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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, 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 EC901C64E7A for ; Thu, 3 Dec 2020 13:06:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5285322259 for ; Thu, 3 Dec 2020 13:06:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5285322259 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6919F6B0068; Thu, 3 Dec 2020 08:06:13 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 61B576B006C; Thu, 3 Dec 2020 08:06:13 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 50B556B0070; Thu, 3 Dec 2020 08:06:13 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0121.hostedemail.com [216.40.44.121]) by kanga.kvack.org (Postfix) with ESMTP id 35FBB6B0068 for ; Thu, 3 Dec 2020 08:06:13 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id E3979181AEF39 for ; Thu, 3 Dec 2020 13:06:12 +0000 (UTC) X-FDA: 77551994184.30.hour84_1501efc273bc Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id C57AD180B3C8B for ; Thu, 3 Dec 2020 13:06:12 +0000 (UTC) X-HE-Tag: hour84_1501efc273bc X-Filterd-Recvd-Size: 3952 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Thu, 3 Dec 2020 13:06:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607000771; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pAWiuiXNZmCD4NI8FWNbkeQz1WGY5hi4CeQAq6JE2+8=; b=h20reDg7phJgSuAHXq7wMxGcZwxFS+w5QuDDgvJfZMnlnyXiyxloaPK9sH+AWTQalKMbBc 0nX9Ave5DWY5QG4gor1BCeXqfNNsOAe9KPy4t3qP2qCWO72+B2+08EWcT+U02YnNZfC9/g heSznKmiDrz5a6AfabyTqqDwpr0z1GQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-302-7BB6WgnJNn6xDJtzLueQRA-1; Thu, 03 Dec 2020 08:06:09 -0500 X-MC-Unique: 7BB6WgnJNn6xDJtzLueQRA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 77395612A0; Thu, 3 Dec 2020 13:06:07 +0000 (UTC) Received: from [10.36.113.250] (ovpn-113-250.ams2.redhat.com [10.36.113.250]) by smtp.corp.redhat.com (Postfix) with ESMTP id 889AD18AD6; Thu, 3 Dec 2020 13:06:06 +0000 (UTC) Subject: Re: Deferred Memory Init: How to bring rest of memory online after limiting it with `mem=XG`? To: Paul Menzel Cc: linux-mm@kvack.org, Arjan van de Ven , Feng Tang References: <808e493f-18a2-fe82-46b3-e44fe87e989c@redhat.com> <8a395c1a-764b-9d82-0a12-b1a9254f8d53@molgen.mpg.de> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <7692e410-886e-a1bb-4158-e02305fcd013@redhat.com> Date: Thu, 3 Dec 2020 14:06:05 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <8a395c1a-764b-9d82-0a12-b1a9254f8d53@molgen.mpg.de> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 03.12.20 13:52, Paul Menzel wrote: > Dear David, >=20 >=20 > Thank you for the quick response. >=20 >=20 > Am 03.12.20 um 13:25 schrieb David Hildenbrand: >> On 03.12.20 11:51, Paul Menzel wrote: >=20 >>> I am trying to reduce the startup time of Debian=E2=80=99s Linux 5.9.= 9 on a >>> Intel Kaby Lake system with 32 GB of memory (TUXEDO Book BU1406 (Clev= o >>> N240BU)). >=20 > [=E2=80=A6] >=20 >> We do have deferred meminit in the kernel during boot that can >> initialize memory in parallel. >=20 > Is that used automatically, or do I need to activate it somehow? If your kernel is compiled with CONFIG_DEFERRED_STRUCT_PAGE_INIT it should be enabled automatically. config DEFERRED_STRUCT_PAGE_INIT bool "Defer initialisation of struct pages to kthreads" depends on SPARSEMEM depends on !NEED_PER_CPU_KM depends on 64BIT select PADATA help Ordinarily all struct pages are initialised during early boot in a single thread. On very large machines this can take a considerable amount of time. If this option is set, large machines will bring up a subset of memmap at boot and then initialise the rest in parallel. This has a potential performance impact on tasks running early in the lifetime of the system until these kthreads finish the initialisation. --=20 Thanks, David / dhildenb