Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754212Ab3IQXWT (ORCPT ); Tue, 17 Sep 2013 19:22:19 -0400 Received: from mga11.intel.com ([192.55.52.93]:20538 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753457Ab3IQXWS (ORCPT ); Tue, 17 Sep 2013 19:22:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.90,926,1371106800"; d="scan'208";a="397263557" Date: Wed, 18 Sep 2013 07:22:14 +0800 From: Fengguang Wu To: Peter Hurley Cc: Greg KH , LKML , lkp@01.org, Tejun Heo Subject: Re: increased vmap_area_lock contentions on "n_tty: Move buffers into n_tty_data" Message-ID: <20130917232214.GA11390@localhost> References: <20130913005133.GA32479@localhost> <20130913010936.GA1291@localhost> <5238767D.1080606@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5238767D.1080606@hurleysoftware.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3317 Lines: 86 On Tue, Sep 17, 2013 at 11:34:21AM -0400, Peter Hurley wrote: > On 09/12/2013 09:09 PM, Fengguang Wu wrote: > >On Fri, Sep 13, 2013 at 08:51:33AM +0800, Fengguang Wu wrote: > >>Hi Peter, > >> > >>FYI, we noticed much increased vmap_area_lock contentions since this > >>commit: > >> > >>commit 20bafb3d23d108bc0a896eb8b7c1501f4f649b77 > >>Author: Peter Hurley > >>Date: Sat Jun 15 10:21:19 2013 -0400 > >> > >> n_tty: Move buffers into n_tty_data > >> > >> Reduce pointer reloading and improve locality-of-reference; > >> allocate read_buf and echo_buf within struct n_tty_data. > > > >Here are some comparison between this commit [o] with its parent commit [*]. > > Hi Fenguang, > > Can you give the particulars of the aim7 test runs below? > I ask because I get _no_ added contention on the vmap_area_lock when I run > these tests on a dual-socket xeon. > > What is the machine configuration(s)? > Are you using the aim7 'multitask' test driver or your own custom driver? > What is the load configuration (ie., constant, linearly increasing, convergence)? > How many loads are you simulating? The aim7 tests are basically ( echo $HOSTNAME echo $workfile echo 1 echo 2000 echo 2 echo 2000 echo 1 ) | ./multitask -t > lock_stat.vmap_area_lock.holdtime-total > [...] > > 489739.50 +978.5% 5281916.05 lkp-ne04/micro/aim7/shell_rtns_1 > > 1601675.63 +906.7% 16123642.52 lkp-snb01/micro/aim7/exec_test > [...] > > 822461.02 +1585.0% 13858430.62 nhm-white/micro/aim7/exec_test > > 9858.11 +2715.9% 277595.41 nhm-white/micro/aim7/fork_test > [...] > > 300.14 +2621.5% 8168.53 nhm-white/micro/aim7/misc_rtns_1 > > 345479.21 +1624.5% 5957828.25 nhm-white/micro/aim7/shell_rtns_1 > > > None of the tests below execute a code path that leads to get_vmalloc_info(). > The only in-kernel user of get_vmalloc_info() is a sysfs read of /proc/meminfo, > which none of the tests below perform. > > What is reading /proc/meminfo? Good point! That may explain it: I'm running a loop: cat /proc/meminfo sleep 1 in all the tests. Thanks, Fengguang > > lock_stat.vmap_area_lock.contentions.get_vmalloc_info > > > > 8cb06c983822103da1cf 20bafb3d23d108bc0a89 > >------------------------ ------------------------ > > 4952.40 +447.0% 27090.40 lkp-ne04/micro/aim7/shell_rtns_1 > > 28410.80 +556.2% 186423.00 lkp-snb01/micro/aim7/exec_test > > 8142.00 +615.4% 58247.33 nhm-white/micro/aim7/exec_test > > 1386.00 +762.6% 11955.20 nhm-white/micro/aim7/shell_rtns_1 > > 42891.20 +561.5% 283715.93 TOTAL lock_stat.vmap_area_lock.contentions.get_vmalloc_info -- 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/