>
> 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 are sent at low rate and
> can potentially get stuck in the queue, flush logic is implemented
> that gets invoked from dp_netdev_flush_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]>
> Acked-by: Eelco Chaudron <[email protected]>
> ---
> lib/dpif-netdev.c | 44
>+++++++++++++++++++++++++++++++++++++++++++-
> lib/netdev-dpdk.c | 37 +++++++++++++++++++++++++++++++++++--
> 2 files changed, 78 insertions(+), 3 deletions(-)
>
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index 4e29085..7e1f5bc 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_flush_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_flush(cached_tx_port->port->netdev, tx_qid,
> + cached_tx_port->port->dynamic_txqs);
> +
> + /* Queue flushed and mark it empty. */
> + cached_tx_port->last_used_qid = LAST_USED_QID_NONE;
> + }
> + }
> +}
> +
>
>Could you move this function and I think the other code in dpif-netdev.c to
>patch 6, if you can ?
Should be a simple change. Will do this.
>This function is unused, so will generate a build error with –Werror when
>applied in sequence and logically this seems like it can go into patch 6.
Completely agree.
- Bhanuprakash.
>
>Darrell
>
>
> +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 flushed properly. */
> + if (tx->last_used_qid != LAST_USED_QID_NONE &&
> + tx->qid != tx->last_used_qid) {
> + netdev_txq_flush(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 flush 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 flush
> + * 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 51d528d..99ad8c7 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -1444,6 +1444,7 @@ 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) {
> @@ -1467,6 +1468,7 @@ netdev_dpdk_eth_tx_burst(struct netdev_dpdk
>*dev, int qid,
> }
> }
>
> + txq->dpdk_pkt_cnt = 0;
> return cnt - nb_tx;
> }
>
> @@ -1866,6 +1868,37 @@ out:
> }
> }
>
> +/* Enqueue packets in an intermediate queue and call the flush
> + * 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-
>>dpdk_pkt_cnt;
> + int tocopy = MIN(freeslots, cnt-i);
> +
> + memcpy(&txq->dpdk_burst_pkts[txq->dpdk_pkt_cnt], &pkts[i],
> + tocopy * sizeof (struct rte_mbuf *));
> +
> + txq->dpdk_pkt_cnt += tocopy;
> + i += tocopy;
> +
> + /* Queue full, burst the packets. */
> + if (txq->dpdk_pkt_cnt >= INTERIM_QUEUE_BURST_THRESHOLD) {
> + dropped += netdev_dpdk_eth_tx_burst(dev, qid, txq-
>>dpdk_burst_pkts,
> + txq->dpdk_pkt_cnt);
> + }
> + }
> + return dropped;
> +}
> +
> /* Tx function. Transmit packets indefinitely */
> static void
> dpdk_do_tx_copy(struct netdev *netdev, int qid, struct dp_packet_batch
>*batch)
> @@ -1923,7 +1956,7 @@ dpdk_do_tx_copy(struct netdev *netdev, int qid,
>struct dp_packet_batch *batch)
> newcnt = netdev_dpdk_qos_run(dev, pkts, newcnt);
>
> dropped += qos_pkts - newcnt;
> - dropped += netdev_dpdk_eth_tx_burst(dev, qid, pkts, newcnt);
> + dropped += netdev_dpdk_eth_tx_queue(dev, qid, pkts, newcnt);
> }
>
> if (OVS_UNLIKELY(dropped)) {
> @@ -1981,7 +2014,7 @@ 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
>
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