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=-0.3 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 0C55CC35646 for ; Fri, 21 Feb 2020 19:33:27 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 BF3F9206E2 for ; Fri, 21 Feb 2020 19:33:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="UQl5s5F5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BF3F9206E2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:35500 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j5E3B-0006wW-RW for qemu-devel@archiver.kernel.org; Fri, 21 Feb 2020 14:33:25 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40266) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j5E2Q-0006QJ-Si for qemu-devel@nongnu.org; Fri, 21 Feb 2020 14:32:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j5E2Q-0000xg-0E for qemu-devel@nongnu.org; Fri, 21 Feb 2020 14:32:38 -0500 Received: from mail-qk1-x744.google.com ([2607:f8b0:4864:20::744]:36692) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1j5E2P-0000wx-Sr; Fri, 21 Feb 2020 14:32:37 -0500 Received: by mail-qk1-x744.google.com with SMTP id t83so2920963qke.3; Fri, 21 Feb 2020 11:32:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=69qEiYN9UARFutxF8nAG/RaQ2+JSdxzdVa6xcpbOCik=; b=UQl5s5F5zgQdVzue+znascwMTF8Dz9oEnL5ZHKG4PNF9ZxvPuK/e8++aLTXKVVP4Fr D5gpGJPEew0pbOJyqjuG1qnwvzBmiwiezWvGspx8USI9BpqzueoyKqraMcv+vQswM+xu tp94kB+zY94mhtMY2gzrU5LXwmqeqe1xnK7yLFsX1DYImjGSeIDvmnMe3esidu9VoEyb 62Bc5eHIJpUO2wjsdz8ilm8VzKgH2QnB+s3RlQ8z6VOB8JLExW1MFtuev9nOXYrVCkpZ 8jBfLosGtCWE3DwmYoIQ8G5FUsuxW2+j5X5OjRYugLtfqw5RoA5z7OwbdRU/oaQkBWe7 0jyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=69qEiYN9UARFutxF8nAG/RaQ2+JSdxzdVa6xcpbOCik=; b=qNx385B65l47aV2fXmxh1MUS5QgrWfSySEBSdzNwRLv9kCTKBQNmupZhnOAn4JSJBQ oiKXC7RGJqHv9z+iDZhgAcCpMDqj5H8Z42AlZZkSSYAZn6TWWlrQ4MZ0Gl1Hy/1cJewh B7ld7gLbUH0UFSubJnRcX2iisytEGZezWF15tNgptusfut25GvfNA8DLPsrOElLqoECF AwR82s5nzwIva3g0KQ/JNy4qG8miTVxOymXwLZf12lWTRnNLhPm/h4PsjlQcoiG6Pi4q vdGAdRTJKBEU1ofjhaXp4hbhkzUOV4qVPR4On8lJy4vFZKW09wzyfJjUAjjbVzb4Id1e I7UQ== X-Gm-Message-State: APjAAAX6CXW1+5C0lOmrLLct+ZLEXWKSvay7AdU/ug6VzqFufS2inm/R eahzAE5EK3FRXXaxLAzYGQZ2nfxKxt3i/oGS8Rs= X-Google-Smtp-Source: APXvYqwfMPcl+AeQRpG8qmwU0vuQf3xaQUfAE6BF/oF/323tH6AXTw4P0zzOs1aUjHazssMOXh05RZl0Dshke2AJ+Xc= X-Received: by 2002:a37:e55:: with SMTP id 82mr36008071qko.370.1582313557161; Fri, 21 Feb 2020 11:32:37 -0800 (PST) MIME-Version: 1.0 References: <20200218224811.30050-1-andrzej.jakowski@linux.intel.com> <20200221134555.GK1484511@stefanha-x1.localdomain> In-Reply-To: From: Stefan Hajnoczi Date: Fri, 21 Feb 2020 19:32:26 +0000 Message-ID: Subject: Re: [PATCH v1] block/nvme: introduce PMR support from NVMe 1.4 spec To: Andrzej Jakowski Content-Type: text/plain; charset="UTF-8" X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::744 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Haozhong Zhang , qemu block , qemu-devel , Max Reitz , Keith Busch , Zhang Yi , Junyan He , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Andrzej, After having looked at the PMRWBM part of the spec, I think that the Bit 1 mode should be implemented for slightly better performance. Bit 0 mode is not well-suited to virtualization for the reasons I mentioned in the previous email. The spec describes Bit 1 mode as "The completion of a read to the PMRSTS register shall ensure that all prior writes to the Persistent Memory Region have completed and are persistent". Stefan