From: Vladimir Davydov <vdavydov@parallels.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Dave Hansen <dave@sr71.net>, Michal Hocko <mhocko@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>, Tejun Heo <tj@kernel.org>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch] mm: memcontrol: revert use of root_mem_cgroup res_counter
Date: Fri, 5 Sep 2014 17:55:07 +0400 [thread overview]
Message-ID: <20140905135507.GE25641@esperanza> (raw)
In-Reply-To: <1409921037-21405-1-git-send-email-hannes@cmpxchg.org>
On Fri, Sep 05, 2014 at 08:43:57AM -0400, Johannes Weiner wrote:
> Dave Hansen reports a massive scalability regression in an uncontained
> page fault benchmark with more than 30 concurrent threads, which he
> bisected down to 05b843012335 ("mm: memcontrol: use root_mem_cgroup
> res_counter") and pin-pointed on res_counter spinlock contention.
>
> That change relied on the per-cpu charge caches to mostly swallow the
> res_counter costs, but it's apparent that the caches don't scale yet.
>
> Revert memcg back to bypassing res_counters on the root level in order
> to restore performance for uncontained workloads.
>
> Reported-by: Dave Hansen <dave@sr71.net>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> Tested-by: Dave Hansen <dave.hansen@intel.com>
> Acked-by: Michal Hocko <mhocko@suse.cz>
It's a pity we have to revert this nice cleanup, but seems we can't do
anything better right now. FWIW,
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
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prev parent reply other threads:[~2014-09-05 13:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-05 12:43 [patch] mm: memcontrol: revert use of root_mem_cgroup res_counter Johannes Weiner
2014-09-05 13:55 ` Vladimir Davydov [this message]
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