Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932703AbXAJDUx (ORCPT ); Tue, 9 Jan 2007 22:20:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932702AbXAJDUx (ORCPT ); Tue, 9 Jan 2007 22:20:53 -0500 Received: from nigel.suspend2.net ([203.171.70.205]:44177 "EHLO nigel.suspend2.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932696AbXAJDUw (ORCPT ); Tue, 9 Jan 2007 22:20:52 -0500 Subject: Re: How git affects kernel.org performance From: Nigel Cunningham Reply-To: nigel@nigel.suspend2.net To: Fengguang Wu Cc: Linus Torvalds , Theodore Tso , Suparna Bhattacharya , Andrew Morton , Willy Tarreau , "H. Peter Anvin" , git@vger.kernel.org, "J.H." , Randy Dunlap , Pavel Machek , kernel list , webmaster@kernel.org, "linux-ext4@vger.kernel.org" In-Reply-To: <20070110015739.GA26978@mail.ustc.edu.cn> References: <1168140954.2153.1.camel@nigel.suspend2.net> <45A08269.4050504@zytor.com> <45A083F2.5000000@zytor.com> <20070107085526.GR24090@1wt.eu> <20070107011542.3496bc76.akpm@osdl.org> <20070108030555.GA7289@in.ibm.com> <20070108125819.GA32756@thunk.org> <368329554.17014@ustc.edu.cn> <20070110015739.GA26978@mail.ustc.edu.cn> Content-Type: text/plain Date: Wed, 10 Jan 2007 14:20:49 +1100 Message-Id: <1168399249.2585.6.camel@nigel.suspend2.net> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1942 Lines: 75 Hi. On Wed, 2007-01-10 at 09:57 +0800, Fengguang Wu wrote: > On Tue, Jan 09, 2007 at 08:23:32AM -0800, Linus Torvalds wrote: > > > > > > On Tue, 9 Jan 2007, Fengguang Wu wrote: > > > > > > > > The fastest and probably most important thing to add is some readahead > > > > smarts to directories --- both to the htree and non-htree cases. If > > > > > > Here's is a quick hack to practice the directory readahead idea. > > > Comments are welcome, it's a freshman's work :) > > > > Well, I'd probably have done it differently, but more important is whether > > this actually makes a difference performance-wise. Have you benchmarked it > > at all? > > Yes, a trivial test shows a marginal improvement, on a minimal debian system: > > # find / | wc -l > 13641 > > # time find / > /dev/null > > real 0m10.000s > user 0m0.210s > sys 0m4.370s > > # time find / > /dev/null > > real 0m9.890s > user 0m0.160s > sys 0m3.270s > > > Doing an > > > > echo 3 > /proc/sys/vm/drop_caches > > > > is your friend for testing things like this, to force cold-cache > > behaviour.. > > Thanks, I'll work out numbers on large/concurrent dir accesses soon. I gave it a try, and I'm afraid the results weren't pretty. I did: time find /usr/src | wc -l on current git with (3 times) and without (5 times) the patch, and got with: real 54.306, 54.327, 53.742s usr 0.324, 0.284, 0.234s sys 2.432, 2.484, 2.592s without: real 24.413, 24.616, 24.080s usr 0.208, 0.316, 0.312s sys: 2.496, 2.440, 2.540s Subsequent runs without dropping caches did give a significant improvement in both cases (1.821/.188/1.632 is one result I wrote with the patch applied). Regards, Nigel - 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/