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Message-Id: <20080130070016.29078.94125.sendpatchset@N20wks267652wss.in.ibm.com>
Date: Wed, 30 Jan 2008 12:30:16 +0530
From: Krishna Kumar <krkumar2@...ibm.com>
To: jeff@...zik.org
Cc: netdev@...r.kernel.org, davem@...emloft.net,
Krishna Kumar <krkumar2@...ibm.com>
Subject: [PATCH] Optimize cxgb3 xmit path (a bit)
Changes:
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).
Thanks,
- KK
Signed-off-by: Krishna Kumar <krkumar2@...ibm.com>
---
sge.c | 35 +++++++++++++++--------------------
1 files changed, 15 insertions(+), 20 deletions(-)
diff -ruNp a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
--- a/drivers/net/cxgb3/sge.c 2008-01-30 11:42:39.000000000 +0530
+++ b/drivers/net/cxgb3/sge.c 2008-01-30 12:15:28.000000000 +0530
@@ -1059,6 +1059,14 @@ static void write_tx_pkt_wr(struct adapt
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, str
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++;
- dev_err(&adap->pdev->dev,
- "%s: Tx ring %u full while queue awake!\n",
- dev->name, q->cntxt_id & 7);
- }
+ 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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