From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linhaifeng Subject: Re: [PATCH] lib/librte_pmd_virtio fix can't receive packets after rx_q is empty Date: Sat, 21 Mar 2015 09:30:50 +0800 Message-ID: <550CC9CA.7000807@huawei.com> References: <1426848383-15764-1-git-send-email-haifeng.lin@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit To: "Xie, Huawei" , "dev-VfR2kkLFssw@public.gmane.org" Return-path: In-Reply-To: List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 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