From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH v2 1/2] virtio: fix queue size and number of descriptors Date: Mon, 20 Jul 2015 11:40:45 -0700 Message-ID: <1437417646-11221-2-git-send-email-stephen@networkplumber.org> References: <1437417646-11221-1-git-send-email-stephen@networkplumber.org> Cc: dev@dpdk.org To: changchun.ouyang@intel.com Return-path: Received: from mail-pd0-f170.google.com (mail-pd0-f170.google.com [209.85.192.170]) by dpdk.org (Postfix) with ESMTP id 3CD9FCE7 for ; Mon, 20 Jul 2015 20:40:38 +0200 (CEST) Received: by pdbnt7 with SMTP id nt7so34672326pdb.0 for ; Mon, 20 Jul 2015 11:40:37 -0700 (PDT) In-Reply-To: <1437417646-11221-1-git-send-email-stephen@networkplumber.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" The virtual queue ring size and the number of slots actually usable are separate parameters. In the most common environment (QEMU) the virtual queue ring size is 256, but some environments the ring maybe much larger. The ring size comes from the host and the driver must use the actual size passed. The number of descriptors can be either zero to use the whole available ring, or some value smaller. This is used to limit the number of mbufs allocated for the receive ring. If more descriptors are requested than available the size is silently truncated. Note: the ring size (from host) must be a power of two, but the number of descriptors used can be any size from 1 to the size of the virtual ring. Reported-by: Ouyang Changchun Signed-off-by: Stephen Hemminger --- drivers/net/virtio/virtio_ethdev.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-) diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c index 9ca9bb2..d460d89 100644 --- a/drivers/net/virtio/virtio_ethdev.c +++ b/drivers/net/virtio/virtio_ethdev.c @@ -276,8 +276,6 @@ int virtio_dev_queue_setup(struct rte_eth_dev *dev, */ vq_size = VIRTIO_READ_REG_2(hw, VIRTIO_PCI_QUEUE_NUM); PMD_INIT_LOG(DEBUG, "vq_size: %d nb_desc:%d", vq_size, nb_desc); - if (nb_desc == 0) - nb_desc = vq_size; if (vq_size == 0) { PMD_INIT_LOG(ERR, "%s: virtqueue does not exist", __func__); return -EINVAL; @@ -288,16 +286,6 @@ int virtio_dev_queue_setup(struct rte_eth_dev *dev, return -EINVAL; } - if (nb_desc < vq_size) { - if (!rte_is_power_of_2(nb_desc)) { - PMD_INIT_LOG(ERR, - "nb_desc(%u) size is not powerof 2", - nb_desc); - return -EINVAL; - } - vq_size = nb_desc; - } - if (queue_type == VTNET_RQ) { snprintf(vq_name, sizeof(vq_name), "port%d_rvq%d", dev->data->port_id, queue_idx); @@ -325,7 +313,10 @@ int virtio_dev_queue_setup(struct rte_eth_dev *dev, vq->queue_id = queue_idx; vq->vq_queue_index = vtpci_queue_idx; vq->vq_nentries = vq_size; - vq->vq_free_cnt = vq_size; + + if (nb_desc == 0 || nb_desc > vq_size) + nb_desc = vq_size; + vq->vq_free_cnt = nb_desc; /* * Reserve a memzone for vring elements -- 2.1.4