This commit introduces netdev_dpdk_eth_tx_queue() function that implements intermediate queue and packet buffering. The packets get buffered till the threshold 'INTERIM_QUEUE_BURST_THRESHOLD[32] is reached and eventually gets transmitted.
To handle the case(eg: ping) where packets get stuck in the queue at low rates, drain logic is implemented and gets invoked from dp_netdev_drain_txq_ports() as part of PMD packet processing loop. Signed-off-by: Bhanuprakash Bodireddy <[email protected]> Signed-off-by: Antonio Fischetti <[email protected]> Co-authored-by: Antonio Fischetti <[email protected]> Signed-off-by: Markus Magnusson <[email protected]> Co-authored-by: Markus Magnusson <[email protected]> --- lib/dpif-netdev.c | 44 +++++++++++++++++++++++++++++++++++++++++++- lib/netdev-dpdk.c | 35 ++++++++++++++++++++++++++++++++++- 2 files changed, 77 insertions(+), 2 deletions(-) diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c index 2f224db..e1c43fe 100644 --- a/lib/dpif-netdev.c +++ b/lib/dpif-netdev.c @@ -332,6 +332,7 @@ enum pmd_cycles_counter_type { }; #define XPS_TIMEOUT_MS 500LL +#define LAST_USED_QID_NONE -1 /* Contained by struct dp_netdev_port's 'rxqs' member. */ struct dp_netdev_rxq { @@ -492,7 +493,13 @@ struct rxq_poll { struct tx_port { struct dp_netdev_port *port; int qid; - long long last_used; + int last_used_qid; /* Last queue id where packets got + enqueued. */ + long long last_used; /* In case XPS is enabled, it contains the + * timestamp of the last time the port was + * used by the thread to send data. After + * XPS_TIMEOUT_MS elapses the qid will be + * marked as -1. */ struct hmap_node node; }; @@ -3080,6 +3087,25 @@ cycles_count_end(struct dp_netdev_pmd_thread *pmd, } static void +dp_netdev_drain_txq_ports(struct dp_netdev_pmd_thread *pmd) +{ + struct tx_port *cached_tx_port; + int tx_qid; + + HMAP_FOR_EACH (cached_tx_port, node, &pmd->send_port_cache) { + tx_qid = cached_tx_port->last_used_qid; + + if (tx_qid != LAST_USED_QID_NONE) { + netdev_txq_drain(cached_tx_port->port->netdev, tx_qid, + cached_tx_port->port->dynamic_txqs); + + /* Queue drained and mark it empty. */ + cached_tx_port->last_used_qid = LAST_USED_QID_NONE; + } + } +} + +static void dp_netdev_process_rxq_port(struct dp_netdev_pmd_thread *pmd, struct netdev_rxq *rx, odp_port_t port_no) @@ -4355,6 +4381,7 @@ dp_netdev_add_port_tx_to_pmd(struct dp_netdev_pmd_thread *pmd, tx->port = port; tx->qid = -1; + tx->last_used_qid = LAST_USED_QID_NONE; hmap_insert(&pmd->tx_ports, &tx->node, hash_port_no(tx->port->port_no)); pmd->need_reload = true; @@ -4925,6 +4952,14 @@ dpif_netdev_xps_get_tx_qid(const struct dp_netdev_pmd_thread *pmd, dpif_netdev_xps_revalidate_pmd(pmd, now, false); + /* The tx queue can change in XPS case, make sure packets in previous + * queue is drained properly. */ + if (tx->last_used_qid != LAST_USED_QID_NONE && + tx->qid != tx->last_used_qid) { + netdev_txq_drain(port->netdev, tx->last_used_qid, port->dynamic_txqs); + tx->last_used_qid = LAST_USED_QID_NONE; + } + VLOG_DBG("Core %d: New TX queue ID %d for port \'%s\'.", pmd->core_id, tx->qid, netdev_get_name(tx->port->netdev)); return min_qid; @@ -5020,6 +5055,13 @@ dp_execute_cb(void *aux_, struct dp_packet_batch *packets_, tx_qid = pmd->static_tx_qid; } + /* In case these packets gets buffered into an intermediate + * queue and XPS is enabled the drain function could find a + * different tx qid assigned to its thread. We keep track + * of the qid we're now using, that will trigger the drain + * function and will select the right queue to flush. */ + p->last_used_qid = tx_qid; + netdev_send(p->port->netdev, tx_qid, packets_, may_steal, dynamic_txqs); return; diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c index 13b4487..4a9d9aa 100644 --- a/lib/netdev-dpdk.c +++ b/lib/netdev-dpdk.c @@ -1429,6 +1429,7 @@ static inline int netdev_dpdk_eth_tx_burst(struct netdev_dpdk *dev, int qid, struct rte_mbuf **pkts, int cnt) { + struct dpdk_tx_queue *txq = &dev->tx_q[qid]; uint32_t nb_tx = 0; while (nb_tx != cnt) { @@ -1452,6 +1453,7 @@ netdev_dpdk_eth_tx_burst(struct netdev_dpdk *dev, int qid, } } + txq->count = 0; return cnt - nb_tx; } @@ -1836,6 +1838,37 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet_batch *batch) } } +/* Enqueue packets in an intermediate queue and call the drain + * function when the queue is full. This way we can amortize the + * cost of MMIO writes. */ +static inline int +netdev_dpdk_eth_tx_queue(struct netdev_dpdk *dev, int qid, + struct rte_mbuf **pkts, int cnt) +{ + struct dpdk_tx_queue *txq = &dev->tx_q[qid]; + + int i = 0; + int dropped = 0; + + while (i < cnt) { + int freeslots = INTERIM_QUEUE_BURST_THRESHOLD - txq->count; + int tocopy = MIN(freeslots, cnt-i); + + memcpy(&txq->burst_pkts[txq->count], &pkts[i], + tocopy * sizeof (struct rte_mbuf *)); + + txq->count += tocopy; + i += tocopy; + + /* Queue full, burst the packets */ + if (txq->count >= INTERIM_QUEUE_BURST_THRESHOLD) { + dropped += netdev_dpdk_eth_tx_burst(dev, qid, txq->burst_pkts, + txq->count); + } + } + return dropped; +} + static int netdev_dpdk_vhost_send(struct netdev *netdev, int qid, struct dp_packet_batch *batch, @@ -1884,7 +1917,7 @@ netdev_dpdk_send__(struct netdev_dpdk *dev, int qid, cnt = netdev_dpdk_qos_run(dev, pkts, cnt); dropped = batch->count - cnt; - dropped += netdev_dpdk_eth_tx_burst(dev, qid, pkts, cnt); + dropped += netdev_dpdk_eth_tx_queue(dev, qid, pkts, cnt); if (OVS_UNLIKELY(dropped)) { rte_spinlock_lock(&dev->stats_lock); -- 2.4.11 _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
