From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id B36AE58D7 for ; Wed, 15 Oct 2014 05:03:25 +0200 (CEST) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP; 14 Oct 2014 20:11:11 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,721,1406617200"; d="scan'208";a="605507979" Received: from shvmail01.sh.intel.com ([10.239.29.42]) by fmsmga001.fm.intel.com with ESMTP; 14 Oct 2014 20:11:08 -0700 Received: from shecgisg004.sh.intel.com (shecgisg004.sh.intel.com [10.239.29.89]) by shvmail01.sh.intel.com with ESMTP id s9F3B5hu011075; Wed, 15 Oct 2014 11:11:05 +0800 Received: from shecgisg004.sh.intel.com (localhost [127.0.0.1]) by shecgisg004.sh.intel.com (8.13.6/8.13.6/SuSE Linux 0.8) with ESMTP id s9F3B3YE017928; Wed, 15 Oct 2014 11:11:05 +0800 Received: (from couyang@localhost) by shecgisg004.sh.intel.com (8.13.6/8.13.6/Submit) id s9F3B3RF017924; Wed, 15 Oct 2014 11:11:03 +0800 From: Ouyang Changchun To: dev@dpdk.org Date: Wed, 15 Oct 2014 11:11:00 +0800 Message-Id: <1413342660-17894-1-git-send-email-changchun.ouyang@intel.com> X-Mailer: git-send-email 1.7.12.2 In-Reply-To: <1413302634-848-1-git-send-email-changchun.ouyang@intel.com> References: <1413302634-848-1-git-send-email-changchun.ouyang@intel.com> Subject: [dpdk-dev] [PATCH v5] virtio: Fix vring entry number issue 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: Wed, 15 Oct 2014 03:03:26 -0000 Fix one issue in virtio TX: it needs one more vring descriptor to hold the virtio header when transmitting packets, it is used later to determine whether to free more entries from used vring. It fixes failing to transmit any packet with 1 segment in the circumstance of only 1 descriptor in the vring free list. Signed-off-by: Changchun Ouyang Reviewed-by: Olivier Matz --- -V5 change: Use 'likely' to hint compiler to generate favorable codes. -V4 change: Relocate those changelog and annotation here. -V3 change: Resolve compilation issue due to mbuf re-structure. -V2 change: Refine description, 'vring descriptor' is more accurate than 'vring entry'; Accordingly update test condition (it needs one more descriptor for virtio header) to put packets to transmit queue. -V1 change: Fix the vring descriptor issue in virtio TX, it needs one more vring descriptor to hold the virtio header. lib/librte_pmd_virtio/virtio_rxtx.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/librte_pmd_virtio/virtio_rxtx.c b/lib/librte_pmd_virtio/virtio_rxtx.c index ad6401c..3f6bad2 100644 --- a/lib/librte_pmd_virtio/virtio_rxtx.c +++ b/lib/librte_pmd_virtio/virtio_rxtx.c @@ -699,7 +699,8 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts) num = (uint16_t)(likely(nb_used < VIRTIO_MBUF_BURST_SZ) ? nb_used : VIRTIO_MBUF_BURST_SZ); while (nb_tx < nb_pkts) { - int need = tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt; + /* Need one more descriptor for virtio header. */ + int need = tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt + 1; int deq_cnt = RTE_MIN(need, (int)num); num -= (deq_cnt > 0) ? deq_cnt : 0; @@ -708,7 +709,12 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts) deq_cnt--; } - if (tx_pkts[nb_tx]->nb_segs <= txvq->vq_free_cnt) { + need = (int)tx_pkts[nb_tx]->nb_segs - txvq->vq_free_cnt + 1; + /* + * Zero or negative value indicates it has enough free + * descriptors to use for transmitting. + */ + if (likely(need <= 0)) { txm = tx_pkts[nb_tx]; /* Enqueue Packet buffers */ error = virtqueue_enqueue_xmit(txvq, txm); -- 1.8.4.2