From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753556AbdARVJ1 (ORCPT ); Wed, 18 Jan 2017 16:09:27 -0500 Received: from mail-pg0-f68.google.com ([74.125.83.68]:36011 "EHLO mail-pg0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752094AbdARVJY (ORCPT ); Wed, 18 Jan 2017 16:09:24 -0500 Date: Wed, 18 Jan 2017 13:01:15 -0800 From: Tejun Heo To: Joonsoo Kim Cc: vdavydov.dev@gmail.com, cl@linux.com, penberg@kernel.org, rientjes@google.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 Subject: Re: [PATCHSET v2] slab: make memcg slab destruction scalable Message-ID: <20170118210115.GE9171@mtj.duckdns.org> References: <20170114184834.8658-1-tj@kernel.org> <20170117001256.GB25218@js1304-P5Q-DELUXE> <20170117164913.GB28948@mtj.duckdns.org> <20170118075448.GA1255@js1304-P5Q-DELUXE> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170118075448.GA1255@js1304-P5Q-DELUXE> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Jan 18, 2017 at 04:54:48PM +0900, Joonsoo Kim wrote: > That problem is caused by slow release path and then contention on the > slab_mutex. With an ordered workqueue, kworker would not be created a > lot but it can be possible that a lot of work items to create a new > cache for memcg is pending for a long time due to slow release path. How many work items are pending and how many workers are on them shouldn't affect the actual completion time that much when most of them are serialized by a mutex. Anyways, this patchset moves all the slow parts out of slab_mutex, so none of this is a problem anymore. > Your patchset replaces optimization for release path so it's better to > check that the work isn't pending for a long time in above workload. Yeap, it seems to work fine. Thanks. -- tejun