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Date: Thu, 3 Aug 2006 20:07:07 -0400
From: Theodore Tso <tytso@mit.edu>
To: David Miller <davem@davemloft.net>
Cc: mchan@broadcom.com, herbert@gondor.apana.org.au,
       linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH -rt DO NOT APPLY] Fix for tg3 networking lockup
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On Thu, Aug 03, 2006 at 04:43:11PM -0700, David Miller wrote:
> From: "Michael Chan" <mchan@broadcom.com>
> Date: Thu, 03 Aug 2006 16:28:19 -0700
> 
> > > eth0: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[1] Split[0] WireSpeed[0] TSOcap[0]
> > 
> > We'll see if we can do away with the timer-based heartbeat.  That's
> > probably the best solution.
> 
> The tg3 driver is not the only device in the world that requires a
> timer based "ping" to work.  The watchdog drivers and the softlockup
> detector are other instances which require a timer to not be delayed
> an unreasonable amount of time.
> 
> Therefore TG3 is not unique in this regard, and I thus don't think
> it's worthwhile to change tg3 just to accomodate this broken behavior
> of the RT patches.

Removing the timer-based "ping" might be a good thing to do from the
point of view of reducing power utilization of laptops (but hey, I
don't have a tg3 in my laptop, so I won't worry about it a whole lot :-), 
but I agree that in general the RT patches need to be able to
call functions such as tg3_timer() reliably even when under a high
real-time process workload, without needing to use the blunt hammer of
"chrt -f 95 `pidof softirq-timer`".  (Since not all timer callbacks
need to be run at rt prio 95.)

						- Ted
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