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 785222BAA for ; Fri, 24 Feb 2017 12:08:58 +0100 (CET) Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (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 D84A6326BB; Fri, 24 Feb 2017 11:08:58 +0000 (UTC) Received: from ktraynor.remote.csb (ovpn-117-111.ams2.redhat.com [10.36.117.111]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v1OB8v47007209; Fri, 24 Feb 2017 06:08:57 -0500 To: Zhiyong Yang , dev@dpdk.org References: <1487926101-4637-1-git-send-email-zhiyong.yang@intel.com> <1487926101-4637-5-git-send-email-zhiyong.yang@intel.com> Cc: yuanhan.liu@linux.intel.com, maxime.coquelin@redhat.com From: Kevin Traynor Organization: Red Hat Message-ID: <22266556-4d0e-5db1-6a90-eebcecbe5283@redhat.com> Date: Fri, 24 Feb 2017 11:08:56 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1487926101-4637-5-git-send-email-zhiyong.yang@intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 24 Feb 2017 11:08:58 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH 4/5] net/vhost: remove limit of vhost TX burst size X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 24 Feb 2017 11:08:58 -0000 On 02/24/2017 08:48 AM, Zhiyong Yang wrote: > vhost removes limit of TX burst size(32 pkts) and supports to make > an best effort to transmit pkts. > > Cc: yuanhan.liu@linux.intel.com > Cc: maxime.coquelin@redhat.com > > Signed-off-by: Zhiyong Yang > --- > drivers/net/vhost/rte_eth_vhost.c | 24 ++++++++++++++++++++++-- > 1 file changed, 22 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c > index e98cffd..1e1fa34 100644 > --- a/drivers/net/vhost/rte_eth_vhost.c > +++ b/drivers/net/vhost/rte_eth_vhost.c > @@ -52,6 +52,7 @@ > #define ETH_VHOST_QUEUES_ARG "queues" > #define ETH_VHOST_CLIENT_ARG "client" > #define ETH_VHOST_DEQUEUE_ZERO_COPY "dequeue-zero-copy" > +#define VHOST_MAX_PKT_BURST 32 > > static const char *valid_arguments[] = { > ETH_VHOST_IFACE_ARG, > @@ -434,8 +435,27 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs) > goto out; > > /* Enqueue packets to guest RX queue */ > - nb_tx = rte_vhost_enqueue_burst(r->vid, > - r->virtqueue_id, bufs, nb_bufs); > + if (likely(nb_bufs <= VHOST_MAX_PKT_BURST)) > + nb_tx = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id, > + bufs, nb_bufs); > + else { > + uint16_t nb_send = nb_bufs; > + > + while (nb_send) { > + uint16_t nb_pkts; > + uint16_t num = (uint16_t)RTE_MIN(nb_send, > + VHOST_MAX_PKT_BURST); > + > + nb_pkts = rte_vhost_enqueue_burst(r->vid, > + r->virtqueue_id, > + &bufs[nb_tx], num); > + > + nb_tx += nb_pkts; > + nb_send -= nb_pkts; > + if (nb_pkts < num) > + break; > + } In the code above, - if the VM does not service the queue, this will spin forever - if the queue is almost full, it will be very slow In the example of OVS, other ports being serviced by the same core would stop being serviced or drop a lot of packets. If you want to remove the 32 pkt limitation, the rte_vhost_enqueue_burst() api limitation needs to be changed first. It doesn't make sense to put retry code in eth_vhost_tx() fn, the application can retry if it wants to. > + } > > r->stats.pkts += nb_tx; > r->stats.missed_pkts += nb_bufs - nb_tx; >