[Bridge] Getting statistics from a bridge

[Bridge] Getting statistics from a bridge

[Leigh Sharpe]

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Hi All,
 Is there any way of getting detailed statistics from a bridge?
Specifically, I need to know how many frames may have been dropped
because they exceed the MTU of the underlying port. I'm having a few
issues with MTUs not agreeing.
 
Regards,
             Leigh
 
Leigh Sharpe
Network Systems Engineer
Pacific Wireless
Ph +61 3 9584 8966
Mob 0408 009 502
Helpdesk 1300 300 616
email lsharpe@pacificwireless.com.au
<blocked::mailto:lsharpe@pacificwireless.com.au> 
web www.pacificwireless.com.au
<blocked::http://www.pacificwireless.com.au/> 
 

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Re: [Bridge] Getting statistics from a bridge

[Stephen Hemminger]

On Wed, 23 Apr 2008 10:53:12 +1000
"Leigh Sharpe" <lsharpe@pacificwireless.com.au> wrote:

> Hi All,
>  Is there any way of getting detailed statistics from a bridge?
> Specifically, I need to know how many frames may have been dropped
> because they exceed the MTU of the underlying port. I'm having a few
> issues with MTUs not agreeing.
>  
> Regards,
>              Leigh
>  

It would not be hard to modify kernel to use one of the existing statistics on
the bridge interface to keep track of the dropped packets. I'll look into it
if no one else gets to it first (hint, hint)

Re: [Bridge] Getting statistics from a bridge

[Jaime Medrano]

On Wed, Apr 23, 2008 at 10:43:40AM -0700, Stephen Hemminger wrote:
> On Wed, 23 Apr 2008 10:53:12 +1000
> "Leigh Sharpe" <lsharpe@pacificwireless.com.au> wrote:
> 
> >  Is there any way of getting detailed statistics from a bridge?
> > Specifically, I need to know how many frames may have been dropped
> > because they exceed the MTU of the underlying port. I'm having a few
> > issues with MTUs not agreeing.
> 
> It would not be hard to modify kernel to use one of the existing statistics on
> the bridge interface to keep track of the dropped packets. I'll look into it
> if no one else gets to it first (hint, hint)
> 

I think this change will do it.

Regards,
Jaime Medrano.

--- linux-2.6.25.orig/net/bridge/br_forward.c	2008-04-24 11:04:32.000000000 +0200
+++ linux-2.6.25/net/bridge/br_forward.c	2008-04-24 15:15:02.000000000 +0200
@@ -35,9 +35,10 @@
 int br_dev_queue_push_xmit(struct sk_buff *skb)
 {
 	/* drop mtu oversized packets except gso */
-	if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
+	if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb)) {
+		rcu_dereference(skb->dev->br_port)->br->statistics.tx_dropped++;
 		kfree_skb(skb);
-	else {
+	} else {
 		/* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
 		if (nf_bridge_maybe_copy_header(skb))
 			kfree_skb(skb);

Re: [Bridge] Getting statistics from a bridge

[Stephen Hemminger]

On Thu, 24 Apr 2008 15:41:29 +0200
Jaime Medrano <jaime.medrano@gmail.com> wrote:

> On Wed, Apr 23, 2008 at 10:43:40AM -0700, Stephen Hemminger wrote:
> > On Wed, 23 Apr 2008 10:53:12 +1000
> > "Leigh Sharpe" <lsharpe@pacificwireless.com.au> wrote:
> > 
> > >  Is there any way of getting detailed statistics from a bridge?
> > > Specifically, I need to know how many frames may have been dropped
> > > because they exceed the MTU of the underlying port. I'm having a few
> > > issues with MTUs not agreeing.
> > 
> > It would not be hard to modify kernel to use one of the existing statistics on
> > the bridge interface to keep track of the dropped packets. I'll look into it
> > if no one else gets to it first (hint, hint)
> > 
> 
> I think this change will do it.
> 
> Regards,
> Jaime Medrano.

There is still the possiblity of RCU race during removal. I'll fix it up.
I am adding better statistics as part of other patch.