From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [RFC] Make the slab allocator observe NUMA policies Date: Tue, 15 Nov 2005 04:34:14 +0100 References: <200511141944.33478.ak@suse.de> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200511150434.15094.ak@suse.de> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: steiner@sgi.com, linux-mm@kvack.org, alokk@calsoftinc.com List-ID: On Monday 14 November 2005 20:08, Christoph Lameter wrote: > The slab allocator is designed in such a way that it needs to know the > node for the allocation before it does its work. This is because the > nodelists are per node since 2.6.14. You wanted to do the policy > application on the back end so after all the work is done (presumably > for the current node) and after the node specific lists have been > examined. Policy application at that point may find that another > node than the current node was desired and the whole thing has to be > redone for the other node. This will significantly negatively impact > the performance of the slab allocator in particular if the current node > is is unlikely to be chosen for the memory policy. > > I have thought about various ways to modify kmem_getpages() but these do > not fit into the basic current concept of the slab allocator. The > proposed method is the cleanest approach that I can think of. I'd be glad > if you could come up with something different but AFAIK simply moving the > policy application down in the slab allocator does not work. I haven't checked all the details, but why can't it be done at the cache_grow layer? (that's already a slow path) If it's not possible to do it in the slow path I would say the design is incompatible with interleaving then. Better not do it then than doing it wrong. -Andi -- 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