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=-8.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS 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 46F8BC83026 for ; Thu, 2 Sep 2021 17:18:08 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0006460FE6 for ; Thu, 2 Sep 2021 17:18:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0006460FE6 Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=xenproject.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.177599.323135 (Exim 4.92) (envelope-from ) id 1mLqLb-0000fi-6b; Thu, 02 Sep 2021 17:17:55 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 177599.323135; Thu, 02 Sep 2021 17:17:55 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mLqLb-0000fb-3Q; Thu, 02 Sep 2021 17:17:55 +0000 Received: by outflank-mailman (input) for mailman id 177599; Thu, 02 Sep 2021 17:17:54 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mLqLa-0000fV-8G for xen-devel@lists.xenproject.org; Thu, 02 Sep 2021 17:17:54 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mLqLa-0001T6-6O for xen-devel@lists.xenproject.org; Thu, 02 Sep 2021 17:17:54 +0000 Received: from iwj (helo=mariner.uk.xensource.com) by xenbits.xenproject.org with local-bsmtp (Exim 4.92) (envelope-from ) id 1mLqLa-0000rf-5N for xen-devel@lists.xenproject.org; Thu, 02 Sep 2021 17:17:54 +0000 Received: from iwj by mariner.uk.xensource.com with local (Exim 4.89) (envelope-from ) id 1mLqLP-0003au-9j; Thu, 02 Sep 2021 18:17:43 +0100 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xenproject.org; s=20200302mail; h=References:In-Reply-To:Subject:Cc:To:Date :Message-ID:Content-Transfer-Encoding:Content-Type:MIME-Version:From; bh=umiEI7GI1ws1A9D4DUyhTQcphKTnzeVma7/jDhfL17Y=; b=u62kLIS/FgD59gVZ9daqK4fLPc XSgGpBGAF3SlzgA8WBEwl9yndpiFnBtpfw4nwNDnq8uPvlFWppzPYSeKoMqRHGUj7D8yRcn+j4oO2 3aHlx4hFMP0TigC2PKqcQSb5JcQ1HdooYxMUpEocyn/+yZTDsdDzHPMwUvPnyACrFcYo=; From: Ian Jackson MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <24881.1846.830472.226170@mariner.uk.xensource.com> Date: Thu, 2 Sep 2021 18:17:42 +0100 To: Jan Beulich Cc: Andrew Cooper , Wei Liu , Roger Pau =?iso-8859-1?Q?Monn=E9?= , Juergen Gross , George Dunlap , "xen-devel\@lists.xenproject.org" Subject: Re: [PATCH 04/12] libxenguest: avoid allocating unused deferred-pages bitmap In-Reply-To: <3aea7472-6c1d-f786-db5f-ead60eb03240@suse.com> References: <912fa390-f9e9-198a-9aee-39fdb9a28fcc@suse.com> <61ff4f26-a9cc-d123-98a0-be6c23f21e9b@suse.com> <44825600-c27b-34ac-01b2-1ffb5e0bf0be@citrix.com> <3aea7472-6c1d-f786-db5f-ead60eb03240@suse.com> X-Mailer: VM 8.2.0b under 24.5.1 (i686-pc-linux-gnu) Jan Beulich writes ("Re: [PATCH 04/12] libxenguest: avoid allocating unused deferred-pages bitmap"): > [stuff] I have read this conversation several times and it is not clear to me whether Andrew was saying Jan's patch is bad, or the existing code is bad. I'm hesitant to give an ack for an optimisation without understanding what the implications might be. Andrew, can you explain what will go wrong if we take Jan's patch ? (I amk not really familiar with this area of the code. If necessary I could go and read it to form my own opinion.) Thanks, Ian.