From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [patch 0/7] cpuset writeback throttling Date: Tue, 4 Nov 2008 14:35:34 -0800 Message-ID: <20081104143534.b5c16147.akpm@linux-foundation.org> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: containers.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?