From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27000C00307 for ; Mon, 9 Sep 2019 06:21:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0AE3B20828 for ; Mon, 9 Sep 2019 06:21:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727987AbfIIGVA (ORCPT ); Mon, 9 Sep 2019 02:21:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48624 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727898AbfIIGVA (ORCPT ); Mon, 9 Sep 2019 02:21:00 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C3B4A30A00CF; Mon, 9 Sep 2019 06:20:59 +0000 (UTC) Received: from rh (ovpn-116-55.phx2.redhat.com [10.3.116.55]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7E92110016EB; Mon, 9 Sep 2019 06:20:59 +0000 (UTC) Received: from [::1] (helo=rh) by rh with esmtps (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1i7D2i-0001wB-HC; Mon, 09 Sep 2019 16:20:52 +1000 Date: Mon, 9 Sep 2019 16:20:49 +1000 From: Dave Chinner To: Rong Chen Cc: "Darrick J. Wong" , Christoph Hellwig , LKML , linux-xfs@vger.kernel.org, lkp@01.org Subject: Re: [xfs] 610125ab1e: fsmark.app_overhead -71.2% improvement Message-ID: <20190909062049.GQ2254@rh> References: <20190909015849.GN15734@shao2-debian> <20190909053236.GP2254@rh> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Mon, 09 Sep 2019 06:20:59 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 09, 2019 at 02:06:54PM +0800, Rong Chen wrote: > Hi Dave, > > On 9/9/19 1:32 PM, Dave Chinner wrote: > > On Mon, Sep 09, 2019 at 09:58:49AM +0800, kernel test robot wrote: > > > Greeting, > > > > > > FYI, we noticed a -71.2% improvement of fsmark.app_overhead due to commit: > > A negative improvement? That's somewhat ambiguous... > > Sorry for causing the misunderstanding, it's a improvement not a regression. > > > > > > > 0e822255f95db400 610125ab1e4b1b48dcffe74d9d8 > > > ---------------- --------------------------- > > > %stddev %change %stddev > > > \ | \ > > > 1.095e+08 -71.2% 31557568 fsmark.app_overhead > > > 6157 +95.5% 12034 fsmark.files_per_sec > > So, the files/s rate doubled, and the amount of time spent in > > userspace by the fsmark app dropped by 70%. > > > > > 167.31 -47.3% 88.25 fsmark.time.elapsed_time > > > 167.31 -47.3% 88.25 fsmark.time.elapsed_time.max > > Wall time went down by 50%. > > > > > 91.00 -8.8% 83.00 fsmark.time.percent_of_cpu_this_job_got > > > 148.15 -53.2% 69.38 fsmark.time.system_time > > As did system CPU. > > > > IOWs, this change has changed create performance by a factor of 4 - > > the file create is 2x faster for half the CPU spent. > > > > I don't think this is a negative improvement - it's a large positive > > improvement. I suspect that you need to change the metric > > classifications for this workload... > To avoid misunderstanding, we'll use fsmark.files_per_sec instead of > fsmark.app_overhead in the subject. Well, the two are separate ways of measuring improvement. A change in one without a change in the other is just as significant as a change in both... Cheers, Dave. -- Dave Chinner dchinner@redhat.com