From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <victork@redhat.com>
Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28])
 by dpdk.org (Postfix) with ESMTP id 1D0C15683
 for <dev@dpdk.org>; Wed,  2 Dec 2015 16:58:28 +0100 (CET)
Received: from int-mx13.intmail.prod.int.phx2.redhat.com
 (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26])
 by mx1.redhat.com (Postfix) with ESMTPS id 54EEC8E362;
 Wed,  2 Dec 2015 15:58:27 +0000 (UTC)
Received: from redhat.com (vpn-201-9.tlv.redhat.com [10.35.201.9])
 by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id
 tB2FwPQW030060; Wed, 2 Dec 2015 10:58:26 -0500
Date: Wed, 2 Dec 2015 17:58:24 +0200
From: Victor Kaplansky <victork@redhat.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Message-ID: <20151202170233-mutt-send-email-victork@redhat.com>
References: <1449027793-30975-1-git-send-email-yuanhan.liu@linux.intel.com>
 <1449027793-30975-4-git-send-email-yuanhan.liu@linux.intel.com>
 <20151202155405-mutt-send-email-victork@redhat.com>
 <20151202143802.GT2325@yliu-dev.sh.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20151202143802.GT2325@yliu-dev.sh.intel.com>
X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26
Cc: dev@dpdk.org, "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 3/4] vhost: log vring changes
X-BeenThere: dev@dpdk.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
X-List-Received-Date: Wed, 02 Dec 2015 15:58:28 -0000

On Wed, Dec 02, 2015 at 10:38:02PM +0800, Yuanhan Liu wrote:
> On Wed, Dec 02, 2015 at 04:07:02PM +0200, Victor Kaplansky wrote:
> > On Wed, Dec 02, 2015 at 11:43:12AM +0800, Yuanhan Liu wrote:
> > > Invoking vhost_log_write() to mark corresponding page as dirty while
> > > updating used vring.
> > 
> > Looks good, thanks!
> > 
> > I didn't find where you log the dirty pages in result of data
> > written to the buffers pointed by the descriptors in RX vring.
> > AFAIU, the buffers of RX queue reside in guest's memory and have
> > to be marked as dirty if they are written. What do you say?
> 
> Yeah, we should. I got a question then: why log_guest_addr is set
> to the physical address of used vring in guest? I mean, apparently,
> we need log more changes other than used vring only.

The physical address of used vring sent to the back-end, since
otherwise back-end has to perform virtual to physical
translation, and we want to avoid this. The dirty buffers has to
be marked as well, but their guest's physical address is known
directly from the descriptors.

> 
> 	--yliu