From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 2.6.17-rc1-mm1 0/6] Migrate-on-fault - Overview Date: Tue, 11 Apr 2006 20:52:49 +0200 References: <1144441108.5198.36.camel@localhost.localdomain> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200604112052.50133.ak@suse.de> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Lee Schermerhorn , linux-mm , ak@suse.com List-ID: On Tuesday 11 April 2006 20:46, Christoph Lameter wrote: > However, if the page is not frequently references then the > effort required to migrate the page was not justified. I have my doubts the whole thing is really worthwhile. It probably would at least need some statistics to only do this for frequent accesses, but I don't know where to put this data. At least it would be a serious research project to figure out a good way to do automatic migration. From what I was told by people who tried this (e.g. in Irix) it is really hard and didn't turn out to be a win for them. The better way is to just provide the infrastructure and let batch managers or program itselves take care of migration. That was the whole idea behind NUMA API - some problems are too hard to figure out automatically by the kernel, so allow the user or application to give it a hand. And frankly the defaults we have currently are not that bad, perhaps with some small tweaks (e.g. i'm still liking the idea of interleaving file cache by default) -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