If the guest is connected but not servicing the virt queue, this leads to vhost send retries until timeout. This is fine in isolation but if there are other high rate queues also being serviced by the same PMD it can lead to a performance hit on those queues. Change to only retry when at least some packets have been successfully sent on the previous attempt.
Reported-by: Bhanuprakash Bodireddy <[email protected]> Signed-off-by: Kevin Traynor <[email protected]> --- Sending for discussion in this mailing list thread http://openvswitch.org/pipermail/dev/2016-May/071115.html lib/netdev-dpdk.c | 28 +--------------------------- 1 files changed, 1 insertions(+), 27 deletions(-) diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c index c7217ea..c39ce6c 100644 --- a/lib/netdev-dpdk.c +++ b/lib/netdev-dpdk.c @@ -110,11 +110,6 @@ BUILD_ASSERT_DECL((MAX_NB_MBUF / ROUND_DOWN_POW2(MAX_NB_MBUF/MIN_NB_MBUF)) static char *cuse_dev_name = NULL; /* Character device cuse_dev_name. */ static char *vhost_sock_dir = NULL; /* Location of vhost-user sockets */ -/* - * Maximum amount of time in micro seconds to try and enqueue to vhost. - */ -#define VHOST_ENQ_RETRY_USECS 100 - static const struct rte_eth_conf port_conf = { .rxmode = { .mq_mode = ETH_MQ_RX_RSS, @@ -1261,7 +1256,6 @@ __netdev_dpdk_vhost_send(struct netdev *netdev, int qid, struct rte_mbuf **cur_pkts = (struct rte_mbuf **) pkts; unsigned int total_pkts = cnt; unsigned int qos_pkts = cnt; - uint64_t start = 0; qid = dev->tx_q[qid % dev->real_n_txq].map; @@ -1290,27 +1284,7 @@ __netdev_dpdk_vhost_send(struct netdev *netdev, int qid, /* Prepare for possible next iteration.*/ cur_pkts = &cur_pkts[tx_pkts]; } else { - uint64_t timeout = VHOST_ENQ_RETRY_USECS * rte_get_timer_hz() / 1E6; - unsigned int expired = 0; - - if (!start) { - start = rte_get_timer_cycles(); - } - - /* - * Unable to enqueue packets to vhost interface. - * Check available entries before retrying. - */ - while (!rte_vring_available_entries(virtio_dev, vhost_qid)) { - if (OVS_UNLIKELY((rte_get_timer_cycles() - start) > timeout)) { - expired = 1; - break; - } - } - if (expired) { - /* break out of main loop. */ - break; - } + break; } } while (cnt); -- 1.7.4.1 _______________________________________________ dev mailing list [email protected] http://openvswitch.org/mailman/listinfo/dev
