From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756126Ab0FAQU2 (ORCPT ); Tue, 1 Jun 2010 12:20:28 -0400 Received: from one.firstfloor.org ([213.235.205.2]:35428 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756012Ab0FAQU1 (ORCPT ); Tue, 1 Jun 2010 12:20:27 -0400 Date: Tue, 1 Jun 2010 18:20:25 +0200 From: Andi Kleen To: Nick Piggin Cc: Andi Kleen , Linus Torvalds , Ingo Molnar , Peter Zijlstra , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lee@firstfloor.org, Schermerh@firstfloor.org Subject: Re: [rfc] forked kernel task and mm structures imbalanced on NUMA Message-ID: <20100601162024.GC30556@basil.fritz.box> References: <20100601073343.GQ9453@laptop> <87wruiycsl.fsf@basil.nowhere.org> <20100601155943.GA9453@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100601155943.GA9453@laptop> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 02, 2010 at 01:59:43AM +1000, Nick Piggin wrote: > On Tue, Jun 01, 2010 at 05:48:10PM +0200, Andi Kleen wrote: > > Nick Piggin writes: > > > > > This isn't really a new problem, and I don't know how important it is, > > > but I recently came across it again when doing some aim7 testing with > > > huge numbers of tasks. > > > > Seems reasonable. Of course you need to at least > > save/restore the old CPU policy, and use a subset of it. > > The mpolicy? My patch does that (mpol_prefer_cpu_start/end). The real > problem is that it can actually violate the parent's mempolicy. For > example MPOL_BIND and cpus_allowed set on a node outside the mempolicy. I don't see where you store 'old', but maybe I missed it. > > slightly more difficult. The advantage would be that on multiple > > migrations it would follow. And it would be a bit slower for > > the initial case. > > Migrate what on touch? Talking mainly about kernel memory structures, > task_struct, mm, vmas, page tables, kernel stack, etc. Migrate task_struct, mm, vmas, page tables, kernel stack on reasonable touch. As long as they are not shared it shouldn't be too difficult. -Andi -- ak@linux.intel.com -- Speaking for myself only.