netdev - Re: bonding with 3c59x driver

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Date:	Tue, 14 Feb 2012 20:27:12 +0100
From:	Jean Delvare <jdelvare@...e.de>
To:	Rick Jones <rick.jones2@...com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Steffen Klassert <klassert@...hematik.tu-chemnitz.de>,
	Jay Vosburgh <fubar@...ibm.com>, netdev@...r.kernel.org
Subject: Re: bonding with 3c59x driver

On Tuesday 14 February 2012 07:27:05 pm Rick Jones wrote:
> On 02/14/2012 03:13 AM, Eric Dumazet wrote:
> > Le mardi 14 février 2012 à 12:06 +0100, Steffen Klassert a écrit :
> >> On Tue, Feb 14, 2012 at 11:22:10AM +0100, Jean Delvare wrote:
> >>> Well I am still curious why the 3c59x driver has such slow
> >>> polling when other drivers I have been testing are able to report
> >>> almost instantly when I remove a network cable. Could it be that
> >>> other network chips generate an interrupt on cable removal and
> >>> the 3com chips do not?
> >>
> >> Yes, at least some of the supported chips do not generate an
> >> interrupt on cable removal, so we have to check for this with a
> >> timer. --
> >
> > We could have a 5 sec timer in case device is a slave.
> >
> > diff --git a/drivers/net/ethernet/3com/3c59x.c
> > b/drivers/net/ethernet/3com/3c59x.c index 1282f04..e463d10 100644
> > --- a/drivers/net/ethernet/3com/3c59x.c
> > +++ b/drivers/net/ethernet/3com/3c59x.c
> > @@ -1841,7 +1841,7 @@ vortex_timer(unsigned long data)
> >   		ok = 1;
> >   	}
> >
> > -	if (!netif_carrier_ok(dev))
> > +	if (dev->flags&  IFF_SLAVE || !netif_carrier_ok(dev))
> >   		next_tick = 5*HZ;
> >
> >   	if (vp->medialock)
> 
> Does the device being a slave in a bond change the overheads of the
> check being performed?

No, but it changes the interest in having faster polling. The overhead 
is the same but the interest/overhead trade-off is much higher.

Without the patch above, doing bonding on top of 3c59x is simply not 
possible, at least not in active-backup mode. For other modes it depends 
if you are only interested in load balancing or also on redundancy.

-- 
Jean Delvare
Suse L3
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