Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756836AbXELFvQ (ORCPT ); Sat, 12 May 2007 01:51:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754370AbXELFvG (ORCPT ); Sat, 12 May 2007 01:51:06 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:59995 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750930AbXELFvD (ORCPT ); Sat, 12 May 2007 01:51:03 -0400 Date: Fri, 11 May 2007 22:51:11 -0700 From: Paul Jackson To: Con Kolivas Cc: nickpiggin@yahoo.com.au, ray-lk@madrabbit.org, mingo@elte.hu, ck@vds.kolivas.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm: swap prefetch improvements Message-Id: <20070511225111.fee05bb9.pj@sgi.com> In-Reply-To: <200705121516.00070.kernel@kolivas.org> References: <20070430162007.ad46e153.akpm@linux-foundation.org> <200705121446.04191.kernel@kolivas.org> <20070511220314.f7af1d31.pj@sgi.com> <200705121516.00070.kernel@kolivas.org> Organization: SGI X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.3; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1546 Lines: 35 Con wrote: > Hmm I'm not really sure what it takes to make it cpuset aware; > ... > It is numa aware to some degree. It stores the node id and when it starts > prefetching it only prefetches to nodes that are suitable for prefetching to > ... > It would be absolutely trivial to add a check for 'number_of_cpusets' <= 1 > in the prefetch_enabled() function. Would you like that? Hmmm ... it seems that we shadow boxing here ... trying to pick a solution to solve a problem when we aren't even sure we have a problem, much less what the problem is. That does not usually lead to the right path. Could you put some more effort into characterizing what problems can arise if one has prefetch and cpusets active at the same time? My first wild guess is that the only incompatibility would have been that prefetch might mess up NUMA placement (get pages on wrong nodes), which it seems you have tried to address in your current patches. So it would not surprise me if there was no problem here. We may just have to lean on Nick some more, if he is the only one who understands what the problem is, to try again to explain it to us. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/