sched/core] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine()

[Mel Gorman]

On Wed, May 09, 2018 at 03:58:14AM -0700, Srikar Dronamraju wrote:
> In the other scenario, where wake_affine set p->numa_migrate_preferred to a
> bigger value, the task calls numa_migrate_preferred(),
> numa_migrate_preferred  could be before p->numa_migrate_preferred. In
> such a case, we should have stopped the task from migration.
> However we overwrite p->numa_migrate_preferred and do the
> task_numa_migrate(). Somehow this doesn't seem to achieve what the
> commit intended.
> 
> Or did I misunderstand?
> 

Nope, the logic is broken. While it can be "fixed", the end result adds
complexity for very little gain. I believe the right path for the moment
is a revert and retry at a future date.

Thanks.

-- 
Mel Gorman
SUSE Labs