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=-7.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 4CEFBC433DF for ; Wed, 10 Jun 2020 12:59:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D12A20734 for ; Wed, 10 Jun 2020 12:59:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729093AbgFJM7Y (ORCPT ); Wed, 10 Jun 2020 08:59:24 -0400 Received: from outbound-smtp39.blacknight.com ([46.22.139.222]:34965 "EHLO outbound-smtp39.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728965AbgFJM7X (ORCPT ); Wed, 10 Jun 2020 08:59:23 -0400 Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp39.blacknight.com (Postfix) with ESMTPS id 557231945 for ; Wed, 10 Jun 2020 13:59:22 +0100 (IST) Received: (qmail 31682 invoked from network); 10 Jun 2020 12:59:22 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.18.57]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 10 Jun 2020 12:59:22 -0000 Date: Wed, 10 Jun 2020 13:59:20 +0100 From: Mel Gorman To: Amir Goldstein Cc: Jan Kara , linux-fsdevel , linux-kernel Subject: Re: [PATCH] fsnotify: Rearrange fast path to minimise overhead when there is no watcher Message-ID: <20200610125920.GM3127@techsingularity.net> References: <20200608140557.GG3127@techsingularity.net> <20200608160614.GH3127@techsingularity.net> <20200608180130.GJ3127@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Jun 08, 2020 at 11:39:26PM +0300, Amir Goldstein wrote: > > Let me add your optimizations on top of my branch with the needed > > adaptations and send you a branch for testing. > > https://github.com/amir73il/linux/commits/fsnotify_name-for-mel > Sorry for the delay getting back. The machine was busy with other tests and it took a while to reach this on the queue. Fairly good news hackbench-process-pipes 5.7.0 5.7.0 5.7.0 5.7.0 vanilla fastfsnotify-v1r1 amir-20200608 amir-for-mel Amean 1 0.4837 ( 0.00%) 0.4630 * 4.27%* 0.4967 * -2.69%* 0.4680 ( 3.24%) Amean 3 1.5447 ( 0.00%) 1.4557 ( 5.76%) 1.6587 * -7.38%* 1.4807 ( 4.14%) Amean 5 2.6037 ( 0.00%) 2.4363 ( 6.43%) 2.6400 ( -1.40%) 2.4900 ( 4.37%) Amean 7 3.5987 ( 0.00%) 3.4757 ( 3.42%) 3.9040 * -8.48%* 3.5130 ( 2.38%) Amean 12 5.8267 ( 0.00%) 5.6983 ( 2.20%) 6.2593 ( -7.43%) 5.6967 ( 2.23%) Amean 18 8.4400 ( 0.00%) 8.1327 ( 3.64%) 8.9940 ( -6.56%) 7.7240 * 8.48%* Amean 24 11.0187 ( 0.00%) 10.0290 * 8.98%* 11.7247 * -6.41%* 9.5793 * 13.06%* Amean 30 13.1013 ( 0.00%) 12.8510 ( 1.91%) 14.0290 * -7.08%* 12.1630 ( 7.16%) Amean 32 13.9190 ( 0.00%) 13.2410 ( 4.87%) 14.7140 * -5.71%* 13.2457 * 4.84%* First two sets of results are vanilla kernel and just my patch respectively to have two baselines. amir-20200608 is the first git branch you pointed me to and amir-for-mel is this latest branch. Comparing the optimisation and your series, we get hackbench-process-pipes 5.7.0 5.7.0 fastfsnotify-v1r1 amir-for-mel Amean 1 0.4630 ( 0.00%) 0.4680 ( -1.08%) Amean 3 1.4557 ( 0.00%) 1.4807 ( -1.72%) Amean 5 2.4363 ( 0.00%) 2.4900 ( -2.20%) Amean 7 3.4757 ( 0.00%) 3.5130 ( -1.07%) Amean 12 5.6983 ( 0.00%) 5.6967 ( 0.03%) Amean 18 8.1327 ( 0.00%) 7.7240 ( 5.03%) Amean 24 10.0290 ( 0.00%) 9.5793 ( 4.48%) Amean 30 12.8510 ( 0.00%) 12.1630 ( 5.35%) Amean 32 13.2410 ( 0.00%) 13.2457 ( -0.04%) As you can see, your patches with the optimisation layered on top is comparable to just the optimisation on its own. It's not universally better but it would not look like a regression when comparing releases. The differences are mostly within the noise as there is some variability involved for this workload so I would not worry too much about it (caveats are other machines may be different as well as other workloads). A minor issue is that this is probably a bisection hazard. If a series is merged and LKP points the finger somewhere in the middle of your series then I suggest you ask them to test the optimisation commit ID to see if the regression goes away. Thanks Amir. -- Mel Gorman SUSE Labs