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[ovs-dev,v4,3/5] netdev-dpdk: Add intermediate queue support.

Message ID 1502211976-76937-4-git-send-email-bhanuprakash.bodireddy@intel.com
State Rejected
Delegated to: Darrell Ball
Headers show

Commit Message

Bodireddy, Bhanuprakash Aug. 8, 2017, 5:06 p.m. UTC 
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.

Signed-off-by: Bhanuprakash Bodireddy <bhanuprakash.bodireddy@intel.com>
Signed-off-by: Antonio Fischetti <antonio.fischetti@intel.com>
Co-authored-by: Antonio Fischetti <antonio.fischetti@intel.com>
Signed-off-by: Markus Magnusson <markus.magnusson@ericsson.com>
Co-authored-by: Markus Magnusson <markus.magnusson@ericsson.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
---
 lib/netdev-dpdk.c | 37 +++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)
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Patch

diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index d3892fe..b4dc36a 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -1483,6 +1483,7 @@  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) {
@@ -1506,6 +1507,7 @@  netdev_dpdk_eth_tx_burst(struct netdev_dpdk *dev, int qid,
         }
     }
 
+    txq->dpdk_pkt_cnt = 0;
     return cnt - nb_tx;
 }
 
@@ -1905,6 +1907,37 @@  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)
@@ -1962,7 +1995,7 @@  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)) {
@@ -2020,7 +2053,7 @@  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);