lkml.org 
[lkml]   [2015]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] mm: use srcu for shrinkers
From
Date
On Wed, 2015-06-17 at 09:47 +0200, Michal Hocko wrote:
> On the other hand using srcu is a neat idea. Shrinkers only need the
> existence guarantee when racing with unregister. Register even shouldn't
> be that interesting because such a shrinker wouldn't have much to
> shrink anyway so we can safely miss it AFAIU. With the srcu read lock
> we can finally get rid of the try_lock. I do not think you need an
> ugly spin_is_locked as the replacement though. We have the existence
> guarantee and that should be sufficient.

So the reason for the spin_is_locked check was that I was concerned
about new reader(s) that come in while doing the registry. Currently
this is forbidden by the trylock and fake-ish retry. But yes, perhaps I
was being over safe and we shouldn't be blockling the reclaim simply
because a shrinker is registering. And it would be cleaner to get rid of
the whole retry idea and just use rcu guarantees.

This is probably a little late in the game to try to push for 4.2, so
I'll send a v2 with any other updates that might come up once the merge
window closes.

Thanks,
Davidlohr



\
 
 \ /
  Last update: 2015-06-18 03:41    [W:0.076 / U:1.768 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site