netdev - Re: r8169: slow samba performance

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Date:	Sun, 9 Sep 2007 17:33:12 +0200
From:	Francois Romieu <romieu@...zoreil.com>
To:	David Madsen <david.madsen@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: r8169: slow samba performance

David Madsen <david.madsen@...il.com> :
> >Does "acceptable" mean that there is a noticeable difference when compared
> >to the patch based on a busy-waiting loop ?
> 
> I noticed a somewhat significant difference between patch #0002 and a
> busy wait loop with ndelay(10). Write performance was equivalent in
> both cases as should be the case.  Read perfomance for me maxed out

Do you have some (gross) figure for the write performance ?

> around 150ish megabit whereas switching to the ndelay(10) loop brought
> up average performance around 350ish megabit while reading the same
> files over samba.

Hardly extatic. :o/

Do you see a difference in the system load too, say a few lines of 'vmstat 1' ?

Can you add the patch below on top of #0002 and see if there is some
benefit from it ?

diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
index b85ab4a..8d8fff3 100644
--- a/drivers/net/r8169.c
+++ b/drivers/net/r8169.c
@@ -2457,6 +2457,7 @@ static int rtl8169_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	smp_wmb();
 
 	RTL_W8(TxPoll, NPQ);	/* set polling bit */
+	RTL_R8(TxPoll);
 
 	if (TX_BUFFS_AVAIL(tp) < MAX_SKB_FRAGS) {
 		netif_stop_queue(dev);


I'd welcome if you could try the patch below on top of #0002 too:

diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
index b85ab4a..840df3b 100644
--- a/drivers/net/r8169.c
+++ b/drivers/net/r8169.c
@@ -2457,6 +2457,17 @@ static int rtl8169_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	smp_wmb();
 
 	RTL_W8(TxPoll, NPQ);	/* set polling bit */
+{
+	static unsigned int wait_max = 0;
+	unsigned i;
+
+	for (i = 0; (RTL_R8(TxPoll) & NPQ) && (i < 1000); i++)
+		ndelay(10);
+	if (i > wait_max) {
+		wait_max = i;
+		printk(KERN_INFO "%s: wait_max = %d\n", dev->name, wait_max);
+	}
+}
 
 	if (TX_BUFFS_AVAIL(tp) < MAX_SKB_FRAGS) {
 		netif_stop_queue(dev);

-- 
Ueimor
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