From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757176AbYD2N5U (ORCPT ); Tue, 29 Apr 2008 09:57:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751613AbYD2N5M (ORCPT ); Tue, 29 Apr 2008 09:57:12 -0400 Received: from extu-mxob-2.symantec.com ([216.10.194.135]:35107 "EHLO extu-mxob-2.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750981AbYD2N5M (ORCPT ); Tue, 29 Apr 2008 09:57:12 -0400 Date: Tue, 29 Apr 2008 14:57:15 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.site To: Ross Biro cc: linux-mm@kvack.org, lkml Subject: Re: Page Faults slower in 2.6.25-rc9 than 2.6.23 In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 29 Apr 2008, Ross Biro wrote: > I don't know if this has been noticed before. I was benchmarking my > page table relocation code and I noticed that on 2.6.25-rc9 page > faults take 10% more time than on 2.6.22. This is using lmbench > running on an intel x86_64 system. The good news is that the page > table relocation code now only adds a 1.6% slow down to page faults. Do you have CONFIG_CGROUP_MEM_RES_CTLR=y in 2.6.25? That added about 20% to my lmbench "Page Fault" tests (with adverse effect on several others e.g. the fork, exec, sh group). Try the same kernel with boot option "cgroup_disable=memory", that should recoup most (but not quite all) of the slowdown; or rebuild with n to CGROUP_MEM_RES_CTLR. But your "Mmap Latency" went up 425% ?? Hugh > > Ross > > 2.6.25-rc9: > > File & VM system latencies in microseconds - smaller is better > ------------------------------------------------------------------------------- > Host OS 0K File 10K File Mmap Prot Page 100fd > Create Delete Create Delete Latency Fault Fault selct > --------- ------------- ------ ------ ------ ------ ------- ----- ------- ----- > ipnn2 Linux 2.6.25- 13.9 7.6111 103.4 9.7453 926.0 0.711 2.14250 2.552 > ipnn2 Linux 2.6.25- 13.7 7.6243 310.7 9.6574 932.0 0.750 2.15970 2.555 > ipnn2 Linux 2.6.25- 13.9 7.6831 192.5 10.0 927.0 0.760 2.21310 2.553 > ipnn2 Linux 2.6.25- 13.9 7.5739 98.4 9.5330 927.0 0.703 2.17610 2.554 > ipnn2 Linux 2.6.25- 14.6 7.6429 39.1 10.8 935.0 0.763 2.17250 2.552 > ipnn2 Linux 2.6.25- 14.1 7.8777 129.8 9.9375 930.0 0.782 2.26460 2.559 > ipnn2 Linux 2.6.25- 14.8 7.9639 623.8 8.2042 927.0 0.773 2.21510 2.557 > ipnn2 Linux 2.6.25- 14.4 7.5842 622.3 8.3272 920.0 0.745 2.22210 2.558 > ipnn2 Linux 2.6.25- 14.2 7.6339 45.7 10.2 935.0 0.675 2.23860 2.554 > ipnn2 Linux 2.6.25- 14.1 7.7175 263.7 10.1 929.0 0.762 2.22350 2.556 > ipnn2 Linux 2.6.25- 13.9 8.1230 378.2 9.4343 975.0 0.752 2.25920 2.554 > > > 2.6.23: > File & VM system latencies in microseconds - smaller is better > ------------------------------------------------------------------------------- > Host OS 0K File 10K File Mmap Prot Page 100fd > Create Delete Create Delete Latency Fault Fault selct > --------- ------------- ------ ------ ------ ------ ------- ----- ------- ----- > ipnn2 Linux 2.6.23- 218.0 0.912 1.94010 2.626 > ipnn2 Linux 2.6.23- 219.0 1.095 1.96400 2.597 > ipnn2 Linux 2.6.23- 219.0 0.774 1.96640 2.603 > ipnn2 Linux 2.6.23- 221.0 0.946 1.99950 2.601 > ipnn2 Linux 2.6.23- 219.0 0.902 1.99160 2.733 > ipnn2 Linux 2.6.23- 217.0 0.904 2.04790 2.601 > ipnn2 Linux 2.6.23- 225.0 0.893 1.99620 2.600