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,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 CBB52C4338F for ; Tue, 10 Aug 2021 18:31:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5CAB860E09 for ; Tue, 10 Aug 2021 18:31:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5CAB860E09 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 01BE78D0006; Tue, 10 Aug 2021 14:31:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F0E288D0001; Tue, 10 Aug 2021 14:31:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E23F58D0006; Tue, 10 Aug 2021 14:31:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0037.hostedemail.com [216.40.44.37]) by kanga.kvack.org (Postfix) with ESMTP id C88838D0001 for ; Tue, 10 Aug 2021 14:31:02 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 750D7231A4 for ; Tue, 10 Aug 2021 18:31:02 +0000 (UTC) X-FDA: 78460012764.01.3D2D543 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by imf14.hostedemail.com (Postfix) with ESMTP id A6051600AAA6 for ; Tue, 10 Aug 2021 18:31:01 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10072"; a="202147247" X-IronPort-AV: E=Sophos;i="5.84,310,1620716400"; d="scan'208";a="202147247" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Aug 2021 11:30:58 -0700 X-IronPort-AV: E=Sophos;i="5.84,310,1620716400"; d="scan'208";a="515943455" Received: from akleen-mobl1.amr.corp.intel.com (HELO [10.209.69.62]) ([10.209.69.62]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Aug 2021 11:30:56 -0700 Subject: Re: [PATCH 1/5] mm: Add support for unaccepted memory To: Dave Hansen , "Kirill A. Shutemov" , Borislav Petkov , Andy Lutomirski , Sean Christopherson , Andrew Morton , Joerg Roedel Cc: Kuppuswamy Sathyanarayanan , David Rientjes , Vlastimil Babka , Tom Lendacky , Thomas Gleixner , Peter Zijlstra , Paolo Bonzini , Ingo Molnar , Varad Gautam , Dario Faggioli , x86@kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" References: <20210810062626.1012-1-kirill.shutemov@linux.intel.com> <20210810062626.1012-2-kirill.shutemov@linux.intel.com> From: Andi Kleen Message-ID: <9748c07c-4e59-89d0-f425-c57f778d1b42@linux.intel.com> Date: Tue, 10 Aug 2021 11:30:55 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: A6051600AAA6 Authentication-Results: imf14.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none); spf=none (imf14.hostedemail.com: domain of ak@linux.intel.com has no SPF policy when checking 134.134.136.20) smtp.mailfrom=ak@linux.intel.com X-Stat-Signature: jmgq9ut7mbpawsme3g11xfisayrgkces X-HE-Tag: 1628620261-757663 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: > So, this is right in the fast path of the page allocator. It's a > one-time thing per 2M page, so it's not permanent. > > *But* there's both a global spinlock and a firmware call hidden in > clear_page_offline(). That's *GOT* to hurt if you were, for instance, > running a benchmark while this code path is being tickled. Not just to > > That could be just downright catastrophic for scalability, albeit > temporarily This would be only a short blib at initialization until the system reaches steady state. So yes it would be temporary, but very short at that. -Andi