From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 16 Sep 2006 16:10:31 -0700 From: Andrew Morton Subject: Re: [PATCH] GFP_THISNODE for the slab allocator Message-Id: <20060916161031.4b7c2470.akpm@osdl.org> In-Reply-To: <20060916145117.9b44786d.pj@sgi.com> References: <20060914220011.2be9100a.akpm@osdl.org> <20060914234926.9b58fd77.pj@sgi.com> <20060915002325.bffe27d1.akpm@osdl.org> <20060916044847.99802d21.pj@sgi.com> <20060916083825.ba88eee8.akpm@osdl.org> <20060916145117.9b44786d.pj@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Paul Jackson Cc: clameter@sgi.com, linux-mm@kvack.org, rientjes@google.com List-ID: On Sat, 16 Sep 2006 14:51:17 -0700 Paul Jackson wrote: > Andrew wrote: > > Pretty much all loads? If you haven't consumed most of the "container"'s > > memory then you have overprovisioned its size. > > Not so on real NUMA boxes. I meant pretty much all loads when employing this trick of reusing the NUMA code for containerisation. > If you configure your system so that > you are having to go a long way off-node for much of your memory, > then your performance is screwed. > > No one in their right mind would run a memory hog that eats 40 nodes > of memory and a kernel build both in the same 60 node, small CPU > count cpuset on a real NUMA box. > > The primary motivation for cpusets is to improve memory locality on > NUMA boxes. You're using fake numa and cpusets to simulate destroying > memory locality. > > On a real 64 node NUMA box, there would be 64 differently sorted > zonelists, each one centered on a different node. The kernel build > would be running on different CPUs, associated with different nodes > than the memory hog, and it would be using zonelists that had the > unloaded (still has free memory) nodes at the front the list. > > Aha - maybe this is the problem - the fake numa stuff is missing the > properly sorted zone lists. I don't see how any of this could help. If one has a memory container which is constructed from 50 zones, that linear search is just going to do a lot of linear searching when the container approaches anything like fullness. It could well be a single CPU machine... -- 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