lkml.org 
[lkml]   [2016]   [Jul]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Severe performance regression w/ 4.4+ on Android due to cgroup locking changes
On 07/14, John Stultz wrote:
>
> I'm not supposed to be applying this on-top of
> Paul's change, right?

Right, unless I am totally confused,

> > Just in case, could you try the patch below? Of course, without other
> > optimizations from Peter, this change makes cgroup_threadgroup_rwsem
> > much worse than a plain rw_semaphore.
> >
> > Oleg.
> >
> > --- x/kernel/cgroup.c
> > +++ x/kernel/cgroup.c
> > @@ -5605,6 +5605,8 @@ int __init cgroup_init(void)
> > BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
> > BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
> >
> > + rcu_sync_enter(&cgroup_threadgroup_rwsem.rss);
> > +
>
>
> So adding this does make a huge difference ontop of Peter's patch.

Ah, sorry for confusion. I meant, you could try this one-liner without
any other changes.

But we will need the "slow mode optimization" part from Peter's patch
anyway, otherwise percpu_rw_semaphore simply makes no sense for
cgroup_threadgroup_rwsem.

Oleg.

\
 
 \ /
  Last update: 2016-07-14 20:21    [W:0.084 / U:43.692 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site