Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932302AbaGaJBv (ORCPT ); Thu, 31 Jul 2014 05:01:51 -0400 Received: from mga09.intel.com ([134.134.136.24]:56507 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932239AbaGaJBu (ORCPT ); Thu, 31 Jul 2014 05:01:50 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,770,1400050800"; d="scan'208";a="581611877" Date: Thu, 31 Jul 2014 17:01:30 +0800 From: Aaron Lu To: Mel Gorman Cc: Stephen Rothwell , LKML , lkp@01.org Subject: Re: [LKP] [mm] b72fd1470c9: -41.7% perf-profile.cpu-cycles.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_current.__page_cache_alloc.pagecache_get_page Message-ID: <20140731090130.GB23367@aaronlu.sh.intel.com> References: <20140731055035.GB19742@aaronlu.sh.intel.com> <20140731084832.GP10819@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140731084832.GP10819@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 31, 2014 at 09:48:32AM +0100, Mel Gorman wrote: > On Thu, Jul 31, 2014 at 01:50:35PM +0800, Aaron Lu wrote: > > FYI, we noticed the below changes on > > > > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > > commit b72fd1470c9735f53485d089aa918dc327a86077 ("mm: rearrange zone fields into read-only, page alloc, statistics and page reclaim lines") > > > > test case: lkp-st02/dd-write/5m-11HDD-JBOD-cfq-xfs-10dd > > > > e28c951ff01a805 b72fd1470c9735f53485d089a > > --------------- ------------------------- > > 1.06 ~ 6% -41.7% 0.62 ~ 3% TOTAL perf-profile.cpu-cycles.get_page_from_freelist.__alloc_pages_nodemask.alloc_pages_current.__page_cache_alloc.pagecache_get_page > > 1.34 ~ 2% -19.8% 1.07 ~ 2% TOTAL perf-profile.cpu-cycles.__block_write_begin.xfs_vm_write_begin.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter > > 1.19 ~ 5% -12.1% 1.05 ~ 4% TOTAL perf-profile.cpu-cycles.copy_from_user_atomic_iovec.iov_iter_copy_from_user_atomic.generic_perform_write.xfs_file_buffered_aio_write.xfs_file_write_iter > > 2.78 ~ 1% -16.3% 2.32 ~ 4% TOTAL perf-profile.cpu-cycles.__clear_user.read_zero.read_zero.vfs_read.sys_read > > 2.96e+09 ~ 4% -5.2% 2.806e+09 ~ 0% TOTAL perf-stat.cache-misses > > 3.86e+12 ~ 5% -5.2% 3.658e+12 ~ 1% TOTAL perf-stat.ref-cycles > > > > Legend: > > ~XX% - stddev percent > > [+-]XX% - change percent > > > > I'm not exactly sure what I'm reading here. I think it is reporting on cpu > cycles and cache misses used in various kernel functions. It's not clear what > the units are but it looks like percentages of overall cycles spent in the > reported functions. That may or may not be good depending on whether there > is a higher cost elsewhere pushing the percentages down but that detail > is not in the report. It looks like this is reporting that fewer clock > cycles are being spent and incurring fewer cache misses. What is the problem? LKP does not report problems only, it will also report commits that make things better :-) >From the perf-stat.cache-misses, I think it is indicating your commit does something for good. Thanks, Aaron -- 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/