Subject: Re: [PATCH -rt DO NOT APPLY] Fix for tg3 networking lockup
From: Daniel Walker <dwalker@mvista.com>
Reply-To: dwalker@mvista.com
To: David Miller <davem@davemloft.net>
Cc: tytso@mit.edu, mchan@broadcom.com, herbert@gondor.apana.org.au,
       linux-kernel@vger.kernel.org, netdev@vger.kernel.org
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Date: Thu, 03 Aug 2006 17:03:05 -0700
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On Thu, 2006-08-03 at 16:56 -0700, David Miller wrote:
> From: Theodore Tso <tytso@mit.edu>
> Date: Thu, 3 Aug 2006 19:53:26 -0400
> 
> > Any suggestions on how I could figure out what was really going on and
> > what would be a better fix would be greatly appreciated.
> 
> As Michael explained, it's the ASF heartbeat sent by tg3_timer() that
> must be delivered to the chip within certain timing constraints.
> 
> If you had any watchdog devices on this machine, they would likely
> trigger too and reset your machine :)

That's not broken behavior in RT .. That's just plain old task
priorities. Some high priority task (SCHED_FIFO prio 99) is sucking up a
lot of the CPU. But that's 100% legal in SCHED_FIFO.

Daniel

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