Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On ke, 2017-05-10 at 12:43 +0200, Andrea Arcangeli wrote:
> It works for me too. I'm running my workstation also with
> synchronize_rcu removed from i915_gem_shrink_all in addition to the
> above. Isn't the oom method invoked from reclaim context too? As far
> as I can tell synchronize_rcu can end up throttling on a background
> synchronize_rcu_expedited(), so it might end up in the same issue
> unless removed too.

Thanks for testing and spotting my bad grepping, I'll add your T-b and
s
end v3.

Regards, Joonas

> Tested-by: Andrea Arcangeli <aarcange@redhat.com>
> 
> (I can't reproduce the lockups 100% of the time, but they never
> happened again with this patch and I happened to run the load that
> reproduces them a couple of times already with v4.11 and this patch
> applied)
> 
> It's also certainly improving performance by removing the
> synchronize_rcu_expedited from the _count methods where it was useless
> (in addition to unsafe).
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation