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 915D2C433EF for ; Sun, 17 Oct 2021 18:19:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CC1D60F22 for ; Sun, 17 Oct 2021 18:19:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230463AbhJQSVY (ORCPT ); Sun, 17 Oct 2021 14:21:24 -0400 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:61550 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232672AbhJQSVW (ORCPT ); Sun, 17 Oct 2021 14:21:22 -0400 X-Greylist: delayed 428 seconds by postgrey-1.27 at vger.kernel.org; Sun, 17 Oct 2021 14:21:22 EDT IronPort-HdrOrdr: =?us-ascii?q?A9a23=3AqPt+Z6A9PwlBdFrlHemf55DYdb4zR+YMi2TD?= =?us-ascii?q?gXoQdfU1SK2lfq+V7YUmPHXP4gr5NEtNpTn/Atj/fZqGz+8X3WB5B97LN2TbUQ?= =?us-ascii?q?CTQr2Kg7GM/xTQXwfk8OkY+aB+GpIOaqyUfDwK6redkXDIa6dasaP3jdHV9Jjj?= =?us-ascii?q?80s=3D?= X-IronPort-AV: E=Sophos;i="5.84,326,1620684000"; d="scan'208";a="534378688" 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 20:12:00 +0200 Date: Sun, 17 Oct 2021 20:12:00 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@hadrien To: linux-kernel@vger.kernel.org, Masahiro Yamada , Michal Marek , linux-kbuild@vger.kernel.org Subject: build reproducibility Message-ID: 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 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. thanks, julia