cxgbe: use trylock in Tx callback instead of spinning for a lock

CXGBE PMD depends on an alarm to periodically transmit any pending
coalesced packets and hence spins for a lock for each tx queue in the
alarm callback.

A better solution is to try to get a lock whenever possible, instead
of spinning for it.

Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Kumar Sanghvi <kumaras@chelsio.com>

diff --git a/drivers/net/cxgbe/base/adapter.h b/drivers/net/cxgbe/base/adapter.h
index a1e8ef7..a5225c0 100644 (file)
--- a/drivers/net/cxgbe/base/adapter.h
+++ b/drivers/net/cxgbe/base/adapter.h
@@ -472,6 +472,15 @@ static inline void t4_os_unlock(rte_spinlock_t *lock)
        rte_spinlock_unlock(lock);
 }
 
+/**
+ * t4_os_trylock - try to get a lock
+ * @lock: the spinlock
+ */
+static inline int t4_os_trylock(rte_spinlock_t *lock)
+{
+       return rte_spinlock_trylock(lock);
+}
+
 /**
  * t4_os_init_list_head - initialize
  * @head: head of list to initialize [to empty]

diff --git a/drivers/net/cxgbe/sge.c b/drivers/net/cxgbe/sge.c
index aa0c2e5..51449e0 100644 (file)
--- a/drivers/net/cxgbe/sge.c
+++ b/drivers/net/cxgbe/sge.c
@@ -808,20 +808,23 @@ static void tx_timer_cb(void *data)
        struct adapter *adap = (struct adapter *)data;
        struct sge_eth_txq *txq = &adap->sge.ethtxq[0];
        int i;
+       unsigned int coal_idx;
 
        /* monitor any pending tx */
        for (i = 0; i < adap->sge.max_ethqsets; i++, txq++) {
-               t4_os_lock(&txq->txq_lock);
-               if (txq->q.coalesce.idx) {
-                       if (txq->q.coalesce.idx == txq->q.last_coal_idx &&
-                           txq->q.pidx == txq->q.last_pidx) {
-                               ship_tx_pkt_coalesce_wr(adap, txq);
-                       } else {
-                               txq->q.last_coal_idx = txq->q.coalesce.idx;
-                               txq->q.last_pidx = txq->q.pidx;
+               if (t4_os_trylock(&txq->txq_lock)) {
+                       coal_idx = txq->q.coalesce.idx;
+                       if (coal_idx) {
+                               if (coal_idx == txq->q.last_coal_idx &&
+                                   txq->q.pidx == txq->q.last_pidx) {
+                                       ship_tx_pkt_coalesce_wr(adap, txq);
+                               } else {
+                                       txq->q.last_coal_idx = coal_idx;
+                                       txq->q.last_pidx = txq->q.pidx;
+                               }
                        }
+                       t4_os_unlock(&txq->txq_lock);
                }
-               t4_os_unlock(&txq->txq_lock);
        }
        rte_eal_alarm_set(50, tx_timer_cb, (void *)adap);
 }