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=-2.3 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 6079AC4360D for ; Sun, 8 Sep 2019 21:46:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 426AC214DB for ; Sun, 8 Sep 2019 21:46:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730918AbfIHVqK (ORCPT ); Sun, 8 Sep 2019 17:46:10 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:45980 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730816AbfIHVqK (ORCPT ); Sun, 8 Sep 2019 17:46:10 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.2 #3 (Red Hat Linux)) id 1i750T-00022V-AW; Sun, 08 Sep 2019 21:46:01 +0000 Date: Sun, 8 Sep 2019 22:46:01 +0100 From: Al Viro To: kernel test robot Cc: David Howells , Hugh Dickins , LKML , linux-fsdevel@vger.kernel.org, lkp@01.org Subject: Re: [vfs] 8bb3c61baf: vm-scalability.median -23.7% regression Message-ID: <20190908214601.GC1131@ZenIV.linux.org.uk> References: <20190903084122.GH15734@shao2-debian> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190903084122.GH15734@shao2-debian> User-Agent: Mutt/1.12.0 (2019-05-25) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 03, 2019 at 04:41:22PM +0800, kernel test robot wrote: > Greeting, > > FYI, we noticed a -23.7% regression of vm-scalability.median due to commit: > > > commit: 8bb3c61bafa8c1cd222ada602bb94ff23119e738 ("vfs: Convert ramfs, shmem, tmpfs, devtmpfs, rootfs to use the new mount API") > https://kernel.googlesource.com/pub/scm/linux/kernel/git/viro/vfs.git work.mount > > in testcase: vm-scalability > on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 128G memory > with following parameters: > > runtime: 300s > size: 16G > test: shm-pread-rand > cpufreq_governor: performance > ucode: 0xb000036 That thing loses size=... option. Both size= and nr_blocks= affect the same thing (->max_blocks), but the parser keeps track of the options it has seen and applying the parsed data to superblock checks only whether nr_blocks= had been there. IOW, size= gets parsed, but the result goes nowhere. I'm not sure whether it's better to fix the patch up or redo it from scratch - it needs to be carved up anyway and it's highly non-transparent, so I'm probably going to replace the damn thing entirely with something that would be easier to follow.