From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 675596B00C7 for ; Tue, 9 Mar 2010 20:37:06 -0500 (EST) Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [202.81.31.246]) by e23smtp09.au.ibm.com (8.14.3/8.13.1) with ESMTP id o2A1b1BD016160 for ; Wed, 10 Mar 2010 12:37:01 +1100 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o2A1VItX1007796 for ; Wed, 10 Mar 2010 12:31:19 +1100 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o2A1axKC003772 for ; Wed, 10 Mar 2010 12:37:00 +1100 Date: Wed, 10 Mar 2010 07:06:57 +0530 From: Balbir Singh Subject: Re: [PATCH -mmotm 0/5] memcg: per cgroup dirty limit (v6) Message-ID: <20100310013657.GO3073@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <1268175636-4673-1-git-send-email-arighi@develer.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1268175636-4673-1-git-send-email-arighi@develer.com> Sender: owner-linux-mm@kvack.org To: Andrea Righi Cc: KAMEZAWA Hiroyuki , Daisuke Nishimura , Vivek Goyal , Peter Zijlstra , Trond Myklebust , Suleiman Souhlal , Greg Thelen , "Kirill A. Shutemov" , Andrew Morton , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: * Andrea Righi [2010-03-10 00:00:31]: > Control the maximum amount of dirty pages a cgroup can have at any given time. > > Per cgroup dirty limit is like fixing the max amount of dirty (hard to reclaim) > page cache used by any cgroup. So, in case of multiple cgroup writers, they > will not be able to consume more than their designated share of dirty pages and > will be forced to perform write-out if they cross that limit. > > The overall design is the following: > > - account dirty pages per cgroup > - limit the number of dirty pages via memory.dirty_ratio / memory.dirty_bytes > and memory.dirty_background_ratio / memory.dirty_background_bytes in > cgroupfs > - start to write-out (background or actively) when the cgroup limits are > exceeded > > This feature is supposed to be strictly connected to any underlying IO > controller implementation, so we can stop increasing dirty pages in VM layer > and enforce a write-out before any cgroup will consume the global amount of > dirty pages defined by the /proc/sys/vm/dirty_ratio|dirty_bytes and > /proc/sys/vm/dirty_background_ratio|dirty_background_bytes limits. > > Changelog (v5 -> v6) > ~~~~~~~~~~~~~~~~~~~~~~ > * always disable/enable IRQs at lock/unlock_page_cgroup(): this allows to drop > the previous complicated locking scheme in favor of a simpler locking, even > if this obviously adds some overhead (see results below) > * drop FUSE and NILFS2 dirty pages accounting for now (this depends on > charging bounce pages per cgroup) > > Results > ~~~~~~~ > I ran some tests using a kernel build (2.6.33 x86_64_defconfig) on a > Intel Core 2 @ 1.2GHz as testcase using different kernels: > - mmotm "vanilla" > - mmotm with cgroup-dirty-memory using the previous "complex" locking scheme > (my previous patchset + the fixes reported by Kame-san and Daisuke-san) > - mmotm with cgroup-dirty-memory using the simple locking scheme > (lock_page_cgroup() with IRQs disabled) > > Following the results: > > - mmotm "vanilla", root cgroup: 11m51.983s > - mmotm "vanilla", child cgroup: 11m56.596s > > > - mmotm, "complex" locking scheme, root cgroup: 11m53.037s > - mmotm, "complex" locking scheme, child cgroup: 11m57.896s > > - mmotm, lock_page_cgroup+irq_disabled, root cgroup: 12m5.499s > - mmotm, lock_page_cgroup+irq_disabled, child cgroup: 12m9.920s > This is a cause for big concern, any chance you could test this on a large system. I am concerned about root overhead the most. -- Three Cheers, Balbir -- 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