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 8D6E12BCD for ; Mon, 26 Sep 2016 23:05:19 +0200 (CEST) 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 E5DA6636FD; Mon, 26 Sep 2016 21:05:18 +0000 (UTC) Received: from [10.36.4.83] (vpn1-4-83.ams2.redhat.com [10.36.4.83]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u8QL5Ghk027184 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 26 Sep 2016 17:05:18 -0400 To: Yuanhan Liu , dev@dpdk.org References: <1471939839-29778-1-git-send-email-yuanhan.liu@linux.intel.com> <1474604007-5221-1-git-send-email-yuanhan.liu@linux.intel.com> <1474604007-5221-7-git-send-email-yuanhan.liu@linux.intel.com> From: Maxime Coquelin Message-ID: <96a4b7a4-ee4d-6253-fe6e-7474089e07d4@redhat.com> Date: Mon, 26 Sep 2016 23:05:16 +0200 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: <1474604007-5221-7-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 [10.5.110.39]); Mon, 26 Sep 2016 21:05:18 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH v2 6/7] examples/vhost: add an option to enable dequeue zero copy 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: Mon, 26 Sep 2016 21:05:19 -0000 On 09/23/2016 06:13 AM, Yuanhan Liu wrote: > Add an option, --dequeue-zero-copy, to enable dequeue zero copy. > > One thing worth noting while using dequeue zero copy is the nb_tx_desc > has to be small enough so that the eth driver will hit the mbuf free > threshold easily and thus free mbuf more frequently. > > The reason behind that is, when dequeue zero copy is enabled, guest Tx > used vring will be updated only when corresponding mbuf is freed. If mbuf > is not freed frequently, the guest Tx vring could be starved. > > Signed-off-by: Yuanhan Liu > --- > examples/vhost/main.c | 19 ++++++++++++++++++- > 1 file changed, 18 insertions(+), 1 deletion(-) Reviewed-by: Maxime Coquelin Thanks, Maxime