Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932279Ab1C1TtB (ORCPT ); Mon, 28 Mar 2011 15:49:01 -0400 Received: from cantor.suse.de ([195.135.220.2]:47540 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932140Ab1C1TtA (ORCPT ); Mon, 28 Mar 2011 15:49:00 -0400 Date: Mon, 28 Mar 2011 21:48:57 +0200 From: Jan Kara To: Jeff Moyer Cc: Jan Kara , "Alex,Shi" , Corrado Zoccolo , "Li, Shaohua" , Vivek Goyal , "tytso@mit.edu" , "jaxboe@fusionio.com" , "linux-kernel@vger.kernel.org" , "Chen, Tim C" Subject: Re: [performance bug] kernel building regression on 64 LCPUs machine Message-ID: <20110328194857.GB7184@quack.suse.cz> References: <20110302094246.GA7496@quack.suse.cz> <20110302211748.GF7496@quack.suse.cz> <20110304153248.GC2649@quack.suse.cz> <1300779499.30136.353.camel@debian> <20110322161405.GB19716@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2101 Lines: 55 On Tue 22-03-11 13:46:06, Jeff Moyer wrote: > Jan Kara writes: > > > Jeff, I suppose the log files of fs_mark processes are on the same > > device as the test directory, aren't they - that might explain the > > flusher thread doing IO? The patch below > > No. My test environments are sane. The file system is on a completely > separate disk and it is unmounted and remounted in between each run. > That should take care of any lost flushes. OK, I understand but let me clear out one thing. What fs_mark seems to be doing is: for given number of iterations { (-L option, default 1) fork each thread { start timer for i = 1 .. 10000 { (could be changed by option -n) write file i } stop timer for i = 1 .. 10000 { unlink file i } write statistics to log file exit } read all log files, write combined results to another log file } I see from blktrace data that indeed you are running more than one iteration of the fs_mark process so the problem I was wondering about is whether unlinking or writing of log files cannot interefere with the IO happening while the timer is running. Now log files are rather small so I don't really think they cause any problem but they could be the data flusher thread writes - they are stored in the current directory (unless you use -l option). So I my question was aiming at where these files are stored - do you specify -l option and if not, what is the current directory of fs_mark process in your setup? I think unlinks could possibly cause problems and that's why I suggested we add sync() to the parent process before it runs the next iteration... > Did you receive my last couple of private emails commenting on the trace > data? Yes, I did get them. I'll reply to them in a while. Honza -- Jan Kara SUSE Labs, CR -- 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/