From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id 013F46B0253 for ; Sat, 14 Jan 2017 08:34:08 -0500 (EST) Received: by mail-lf0-f72.google.com with SMTP id x1so31492995lff.6 for ; Sat, 14 Jan 2017 05:34:07 -0800 (PST) Received: from smtp24.mail.ru (smtp24.mail.ru. [94.100.181.179]) by mx.google.com with ESMTPS id a63si9835747lfe.376.2017.01.14.05.34.06 for (version=TLS1 cipher=AES128-SHA bits=128/128); Sat, 14 Jan 2017 05:34:06 -0800 (PST) Date: Sat, 14 Jan 2017 16:33:56 +0300 From: Vladimir Davydov Subject: Re: [PATCH 5/9] slab: link memcg kmem_caches on their associated memory cgroup Message-ID: <20170114133356.GD2668@esperanza> References: <20170114055449.11044-1-tj@kernel.org> <20170114055449.11044-6-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170114055449.11044-6-tj@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, jsvana@fb.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, kernel-team@fb.com On Sat, Jan 14, 2017 at 12:54:45AM -0500, Tejun Heo wrote: > With kmem cgroup support enabled, kmem_caches can be created and > destroyed frequently and a great number of near empty kmem_caches can > accumulate if there are a lot of transient cgroups and the system is > not under memory pressure. When memory reclaim starts under such > conditions, it can lead to consecutive deactivation and destruction of > many kmem_caches, easily hundreds of thousands on moderately large > systems, exposing scalability issues in the current slab management > code. This is one of the patches to address the issue. > > While a memcg kmem_cache is listed on its root cache's ->children > list, there is no direct way to iterate all kmem_caches which are > assocaited with a memory cgroup. The only way to iterate them is > walking all caches while filtering out caches which don't match, which > would be most of them. > > This makes memcg destruction operations O(N^2) where N is the total > number of slab caches which can be huge. This combined with the > synchronous RCU operations can tie up a CPU and affect the whole > machine for many hours when memory reclaim triggers offlining and > destruction of the stale memcgs. > > This patch adds mem_cgroup->kmem_caches list which goes through > memcg_cache_params->kmem_caches_node of all kmem_caches which are > associated with the memcg. All memcg specific iterations, including > stat file access, are updated to use the new list instead. > > Signed-off-by: Tejun Heo > Reported-by: Jay Vana > Cc: Vladimir Davydov > Cc: Christoph Lameter > Cc: Pekka Enberg > Cc: David Rientjes > Cc: Joonsoo Kim > Cc: Andrew Morton Acked-by: Vladimir Davydov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org