From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 23FAC293C; Fri, 4 Nov 2016 09:10:22 +0100 (CET) Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9AB78C056792; Fri, 4 Nov 2016 08:10:21 +0000 (UTC) Received: from [10.36.4.213] (vpn1-4-213.ams2.redhat.com [10.36.4.213]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uA48AJFl025619 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 4 Nov 2016 04:10:20 -0400 To: Yuanhan Liu , dev@dpdk.org References: <1478189400-14606-1-git-send-email-yuanhan.liu@linux.intel.com> <1478189400-14606-2-git-send-email-yuanhan.liu@linux.intel.com> Cc: stable@dpdk.org, Ilya Maximets From: Maxime Coquelin Message-ID: Date: Fri, 4 Nov 2016 09:10:19 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <1478189400-14606-2-git-send-email-yuanhan.liu@linux.intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Fri, 04 Nov 2016 08:10:21 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH 1/8] net/virtio: revert "virtio: fix restart" X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Nov 2016 08:10:22 -0000 On 11/03/2016 05:09 PM, Yuanhan Liu wrote: > This reverts commit 9a0615af7746 ("virtio: fix restart"); conflict is > manually addressed. > > Kyle reported an issue with above commit > > qemu-kvm: Guest moved used index from 5 to 1 > > with following steps, > > 1) Start my virtio interfaces > 2) Send some traffic into/out of the interfaces > 3) Stop the interfaces > 4) Start the interfaces > 5) Send some more traffic > > And here are some quotes from Kyle's analysis, > > Prior to the patch, if an interface were stopped then started, without > restarting the application, the queues would be left as-is, because > hw->started would be set to 1. Now, calling stop sets hw->started to 0, > which means the next call to start will "touch the queues". This is the > unintended side-effect that causes the problem. > > Fixes: 9a0615af7746 ("virtio: fix restart") > > Cc: Jianfeng Tan > Cc: > Reported-by: Kyle Larose > Signed-off-by: Yuanhan Liu Reviewed-by: Maxime Coquelin Thanks, Maxime