From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754112AbXDUEAF (ORCPT ); Sat, 21 Apr 2007 00:00:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754111AbXDUEAF (ORCPT ); Sat, 21 Apr 2007 00:00:05 -0400 Received: from mx1.redhat.com ([66.187.233.31]:60676 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754112AbXDUEAD (ORCPT ); Sat, 21 Apr 2007 00:00:03 -0400 Message-ID: <46298BE8.8020900@redhat.com> Date: Fri, 20 Apr 2007 23:58:32 -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: Andrew Morton , linux-kernel , linux-mm , shak Subject: Re: [PATCH] lazy freeing of memory through MADV_FREE References: <46247427.6000902@redhat.com> <20070420135715.f6e8e091.akpm@linux-foundation.org> <462932BE.4020005@redhat.com> <20070420150618.179d31a4.akpm@linux-foundation.org> <4629524C.5040302@redhat.com> <46295F59.8000506@cosmosbay.com> In-Reply-To: <46295F59.8000506@cosmosbay.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Eric Dumazet wrote: > Rik van Riel a écrit : >> Andrew Morton wrote: >>> On Fri, 20 Apr 2007 17:38:06 -0400 >>> Rik van Riel wrote: >>> >>>> Andrew Morton wrote: >>>> >>>>> I've also merged Nick's "mm: madvise avoid exclusive mmap_sem". >>>>> >>>>> - Nick's patch also will help this problem. It could be that your >>>>> patch >>>>> no longer offers a 2x speedup when combined with Nick's patch. >>>>> >>>>> It could well be that the combination of the two is even better, >>>>> but it >>>>> would be nice to firm that up a bit. >>>> I'll test that. >>> >>> Thanks. >> >> Well, good news. >> >> It turns out that Nick's patch does not improve peak >> performance much, but it does prevent the decline when >> running with 16 threads on my quad core CPU! >> >> We _definately_ want both patches, there's a huge benefit >> in having them both. >> >> Here are the transactions/seconds for each combination: >> >> vanilla new glibc madv_free kernel madv_free + mmap_sem >> threads >> >> 1 610 609 596 545 > > 545 tps versus 610 tps for one thread ? It seems quite bad, no ? > > Could you please find an explanation for this ? I have no idea why this happens. Especially the last one, going from a write lock to a read lock on the mmap_sem should not make ANY difference whatsoever since we're running single threaded! >> 2 1032 1136 1196 1200 >> 4 1070 1128 2014 2024 >> 8 1000 1088 1665 2087 >> 16 779 1073 1310 1999 Performance with 2 database threads is way better though, and performance with 4 or more threads more than doubles... If you have an explanation on why single threaded performance went down a little on my quad core system, please let me know. Does performance suffer at all on a real UP system? -- 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. From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <46298BE8.8020900@redhat.com> Date: Fri, 20 Apr 2007 23:58:32 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] lazy freeing of memory through MADV_FREE References: <46247427.6000902@redhat.com> <20070420135715.f6e8e091.akpm@linux-foundation.org> <462932BE.4020005@redhat.com> <20070420150618.179d31a4.akpm@linux-foundation.org> <4629524C.5040302@redhat.com> <46295F59.8000506@cosmosbay.com> In-Reply-To: <46295F59.8000506@cosmosbay.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Return-Path: To: Eric Dumazet Cc: Andrew Morton , linux-kernel , linux-mm , shak List-ID: Eric Dumazet wrote: > Rik van Riel a A(C)crit : >> Andrew Morton wrote: >>> On Fri, 20 Apr 2007 17:38:06 -0400 >>> Rik van Riel wrote: >>> >>>> Andrew Morton wrote: >>>> >>>>> I've also merged Nick's "mm: madvise avoid exclusive mmap_sem". >>>>> >>>>> - Nick's patch also will help this problem. It could be that your >>>>> patch >>>>> no longer offers a 2x speedup when combined with Nick's patch. >>>>> >>>>> It could well be that the combination of the two is even better, >>>>> but it >>>>> would be nice to firm that up a bit. >>>> I'll test that. >>> >>> Thanks. >> >> Well, good news. >> >> It turns out that Nick's patch does not improve peak >> performance much, but it does prevent the decline when >> running with 16 threads on my quad core CPU! >> >> We _definately_ want both patches, there's a huge benefit >> in having them both. >> >> Here are the transactions/seconds for each combination: >> >> vanilla new glibc madv_free kernel madv_free + mmap_sem >> threads >> >> 1 610 609 596 545 > > 545 tps versus 610 tps for one thread ? It seems quite bad, no ? > > Could you please find an explanation for this ? I have no idea why this happens. Especially the last one, going from a write lock to a read lock on the mmap_sem should not make ANY difference whatsoever since we're running single threaded! >> 2 1032 1136 1196 1200 >> 4 1070 1128 2014 2024 >> 8 1000 1088 1665 2087 >> 16 779 1073 1310 1999 Performance with 2 database threads is way better though, and performance with 4 or more threads more than doubles... If you have an explanation on why single threaded performance went down a little on my quad core system, please let me know. Does performance suffer at all on a real UP system? -- 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. -- 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