[TG3]: Minimize locking in TX path.
This is similar to Eric Dumazet's tx_lock patch for tg3 but takes it
one step further to eliminate the tx_lock in the tx_completion path
when the tx queue is not stopped.
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index af8263a..e877579 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -121,12 +121,9 @@
TG3_RX_RCB_RING_SIZE(tp))
#define TG3_TX_RING_BYTES (sizeof(struct tg3_tx_buffer_desc) * \
TG3_TX_RING_SIZE)
-#define TX_RING_GAP(TP) \
- (TG3_TX_RING_SIZE - (TP)->tx_pending)
#define TX_BUFFS_AVAIL(TP) \
- (((TP)->tx_cons <= (TP)->tx_prod) ? \
- (TP)->tx_cons + (TP)->tx_pending - (TP)->tx_prod : \
- (TP)->tx_cons - (TP)->tx_prod - TX_RING_GAP(TP))
+ ((TP)->tx_pending - \
+ (((TP)->tx_prod - (TP)->tx_cons) & (TG3_TX_RING_SIZE - 1)))
#define NEXT_TX(N) (((N) + 1) & (TG3_TX_RING_SIZE - 1))
#define RX_PKT_BUF_SZ (1536 + tp->rx_offset + 64)
@@ -2880,9 +2877,13 @@
tp->tx_cons = sw_idx;
- if (netif_queue_stopped(tp->dev) &&
- (TX_BUFFS_AVAIL(tp) > TG3_TX_WAKEUP_THRESH))
- netif_wake_queue(tp->dev);
+ if (unlikely(netif_queue_stopped(tp->dev))) {
+ spin_lock(&tp->tx_lock);
+ if (netif_queue_stopped(tp->dev) &&
+ (TX_BUFFS_AVAIL(tp) > TG3_TX_WAKEUP_THRESH))
+ netif_wake_queue(tp->dev);
+ spin_unlock(&tp->tx_lock);
+ }
}
/* Returns size of skb allocated or < 0 on error.
@@ -3198,9 +3199,7 @@
/* run TX completion thread */
if (sblk->idx[0].tx_consumer != tp->tx_cons) {
- spin_lock(&tp->tx_lock);
tg3_tx(tp);
- spin_unlock(&tp->tx_lock);
}
/* run RX thread, within the bounds set by NAPI.
@@ -3716,8 +3715,11 @@
tw32_tx_mbox((MAILBOX_SNDHOST_PROD_IDX_0 + TG3_64BIT_REG_LOW), entry);
tp->tx_prod = entry;
- if (TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1))
+ if (TX_BUFFS_AVAIL(tp) <= (MAX_SKB_FRAGS + 1)) {
netif_stop_queue(dev);
+ if (TX_BUFFS_AVAIL(tp) > TG3_TX_WAKEUP_THRESH)
+ netif_wake_queue(tp->dev);
+ }
out_unlock:
mmiowb();