From: Johannes Weiner <hannes@cmpxchg.org>
To: Dave Hansen <dave@sr71.net>
Cc: Michal Hocko <mhocko@suse.com>, Hugh Dickins <hughd@google.com>,
Tejun Heo <tj@kernel.org>,
Vladimir Davydov <vdavydov@parallels.com>,
Linus Torvalds <torvalds@linuxfoundation.org>,
Andrew Morton <akpm@linuxfoundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>
Subject: Re: regression caused by cgroups optimization in 3.17-rc2
Date: Thu, 4 Sep 2014 11:08:46 -0400 [thread overview]
Message-ID: <20140904150846.GA10794@cmpxchg.org> (raw)
In-Reply-To: <5406612E.8040802@sr71.net>
On Tue, Sep 02, 2014 at 05:30:38PM -0700, Dave Hansen wrote:
> On 09/02/2014 05:10 PM, Johannes Weiner wrote:
> > On Tue, Sep 02, 2014 at 03:36:29PM -0700, Dave Hansen wrote:
> >> On 09/02/2014 03:18 PM, Johannes Weiner wrote:
> >>> Accounting new pages is buffered through per-cpu caches, but taking
> >>> them off the counters on free is not, so I'm guessing that above a
> >>> certain allocation rate the cost of locking and changing the counters
> >>> takes over. Is there a chance you could profile this to see if locks
> >>> and res_counter-related operations show up?
> >>
> >> It looks pretty much the same, although it might have equalized the
> >> charge and uncharge sides a bit. Full 'perf top' output attached.
> >
> > That looks like a partial profile, where did the page allocator, page
> > zeroing etc. go? Because the distribution among these listed symbols
> > doesn't seem all that crazy:
>
> Perf was only outputting the top 20 functions. Believe it or not, page
> zeroing and the rest of the allocator path wasn't even in the path of
> the top 20 functions because there is so much lock contention.
>
> Here's a longer run of 'perf top' along with the top 100 functions:
>
> http://www.sr71.net/~dave/intel/perf-top-1409702817.txt.gz
>
> you can at least see copy_page_rep in there.
Thanks for the clarification, that is truly horrible. Does the
following revert restore performance in your case?
---
next prev parent reply other threads:[~2014-09-04 15:09 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-02 19:05 regression caused by cgroups optimization in 3.17-rc2 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
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 [this message]
2014-09-04 20:50 ` Dave Hansen
2014-09-05 8:04 ` Michal Hocko
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