From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [119.145.14.66]) by dpdk.org (Postfix) with ESMTP id B75245688 for ; Sat, 21 Mar 2015 02:30:59 +0100 (CET) Received: from 172.24.2.119 (EHLO szxeml433-hub.china.huawei.com) ([172.24.2.119]) by szxrg03-dlp.huawei.com (MOS 4.4.3-GA FastPath queued) with ESMTP id BDK85494; Sat, 21 Mar 2015 09:30:57 +0800 (CST) Received: from [127.0.0.1] (10.177.19.115) by szxeml433-hub.china.huawei.com (10.82.67.210) with Microsoft SMTP Server id 14.3.158.1; Sat, 21 Mar 2015 09:30:52 +0800 Message-ID: <550CC9CA.7000807@huawei.com> Date: Sat, 21 Mar 2015 09:30:50 +0800 From: Linhaifeng User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:31.0) Gecko/20100101 Thunderbird/31.1.0 MIME-Version: 1.0 To: "Xie, Huawei" , "dev@dpdk.org" References: <1426848383-15764-1-git-send-email-haifeng.lin@huawei.com> In-Reply-To: Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.19.115] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020201.550CC9D1.00F4, ss=1, re=0.001, recu=0.000, reip=0.000, cl=1, cld=1, fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: b0153c9615295b4dce75111426321e59 Subject: Re: [dpdk-dev] [PATCH] lib/librte_pmd_virtio fix can't receive packets after rx_q is empty 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: Sat, 21 Mar 2015 01:31:01 -0000 On 2015/3/21 0:54, Xie, Huawei wrote: > On 3/20/2015 6:47 PM, linhaifeng wrote: >> From: Linhaifeng >> >> If failed to alloc mbuf ring_size times the rx_q may be empty and can't >> receive any packets forever because nb_used is 0 forever. > Agreed. In current implementation, once VQ becomes empty, we have no > chance to refill it again. > The simple fix is, receive one and then refill one as other PMDs. Need > to consider which is best strategy in terms of performance in future. > How did you find this? through code review or real workload? We found this through real workload which use vhost_net + virtio_pmd to forward packets in VM. >> so we should try to refill when nb_used is 0.After otherone free mbuf >> we can restart to receive packets. >> >> Signed-off-by: Linhaifeng >> --- >> lib/librte_pmd_virtio/virtio_rxtx.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/lib/librte_pmd_virtio/virtio_rxtx.c b/lib/librte_pmd_virtio/virtio_rxtx.c >> index 1d74b34..5c7e0cd 100644 >> --- a/lib/librte_pmd_virtio/virtio_rxtx.c >> +++ b/lib/librte_pmd_virtio/virtio_rxtx.c >> @@ -495,7 +495,7 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts) >> num = num - ((rxvq->vq_used_cons_idx + num) % DESC_PER_CACHELINE); >> >> if (num == 0) >> - return 0; >> + goto refill; >> >> num = virtqueue_dequeue_burst_rx(rxvq, rcv_pkts, len, num); >> PMD_RX_LOG(DEBUG, "used:%d dequeue:%d", nb_used, num); >> @@ -536,6 +536,7 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts) >> >> rxvq->packets += nb_rx; >> >> +refill: >> /* Allocate new mbuf for the used descriptor */ >> error = ENOSPC; >> while (likely(!virtqueue_full(rxvq))) { > > > -- Regards, Haifeng