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 250F6C4338F for ; Tue, 10 Aug 2021 18:31:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0978C60E76 for ; Tue, 10 Aug 2021 18:31:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233919AbhHJSbr (ORCPT ); Tue, 10 Aug 2021 14:31:47 -0400 Received: from mga09.intel.com ([134.134.136.24]:43767 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233165AbhHJSbg (ORCPT ); Tue, 10 Aug 2021 14:31:36 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10072"; a="214951145" X-IronPort-AV: E=Sophos;i="5.84,310,1620716400"; d="scan'208";a="214951145" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Aug 2021 11:30:57 -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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > 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