[PATCH 6/13] forcedeth: add/modify tx done with limit

[PATCH 6/13] forcedeth: add/modify tx done with limit

[Ayaz Abdulla]

[-- Attachment #1: Type: text/plain, Size: 290 bytes --]

There are two tx_done routines to handle tx completion processing. Both 
these functions now take in a limit value and return the amount of tx 
completions. This will be used by a future patch to determine the total 
amount of work done.

Signed-off-by: Ayaz Abdulla <aabdulla@nvidia.com>


[-- Attachment #2: patch-forcedeth-tx-done-limit --]
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--- old/drivers/net/forcedeth.c	2009-03-05 10:41:12.000000000 -0800
+++ new/drivers/net/forcedeth.c	2009-03-05 10:41:29.000000000 -0800
@@ -2397,14 +2397,16 @@
  *
  * Caller must own np->lock.
  */
-static void nv_tx_done(struct net_device *dev)
+static int nv_tx_done(struct net_device *dev, int limit)
 {
 	struct fe_priv *np = netdev_priv(dev);
 	u32 flags;
+	int tx_work = 0;
 	struct ring_desc* orig_get_tx = np->get_tx.orig;
 
 	while ((np->get_tx.orig != np->put_tx.orig) &&
-	       !((flags = le32_to_cpu(np->get_tx.orig->flaglen)) & NV_TX_VALID)) {
+	       !((flags = le32_to_cpu(np->get_tx.orig->flaglen)) & NV_TX_VALID) &&
+	       (tx_work < limit)) {
 
 		dprintk(KERN_DEBUG "%s: nv_tx_done: flags 0x%x.\n",
 					dev->name, flags);
@@ -2430,6 +2432,7 @@
 				}
 				dev_kfree_skb_any(np->get_tx_ctx->skb);
 				np->get_tx_ctx->skb = NULL;
+				tx_work++;
 			}
 		} else {
 			if (flags & NV_TX2_LASTPACKET) {
@@ -2447,6 +2450,7 @@
 				}
 				dev_kfree_skb_any(np->get_tx_ctx->skb);
 				np->get_tx_ctx->skb = NULL;
+				tx_work++;
 			}
 		}
 		if (unlikely(np->get_tx.orig++ == np->last_tx.orig))
@@ -2458,17 +2462,19 @@
 		np->tx_stop = 0;
 		netif_wake_queue(dev);
 	}
+	return tx_work;
 }
 
-static void nv_tx_done_optimized(struct net_device *dev, int limit)
+static int nv_tx_done_optimized(struct net_device *dev, int limit)
 {
 	struct fe_priv *np = netdev_priv(dev);
 	u32 flags;
+	int tx_work = 0;
 	struct ring_desc_ex* orig_get_tx = np->get_tx.ex;
 
 	while ((np->get_tx.ex != np->put_tx.ex) &&
 	       !((flags = le32_to_cpu(np->get_tx.ex->flaglen)) & NV_TX_VALID) &&
-	       (limit-- > 0)) {
+	       (tx_work < limit)) {
 
 		dprintk(KERN_DEBUG "%s: nv_tx_done_optimized: flags 0x%x.\n",
 					dev->name, flags);
@@ -2492,6 +2498,7 @@
 
 			dev_kfree_skb_any(np->get_tx_ctx->skb);
 			np->get_tx_ctx->skb = NULL;
+			tx_work++;
 
 			if (np->tx_limit) {
 				nv_tx_flip_ownership(dev);
@@ -2506,6 +2513,7 @@
 		np->tx_stop = 0;
 		netif_wake_queue(dev);
 	}
+	return tx_work;
 }
 
 /*
@@ -2578,7 +2586,7 @@
 
 	/* 2) check that the packets were not sent already: */
 	if (!nv_optimized(np))
-		nv_tx_done(dev);
+		nv_tx_done(dev, np->tx_ring_size);
 	else
 		nv_tx_done_optimized(dev, np->tx_ring_size);
 
@@ -3433,7 +3441,7 @@
 		nv_msi_workaround(np);
 
 		spin_lock(&np->lock);
-		nv_tx_done(dev);
+		nv_tx_done(dev, np->tx_ring_size);
 		spin_unlock(&np->lock);
 
 #ifdef CONFIG_FORCEDETH_NAPI

Re: [PATCH 6/13] forcedeth: add/modify tx done with limit

[David Miller]

From: Ayaz Abdulla <aabdulla@nvidia.com>
Date: Thu, 05 Mar 2009 13:02:10 -0500

> There are two tx_done routines to handle tx completion processing. Both these functions now take in a limit value and return the amount of tx completions. This will be used by a future patch to determine the total amount of work done.
> 
> Signed-off-by: Ayaz Abdulla <aabdulla@nvidia.com>

Applied.

But I would absolutely not count TX completion processing in the
NAPI work limit as you do in one of the subsequent patches.

TX completely is just buffer freeing, very cheap.

Whereas RX processing involves actually network stack processing
which is real work and is what NAPI should be limiting.

Also, please get rid of the NAPI config option for this driver and
make NAPI unconditionally enabled.

Thanks.

Re: [PATCH 6/13] forcedeth: add/modify tx done with limit

[Ayaz Abdulla]

David Miller wrote:
> From: Ayaz Abdulla <aabdulla@nvidia.com>
> Date: Thu, 05 Mar 2009 13:02:10 -0500
> 
> 
>>There are two tx_done routines to handle tx completion processing. Both these functions now take in a limit value and return the amount of tx completions. This will be used by a future patch to determine the total amount of work done.
>>
>>Signed-off-by: Ayaz Abdulla <aabdulla@nvidia.com>
> 
> 
> Applied.
> 
> But I would absolutely not count TX completion processing in the
> NAPI work limit as you do in one of the subsequent patches.
> 

I agree. However, I am counting tx work only for the purpose of 
interrupt moderation.  The tx work count is not included in the NAPI 
limit check.
ie.

+	nv_change_interrupt_mode(dev, tx_work + rx_work);

-	if (pkts < budget) {
+	if (rx_work < budget) {


> TX completely is just buffer freeing, very cheap.
> 
> Whereas RX processing involves actually network stack processing
> which is real work and is what NAPI should be limiting.
> 
> Also, please get rid of the NAPI config option for this driver and
> make NAPI unconditionally enabled.
> 

Sure, I will submit a new patch for removing the config option.

> Thanks.

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