drain_eth_rx() uses rte_vhost_avail_entries() to calculate the available entries to determine if a retry is required. However, this function only works with split rings, and calculating packed rings will return the wrong value and cause unnecessary retries resulting in a significant performance penalty.
This patch uses the difference between tx burst and rx burst as a retry condition, and introduces enqueue_pkts() to reduce code duplication. Fixes: 4ecf22e356 ("vhost: export device id as the interface to applications") Cc: sta...@dpdk.org Signed-off-by: Yuan Wang <yuanx.w...@intel.com> --- examples/vhost/main.c | 78 ++++++++++++++++++------------------------- 1 file changed, 32 insertions(+), 46 deletions(-) diff --git a/examples/vhost/main.c b/examples/vhost/main.c index c4d46de1c5..198bf9dc4a 100644 --- a/examples/vhost/main.c +++ b/examples/vhost/main.c @@ -599,7 +599,7 @@ us_vhost_usage(const char *prgname) { RTE_LOG(INFO, VHOST_CONFIG, "%s [EAL options] -- -p PORTMASK\n" " --vm2vm [0|1|2]\n" - " --rx_retry [0|1] --mergeable [0|1] --stats [0-N]\n" + " --rx-retry [0|1] --mergeable [0|1] --stats [0-N]\n" " --socket-file <path>\n" " --nb-devices ND\n" " -p PORTMASK: Set mask for ports to be used by application\n" @@ -1021,31 +1021,43 @@ sync_virtio_xmit(struct vhost_dev *dst_vdev, struct vhost_dev *src_vdev, } } -static __rte_always_inline void -drain_vhost(struct vhost_dev *vdev) +static __rte_always_inline uint16_t +enqueue_pkts(struct vhost_dev *vdev, struct rte_mbuf **pkts, uint16_t rx_count) { - uint16_t ret; - uint32_t buff_idx = rte_lcore_id() * RTE_MAX_VHOST_DEVICE + vdev->vid; - uint16_t nr_xmit = vhost_txbuff[buff_idx]->len; - struct rte_mbuf **m = vhost_txbuff[buff_idx]->m_table; + uint16_t enqueue_count; if (builtin_net_driver) { - ret = vs_enqueue_pkts(vdev, VIRTIO_RXQ, m, nr_xmit); + enqueue_count = vs_enqueue_pkts(vdev, VIRTIO_RXQ, pkts, rx_count); } else if (dma_bind[vdev->vid].dmas[VIRTIO_RXQ].async_enabled) { uint16_t enqueue_fail = 0; int16_t dma_id = dma_bind[vdev->vid].dmas[VIRTIO_RXQ].dev_id; complete_async_pkts(vdev); - ret = rte_vhost_submit_enqueue_burst(vdev->vid, VIRTIO_RXQ, m, nr_xmit, dma_id, 0); + enqueue_count = rte_vhost_submit_enqueue_burst(vdev->vid, + VIRTIO_RXQ, pkts, rx_count, dma_id, 0); - enqueue_fail = nr_xmit - ret; + enqueue_fail = rx_count - enqueue_count; if (enqueue_fail) - free_pkts(&m[ret], nr_xmit - ret); + free_pkts(&pkts[enqueue_count], enqueue_fail); + } else { - ret = rte_vhost_enqueue_burst(vdev->vid, VIRTIO_RXQ, - m, nr_xmit); + enqueue_count = rte_vhost_enqueue_burst(vdev->vid, VIRTIO_RXQ, + pkts, rx_count); } + return enqueue_count; +} + +static __rte_always_inline void +drain_vhost(struct vhost_dev *vdev) +{ + uint16_t ret; + uint32_t buff_idx = rte_lcore_id() * RTE_MAX_VHOST_DEVICE + vdev->vid; + uint16_t nr_xmit = vhost_txbuff[buff_idx]->len; + struct rte_mbuf **m = vhost_txbuff[buff_idx]->m_table; + + ret = enqueue_pkts(vdev, m, nr_xmit); + if (enable_stats) { __atomic_add_fetch(&vdev->stats.rx_total_atomic, nr_xmit, __ATOMIC_SEQ_CST); @@ -1337,44 +1349,18 @@ drain_eth_rx(struct vhost_dev *vdev) if (!rx_count) return; - /* - * When "enable_retry" is set, here we wait and retry when there - * is no enough free slots in the queue to hold @rx_count packets, - * to diminish packet loss. - */ - if (enable_retry && - unlikely(rx_count > rte_vhost_avail_entries(vdev->vid, - VIRTIO_RXQ))) { - uint32_t retry; + enqueue_count = enqueue_pkts(vdev, pkts, rx_count); - for (retry = 0; retry < burst_rx_retry_num; retry++) { + /* Retry if necessary */ + if (unlikely(enqueue_count < rx_count) && enable_retry) { + uint32_t retry = 0; + + while (enqueue_count < rx_count && retry++ < burst_rx_retry_num) { rte_delay_us(burst_rx_delay_time); - if (rx_count <= rte_vhost_avail_entries(vdev->vid, - VIRTIO_RXQ)) - break; + enqueue_count += enqueue_pkts(vdev, pkts, rx_count - enqueue_count); } } - if (builtin_net_driver) { - enqueue_count = vs_enqueue_pkts(vdev, VIRTIO_RXQ, - pkts, rx_count); - } else if (dma_bind[vdev->vid].dmas[VIRTIO_RXQ].async_enabled) { - uint16_t enqueue_fail = 0; - int16_t dma_id = dma_bind[vdev->vid].dmas[VIRTIO_RXQ].dev_id; - - complete_async_pkts(vdev); - enqueue_count = rte_vhost_submit_enqueue_burst(vdev->vid, - VIRTIO_RXQ, pkts, rx_count, dma_id, 0); - - enqueue_fail = rx_count - enqueue_count; - if (enqueue_fail) - free_pkts(&pkts[enqueue_count], enqueue_fail); - - } else { - enqueue_count = rte_vhost_enqueue_burst(vdev->vid, VIRTIO_RXQ, - pkts, rx_count); - } - if (enable_stats) { __atomic_add_fetch(&vdev->stats.rx_total_atomic, rx_count, __ATOMIC_SEQ_CST); -- 2.25.1