Commit a8cc21f6 authored by Krishna Kumar's avatar Krishna Kumar Committed by Jeff Garzik
Browse files

Optimize cxgb3 xmit path (a bit) 



	1. Add common code for stopping queue.
	2. No need to call netif_stop_queue followed by netif_wake_queue (and
	   infact a netif_start_queue could have been used instead), instead
	   call stop_queue if required, and remove code under USE_GTS macro.
	3. There is no need to check for netif_queue_stopped, as the network
	   core guarantees that for us (I am sure every driver could remove
	   that check, eg e1000 - I have tested that path a few billion times
	   with about a few hundred thousand qstops but the condition never
	   hit even once).

Signed-off-by: default avatarKrishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent 3c34ac36

drivers/net/cxgb3/sge.c

+15 −20
Original line number Diff line number Diff line
@@ -1059,6 +1059,14 @@ static void write_tx_pkt_wr(struct adapter *adap, struct sk_buff *skb, 
			 htonl(V_WR_TID(q->token)));

}



static inline void t3_stop_queue(struct net_device *dev, struct sge_qset *qs,

				 struct sge_txq *q)

{

	netif_stop_queue(dev);

	set_bit(TXQ_ETH, &qs->txq_stopped);

	q->stops++;

}



/**

 *	eth_xmit - add a packet to the Ethernet Tx queue

 *	@skb: the packet
@@ -1090,31 +1098,18 @@ int t3_eth_xmit(struct sk_buff *skb, struct net_device *dev) 
	ndesc = calc_tx_descs(skb);



	if (unlikely(credits < ndesc)) {

		if (!netif_queue_stopped(dev)) {

			netif_stop_queue(dev);

			set_bit(TXQ_ETH, &qs->txq_stopped);

			q->stops++;

		t3_stop_queue(dev, qs, q);

		dev_err(&adap->pdev->dev,

			"%s: Tx ring %u full while queue awake!\n",

			dev->name, q->cntxt_id & 7);

		}

		spin_unlock(&q->lock);

		return NETDEV_TX_BUSY;

	}



	q->in_use += ndesc;

	if (unlikely(credits - ndesc < q->stop_thres)) {

		q->stops++;

		netif_stop_queue(dev);

		set_bit(TXQ_ETH, &qs->txq_stopped);

#if !USE_GTS

		if (should_restart_tx(q) &&

		    test_and_clear_bit(TXQ_ETH, &qs->txq_stopped)) {

			q->restarts++;

			netif_wake_queue(dev);

		}

#endif

	}

	if (unlikely(credits - ndesc < q->stop_thres))

		if (USE_GTS || !should_restart_tx(q))

			t3_stop_queue(dev, qs, q);



	gen = q->gen;

	q->unacked += ndesc;

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