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=-5.3 required=3.0 tests=BAYES_00, 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 B6E49C433DB for ; Mon, 8 Mar 2021 18:48:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3390060233 for ; Mon, 8 Mar 2021 18:48:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3390060233 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9406A8D0061; Mon, 8 Mar 2021 13:48:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 917548D001D; Mon, 8 Mar 2021 13:48:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7DF6E8D0061; Mon, 8 Mar 2021 13:48:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0097.hostedemail.com [216.40.44.97]) by kanga.kvack.org (Postfix) with ESMTP id 613CC8D001D for ; Mon, 8 Mar 2021 13:48:45 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 2BB668249980 for ; Mon, 8 Mar 2021 18:48:45 +0000 (UTC) X-FDA: 77897593410.14.863F5F2 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf02.hostedemail.com (Postfix) with ESMTP id 3EBFE4080F48 for ; Mon, 8 Mar 2021 18:48:38 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 98111AC1F; Mon, 8 Mar 2021 18:48:43 +0000 (UTC) Date: Mon, 8 Mar 2021 19:48:40 +0100 From: Oscar Salvador To: Dave Hansen Cc: Andrew Morton , David Hildenbrand , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 2/3] x86/vmemmap: Drop handling of 1GB vmemmap ranges Message-ID: <20210308184840.GC25767@linux> References: <20210301083230.30924-1-osalvador@suse.de> <20210301083230.30924-3-osalvador@suse.de> <62c5b490-353a-ca3a-d2c8-f02189210c32@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <62c5b490-353a-ca3a-d2c8-f02189210c32@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 3EBFE4080F48 X-Stat-Signature: myot7ryo1318w9x3eh1gpboxgoiuiq7b Received-SPF: none (suse.de>: No applicable sender policy available) receiver=imf02; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: none/none X-HE-Tag: 1615229318-639557 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 Thu, Mar 04, 2021 at 10:42:59AM -0800, Dave Hansen wrote: > On 3/1/21 12:32 AM, Oscar Salvador wrote: > > We never get to allocate 1GB pages when mapping the vmemmap range. > > Drop the dead code both for the aligned and unaligned cases and leave > > only the direct map handling. > > Could you elaborate a bit on why 1GB pages are never used? It is just > unlikely to have a 64GB contiguous area of memory that needs 1GB of > contiguous vmemmap? Or, does the fact that sections are smaller than > 64GB keeps this from happening? AFAIK, the biggest we populate vmemmap pages with is 2MB, plus the fact that as you pointed out, memory sections on x86_64 are 128M, which is way smaller than what would require to allocate a 1GB for vmemmap pages. Am I missing something? -- Oscar Salvador SUSE L3