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=-2.2 required=3.0 tests=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 28622C433DF for ; Thu, 11 Jun 2020 14:18:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E379120801 for ; Thu, 11 Jun 2020 14:18:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E379120801 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 58DD68D009C; Thu, 11 Jun 2020 10:18:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 53DDF8D0084; 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Thu, 11 Jun 2020 14:16:04 +0000 (UTC) IronPort-SDR: P1JLJRrQ8H0Icas6zNgIh6VBPl+fOAgcG4+EWis0rqW/VCHp8E9wRtrluV4UU8stYKfzhUKl+B Qwe/JDoFvX2g== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jun 2020 07:16:03 -0700 IronPort-SDR: VI/8J01y+zCQPmk4C/pMv9+eB4Rb391N/B7Hk52XoTny7wwt3F2ncU5zSli5VmL77HsBZ2DAaS uMODUIhy1CDg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,499,1583222400"; d="scan'208";a="275343592" Received: from hbaravin-mobl.amr.corp.intel.com (HELO [10.255.4.112]) ([10.255.4.112]) by orsmga006.jf.intel.com with ESMTP; 11 Jun 2020 07:16:01 -0700 Subject: Re: [PATCH v2] x86/mm: use max memory block size on bare metal To: Daniel Jordan , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , Andy Lutomirski , Dave Hansen , David Hildenbrand , Michal Hocko , Pavel Tatashin , Peter Zijlstra , Steven Sistare References: <20200609225451.3542648-1-daniel.m.jordan@oracle.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200609225451.3542648-1-daniel.m.jordan@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Rspamd-Queue-Id: 8533E32291 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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 6/9/20 3:54 PM, Daniel Jordan wrote: > + /* > + * Use max block size to minimize overhead on bare metal, where > + * alignment for memory hotplug isn't a concern. > + */ > + if (hypervisor_is_type(X86_HYPER_NATIVE)) { > + bz =3D MAX_BLOCK_SIZE; > + goto done; > + } What ends up being the worst case scenario? Booting a really small bare-metal x86 system, say with 64MB or 128MB of RAM? What's the overhead there?