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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 46E14C43331 for ; Fri, 3 Apr 2020 01:33:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 11559206A3 for ; Fri, 3 Apr 2020 01:33:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="bXEmj37N" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390174AbgDCBd2 (ORCPT ); Thu, 2 Apr 2020 21:33:28 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46752 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389108AbgDCBd2 (ORCPT ); Thu, 2 Apr 2020 21:33:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:To: Subject:Sender:Reply-To:Cc:Content-ID:Content-Description; bh=SCRT2UG5Qsu+Cz6vuDN/Aw7Mnmw2doVb42M3j+OCBgI=; b=bXEmj37NUbVC9gRqY/YRlj7WOt x+g7JTU2gOH3VMLC/iY4BVvBHpErcd9UBzESM6YdPt/2McfvSll74J+z5Pd4cW183QdiZKmwY+R95 o10eU+s/ztBp0LhDN5eq9lZyO/wehBGn3gRqjq9ZYj4AeiXxQEoyDU1vo8hYJTVdrwPHJUA4bQnq4 +D/MBAFbEDmVqpveVjQhtDWaS5bZPCfE23YEbb6UKv+Him45s1gX9rik1OOMKs1ZyE0LcKWME/V1l peuSK/0kbu/BpNwI3IfLzcNUSIXQaFG8kbbUdFnul44KHYwtY+6Hz0TIcVN4WPCNJ5xryZQP51pLx oclesC/w==; Received: from [2601:1c0:6280:3f0:897c:6038:c71d:ecac] by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jKBD5-0005KG-Vl; Fri, 03 Apr 2020 01:33:28 +0000 Subject: Re: why does "mem auto-init: clearing system memory may take some time..." takes about 14 sec under 5.4.17 but only few msec under 5.5.1? To: =?UTF-8?Q?Toralf_F=c3=b6rster?= , Linux Kernel References: <5f7c4aac-2b6c-3dc3-cf4d-ee6c19d0d959@gmx.de> From: Randy Dunlap Message-ID: <011e98b7-e73d-99e3-d0e7-5b68f89636bf@infradead.org> Date: Thu, 2 Apr 2020 18:33:24 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <5f7c4aac-2b6c-3dc3-cf4d-ee6c19d0d959@gmx.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/30/20 2:12 AM, Toralf Förster wrote: > On 3/30/20 4:55 AM, Randy Dunlap wrote: >> Hi > Toralf, >> >> Curious/odd. >> >> Do you have the kernel .config files for 5.4.17 and 5.5.1? >> Looks like it would have to be a config difference AFAICT. > > Sry, > > attached the wrong configs at my previous mail. Here are 2 configs from the affected server attached. Hi Toralf, There's not much difference in the kernel config files, although the one for 5.5.8 does have CONFIG_DEBUG_KERNEL=y while it's not set in 5.4.17. I built both kernels and booted them. I don't see a big time difference like you reported. Here's what I get: 5.4.17: [ 0.112274] mem auto-init: stack:off, heap alloc:on, heap free:on [ 0.112275] mem auto-init: clearing system memory may take some time... [ 0.621019] Memory: 3935312K/4095412K available (10243K kernel code, 1427K rwdata, 1924K rodata, 968K init, 768K bss, 160100K reserved, 0K cma-reserved) and 5.5.8: [ 0.114455] mem auto-init: stack:off, heap alloc:on, heap free:on [ 0.114456] mem auto-init: clearing system memory may take some time... [ 0.622989] Memory: 3933200K/4095412K available (12291K kernel code, 1438K rwdata, 1952K rodata, 964K init, 708K bss, 162212K reserved, 0K cma-reserved) but then a lot of the timestamps in your 5.5.8 log are 0. -- ~Randy