netdev - Re: [PATCH] forcedeth: Stay in NAPI as long as there's work

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Message-ID: <20100428112528.01277670@nehalam>
Date:	Wed, 28 Apr 2010 11:25:28 -0700
From:	Stephen Hemminger <shemminger@...tta.com>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	Joe Perches <joe@...ches.com>, Tom Herbert <therbert@...gle.com>,
	netdev@...r.kernel.org, aabdulla@...dia.com, davem@...emloft.net
Subject: Re: [PATCH] forcedeth: Stay in NAPI as long as there's work

The following does the same thing without the extra overhead
of testing all the registers. It also handles the out of memory
case.

Compile tested only...

Signed-off-by: Stephen Hemminger <shemminger@...tta.com>

--- a/drivers/net/forcedeth.c	2010-04-28 11:14:29.784799317 -0700
+++ b/drivers/net/forcedeth.c	2010-04-28 11:23:53.254354744 -0700
@@ -3743,23 +3743,26 @@ static int nv_napi_poll(struct napi_stru
 	u8 __iomem *base = get_hwbase(dev);
 	unsigned long flags;
 	int retcode;
-	int tx_work, rx_work;
+	int rx_count, tx_work=0, rx_work=0;
 
-	if (!nv_optimized(np)) {
-		spin_lock_irqsave(&np->lock, flags);
-		tx_work = nv_tx_done(dev, np->tx_ring_size);
-		spin_unlock_irqrestore(&np->lock, flags);
+	do {
+		if (!nv_optimized(np)) {
+			spin_lock_irqsave(&np->lock, flags);
+			tx_work += nv_tx_done(dev, np->tx_ring_size);
+			spin_unlock_irqrestore(&np->lock, flags);
 
-		rx_work = nv_rx_process(dev, budget);
-		retcode = nv_alloc_rx(dev);
-	} else {
-		spin_lock_irqsave(&np->lock, flags);
-		tx_work = nv_tx_done_optimized(dev, np->tx_ring_size);
-		spin_unlock_irqrestore(&np->lock, flags);
+			rx_count = nv_rx_process(dev, budget);
+			retcode = nv_alloc_rx(dev);
+		} else {
+			spin_lock_irqsave(&np->lock, flags);
+			tx_work += nv_tx_done_optimized(dev, np->tx_ring_size);
+			spin_unlock_irqrestore(&np->lock, flags);
 
-		rx_work = nv_rx_process_optimized(dev, budget);
-		retcode = nv_alloc_rx_optimized(dev);
-	}
+			rx_count = nv_rx_process_optimized(dev, budget);
+			retcode = nv_alloc_rx_optimized(dev);
+		}
+	} while (retcode == 0 &&
+		 rx_count > 0 && (rx_work += rx_count) < budget);
 
 	if (retcode) {
 		spin_lock_irqsave(&np->lock, flags);

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