Received: by 2002:a25:4158:0:0:0:0:0 with SMTP id o85csp2208620yba; Mon, 6 May 2019 01:32:51 -0700 (PDT) X-Google-Smtp-Source: APXvYqx6FqPsIAJ6bhEqMXz4/tg6dnsVA7lnzFzh26zf3p8sqxU6fWR8UqsSzauBjzbVchDNesCh X-Received: by 2002:a63:6884:: with SMTP id d126mr8850794pgc.154.1557131571190; Mon, 06 May 2019 01:32:51 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1557131571; cv=none; d=google.com; s=arc-20160816; b=PlZQqdoCC21uMP5yCu9riR/gPumYWufQIDevWHDtSXU3BPDxxXDTahTF8181QXaRK3 oi11ELOT5GalPN1h5I6OxMIjRUkqqg7s/6giiuO2IMpTfjYLgNw0axoXupKPZRlDzQLO b/opEEs7FWnBnhZPR3elgXwxSP9ixg/BOfTJHU4x09qhwmriMGGdk21iGt++1DwnQ8zI mJGhUWenmDvxIzqbe1EMHVrec38HlQ121epvPHvkXF74fGzzfJPHo89O6255sha4uUcK 0GVef1bXLNny36/d0YrbCSaUJlwXqI0WWkgWBQbmzcNQiqPAOb12tEsFzC5d0uAUeY7I 0Z2A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:date:cc:to:from:subject:message-id; bh=O29ybDx0k467aGN79+2o7JP+KZhQ9ed0Hrf4E1vtbrY=; b=wWcpmL7MncZ/Q7iZDfs9Q4G0lZ2hTSFrjO+wM6ILhHjMFljD1JWcPtazwOOmjmS5VU lB+gdOHfv4hgO83y47jNdz0ofaBtSge30B1oZOuUVDU4Qj8vjL+eaMBINO395rCrIrGr yXbMztA65YMwcIp+yICI1RekFFp3YgvEdtvy+kGf92rEz/hWjIbaUkqC6FlFYg4qiMzt NN6O5ny8pNRW1gOG0IGQIgFqmbHmmGUuYhConlM2kUBfQ7Hdptzxn5WswDcvU9VdN5/j +cBK4urU9UsIJDSeFJKiJbt2CVB40levjF2XIHgNYjoyYbOfIIozgJTwP6YAAT+cZyAC aO9Q== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id f34si11488064plf.258.2019.05.06.01.32.35; Mon, 06 May 2019 01:32:51 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726149AbfEFIbf (ORCPT + 99 others); Mon, 6 May 2019 04:31:35 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50530 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725846AbfEFIbe (ORCPT ); Mon, 6 May 2019 04:31:34 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 397CE81DFA; Mon, 6 May 2019 08:31:34 +0000 (UTC) Received: from maximlenovopc.usersys.redhat.com (unknown [10.35.206.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4C8A11001DDE; Mon, 6 May 2019 08:31:25 +0000 (UTC) Message-ID: <1cc7efd1852f298b01f09955f2c4bf3b20cead13.camel@redhat.com> Subject: Re: [PATCH v2 06/10] nvme/core: add mdev interfaces From: Maxim Levitsky To: Christoph Hellwig , Max Gurtovoy Cc: Fam Zheng , kvm@vger.kernel.org, Wolfram Sang , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Keith Busch , Kirti Wankhede , Mauro Carvalho Chehab , "Paul E . McKenney" , Sagi Grimberg , Christoph Hellwig , Liang Cunming , Jens Axboe , Alex Williamson , John Ferlan , Liu Changpeng , Jens Axboe , Greg Kroah-Hartman , Nicolas Ferre , Paolo Bonzini , Amnon Ilan , "David S . Miller" Date: Mon, 06 May 2019 11:31:27 +0300 In-Reply-To: <20190504064938.GA30814@lst.de> References: <20190502114801.23116-1-mlevitsk@redhat.com> <20190502114801.23116-7-mlevitsk@redhat.com> <20190503122902.GA5081@infradead.org> <20190504064938.GA30814@lst.de> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 06 May 2019 08:31:34 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2019-05-04 at 08:49 +0200, Christoph Hellwig wrote: > On Fri, May 03, 2019 at 10:00:54PM +0300, Max Gurtovoy wrote: > > Don't see a big difference of taking NVMe queue and namespace/partition to > > guest OS or to P2P since IO is issued by external entity and pooled outside > > the pci driver. > > We are not going to the queue aside either way.. That is where the > last patch in this series is already working to, and which would be > the sensible vhost model to start with. Why are you saying that? I actualy prefer to use a sepearate queue per software nvme controller, tat because of lower overhead (about half than going through the block layer) and it better at QoS as the separate queue (or even few queues if needed) will give the guest a mostly guaranteed slice of the bandwidth of the device. The only drawback of this is some code duplication but that can be worked on with some changes in the block layer. The last patch in my series was done with 2 purposes in mind which are to measure the overhead, and to maybe utilize that as a failback to non nvme devices. Best regards, Maxim Levitsky