From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946098AbXDEIcg (ORCPT ); Thu, 5 Apr 2007 04:32:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946099AbXDEIcg (ORCPT ); Thu, 5 Apr 2007 04:32:36 -0400 Received: from mx1.redhat.com ([66.187.233.31]:47295 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946098AbXDEIce (ORCPT ); Thu, 5 Apr 2007 04:32:34 -0400 Message-ID: <4614B3FB.2090405@redhat.com> Date: Thu, 05 Apr 2007 04:31:55 -0400 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 1.5.0.7 (X11/20061008) MIME-Version: 1.0 To: Eric Dumazet CC: Jakub Jelinek , Ulrich Drepper , Andrew Morton , Andi Kleen , Linux Kernel , linux-mm@kvack.org, Hugh Dickins Subject: Re: missing madvise functionality References: <46128051.9000609@redhat.com> <46128CC2.9090809@redhat.com> <20070403172841.GB23689@one.firstfloor.org> <20070403125903.3e8577f4.akpm@linux-foundation.org> <4612B645.7030902@redhat.com> <20070403202937.GE355@devserv.devel.redhat.com> <4614A5CC.5080508@redhat.com> <20070405100848.db97d835.dada1@cosmosbay.com> In-Reply-To: <20070405100848.db97d835.dada1@cosmosbay.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Eric Dumazet wrote: > Could you please add this patch and see if it helps on your machine ? > > [PATCH] VM : mm_struct's mmap_cache should be close to mmap_sem > > Avoids cache line dirtying I could, but I already know it's not going to help much. How do I know this? I already have 66% idle time when running with my patch (and without Nick Piggin's patch to take the mmap_sem for reading only). Interestingly, despite the idle time increasing from 10% to 66%, throughput triples... Saving some CPU time will probably only increase the idle time, I see no reason your patch would reduce contention and increase throughput. I'm not saying your patch doesn't make sense - it probably does. I just suspect it would have zero impact on this particular scenario, because of the already huge idle time. -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic.