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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6FBA1C433F5 for ; Sun, 17 Oct 2021 18:42:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C17F61050 for ; Sun, 17 Oct 2021 18:42:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344453AbhJQSon (ORCPT ); Sun, 17 Oct 2021 14:44:43 -0400 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:16483 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231517AbhJQSom (ORCPT ); Sun, 17 Oct 2021 14:44:42 -0400 IronPort-HdrOrdr: =?us-ascii?q?A9a23=3Alu3RXasYaaCFfrr/5E0jv4Rd7skDXdV00zEX?= =?us-ascii?q?/kB9WHVpm5Sj5qWTdYcgpHvJYVEqKQodcLG7SdG9qBznlKKdjbN6AV7mZniFhI?= =?us-ascii?q?LKFvAZ0WKB+V3d8kTFn4Y36U4jSdkcNDSaNzRHZLPBjjVQZOxO/DDoys2VbKzl?= =?us-ascii?q?vhBQpElRGsddBilCe3+mLnE=3D?= X-IronPort-AV: E=Sophos;i="5.84,326,1620684000"; d="scan'208";a="534379835" Received: from 173.121.68.85.rev.sfr.net (HELO hadrien) ([85.68.121.173]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Oct 2021 20:42:31 +0200 Date: Sun, 17 Oct 2021 20:42:31 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@hadrien To: Randy Dunlap cc: linux-kernel@vger.kernel.org, Masahiro Yamada , Michal Marek , linux-kbuild@vger.kernel.org Subject: Re: build reproducibility In-Reply-To: <7e5485df-a17b-304b-627d-9a85d2464df3@infradead.org> Message-ID: References: <7e5485df-a17b-304b-627d-9a85d2464df3@infradead.org> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org On Sun, 17 Oct 2021, Randy Dunlap wrote: > On 10/17/21 11:12 AM, Julia Lawall wrote: > > Hello, > > > > If I do the following: > > > > git clean -dfx > > cp saved_config .config > > make olddefconfig && make && make modules_install && make install > > > > Should I always end up with the same kernel, regardless of the kernel that > > is currently running on the machine? > > > > I see a large performance difference between Linux 5.10 and all versions > > afterwards for a particular benchmark. I am unable to bisect the problem > > eg between 5.10 and 5.11, because as soon as I come to a kernel that gives > > the bad performance, all of the kernels that I generate subsequently in > > the bisecting process (using the above commands) also have the bad > > performance. > > > > It could of course be that I have completely misinterpreted the problem, > > and it has nothing to do with the kernel. But I have tested the program a > > lot when only working on variants of Linux 5.9. I only start to have > > problems when I use versions >= 5.11. > > Hi, > > My "guess" is that this has something to do with the build > reusing some current file(s) that need to be rebuilt. > I.e., adding a "make clean" or "make proper" might be needed. This was my guess too. But I have the git clean -dfx. I did a comparison with make distclean and this does a little more (mostly some files in tools). thanks, julia > > I say this only because sometimes I cannot even reproduce > a build that has errors or warnings unless I prefix it with > make clean or mrproper. (i.e., nothing to do with booting > and running the new kernel) > Even though the .config file has changed and I do > "make olddefconfig", the same build errors do not show up > unless I do the clean or mrproper step also. > > > -- > ~Randy >