From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756819AbYKDWgc (ORCPT ); Tue, 4 Nov 2008 17:36:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756368AbYKDWgR (ORCPT ); Tue, 4 Nov 2008 17:36:17 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:60615 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755696AbYKDWgQ (ORCPT ); Tue, 4 Nov 2008 17:36:16 -0500 Date: Tue, 4 Nov 2008 14:35:34 -0800 From: Andrew Morton To: Christoph Lameter Cc: peterz@infradead.org, rientjes@google.com, npiggin@suse.de, menage@google.com, dfults@sgi.com, linux-kernel@vger.kernel.org, containers@lists.osdl.org Subject: Re: [patch 0/7] cpuset writeback throttling Message-Id: <20081104143534.b5c16147.akpm@linux-foundation.org> In-Reply-To: References: <20081104124753.fb1dde5a.akpm@linux-foundation.org> <1225831988.7803.1939.camel@twins> <20081104131637.68fbe055.akpm@linux-foundation.org> <1225833710.7803.1993.camel@twins> <20081104135004.f1717fcf.akpm@linux-foundation.org> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Nov 2008 16:17:52 -0600 (CST) Christoph Lameter wrote: > On Tue, 4 Nov 2008, Andrew Morton wrote: > > > What are the alternatives here? What do we need to do to make > > throttling a per-memcg thing? > > Add statistics to the memcg lru and then you need some kind of sets of > memcgs that are represented by bitmaps or so attached to an inode. > > > The patchset is badly misnamed, btw. It doesn't throttle writeback - > > in fact several people are working on IO bandwidth controllers and > > calling this thing "writeback throttling" risks confusion. > > It is limiting dirty pages and throttling the dirty rate of applications > in a NUMA system (same procedure as we do in non NUMA). The excessive > dirtying without this patchset can cause OOMs to occur on NUMA systems. yup. To fix this with a memcg-based throttling, the operator would need to be able to create memcg's which have pages only from particular nodes. (That's a bit indirect relative to what they want to do, but is presumably workable). But do we even have that capability now?