From: Michal Hocko <mhocko@suse.cz>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave@sr71.net>, Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>, Tejun Heo <tj@kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Vladimir Davydov <vdavydov@parallels.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: regression caused by cgroups optimization in 3.17-rc2
Date: Fri, 5 Sep 2014 11:28:41 +0200 [thread overview]
Message-ID: <20140905092841.GD26243@dhcp22.suse.cz> (raw)
In-Reply-To: <5408ED7A.5010908@intel.com>
On Thu 04-09-14 15:53:46, Dave Hansen wrote:
> On 09/04/2014 01:27 PM, Dave Hansen wrote:
> > On 09/04/2014 07:27 AM, Michal Hocko wrote:
> >> Ouch. free_pages_and_swap_cache completely kills the uncharge batching
> >> because it reduces it to PAGEVEC_SIZE batches.
> >>
> >> I think we really do not need PAGEVEC_SIZE batching anymore. We are
> >> already batching on tlb_gather layer. That one is limited so I think
> >> the below should be safe but I have to think about this some more. There
> >> is a risk of prolonged lru_lock wait times but the number of pages is
> >> limited to 10k and the heavy work is done outside of the lock. If this
> >> is really a problem then we can tear LRU part and the actual
> >> freeing/uncharging into a separate functions in this path.
> >>
> >> Could you test with this half baked patch, please? I didn't get to test
> >> it myself unfortunately.
> >
> > 3.16 settled out at about 11.5M faults/sec before the regression. This
> > patch gets it back up to about 10.5M, which is good. The top spinlock
> > contention in the kernel is still from the resource counter code via
> > mem_cgroup_commit_charge(), though.
> >
> > I'm running Johannes' patch now.
>
> This looks pretty good. The area where it plateaus (above 80 threads
> where hyperthreading kicks in) might be a bit slower than it was in
> 3.16, but that could easily be from other things.
Good news indeed. But I think it would be safer to apply Johannes'
revert for now. Both changes are still worth having anyway because they
have potential to improve memcg case.
> > https://www.sr71.net/~dave/intel/bb.html?1=3.16.0-rc4-g67b9d76/&2=3.17.0-rc3-g57b252f
>
> Feel free to add my Tested-by:
Thanks a lot! I have posted another patch which reduces the batching for
LRU handling because this would be too risky. So I haven't added your
Tested-by yet.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2014-09-05 9:28 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-02 19:05 Dave Hansen
2014-09-02 20:18 ` Dave Hansen
2014-09-02 20:57 ` Dave Hansen
2014-09-04 14:27 ` Michal Hocko
2014-09-04 20:27 ` Dave Hansen
2014-09-04 22:53 ` Dave Hansen
2014-09-05 9:28 ` Michal Hocko [this message]
2014-09-05 9:25 ` Michal Hocko
2014-09-05 14:47 ` Johannes Weiner
2014-09-05 15:39 ` Michal Hocko
2014-09-10 16:29 ` Michal Hocko
2014-09-10 16:57 ` Dave Hansen
2014-09-10 17:05 ` Michal Hocko
2014-09-05 12:35 ` Johannes Weiner
2014-09-08 15:47 ` Dave Hansen
2014-09-09 14:50 ` Johannes Weiner
2014-09-09 18:23 ` Dave Hansen
2014-09-02 22:18 ` Johannes Weiner
2014-09-02 22:36 ` Dave Hansen
2014-09-03 0:10 ` Johannes Weiner
2014-09-03 0:20 ` Linus Torvalds
2014-09-03 1:33 ` Johannes Weiner
2014-09-03 3:15 ` Dave Hansen
2014-09-03 0:30 ` Dave Hansen
2014-09-04 15:08 ` Johannes Weiner
2014-09-04 20:50 ` Dave Hansen
2014-09-05 8:04 ` Michal Hocko
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