From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [RFC] Make the slab allocator observe NUMA policies Date: Mon, 14 Nov 2005 19:44:33 +0100 References: <200511131222.48690.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: <200511141944.33478.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 19:05, Christoph Lameter wrote: > On Sun, 13 Nov 2005, Andi Kleen wrote: > > > On Friday 11 November 2005 18:40, Christoph Lameter wrote: > > > > > Hmm. Thats not easy to do since the slab allocator is managing the pages > > > in terms of the nodes where they are located. The whole thing is geared to > > > first inspect the lists for one node and then expand if no page is > > > available. > > > > Yes, that's fine - as long as it doesn't allocate too many > > pages at one go (which it doesn't) then the interleaving should > > even the allocations out at page level. > > The slab allocator may allocate pages higher orders which need to > be physically continuous. > Any idea how to push this to the page allocation within the slab without > rearchitecting the thing? I believe that's only a small fraction of the allocations, for where the slabs are big enough to be an significant part of the page. Proof: VM breaks down with higher orders. If slab would use them all the time it would break down too. It doesn't. Q.E.D ;-) Also looking at the objsize colum in /proc/slabinfo most slabs are significantly smaller than a page and the higher kmalloc slabs don't have too many objects, so slab shouldn't do this too often. You're right they're a problem, but perhaps they can be just ignored (like if they are <20% of the allocations the inbalance resulting from them might not be too bad) Another way (as a backup option) would be to RR them as higher order pages, but that would need new special code. -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