Re: nve(4) patch - please test!

From: David G. Lawrence <dg_at_dglawrence.com>
Date: Wed, 4 Jan 2006 16:21:03 -0800
> Since I sent the mail below I had to discover that the new driver
> has a problem when no cable is plugged in, at least on my Asus board.
> 
> It doesn't only run into timeouts, during some of these timeout the
> machine or at least the keyboard hangs for about a minute.
> 
> Is there anything I can do to help debug this?

   I ran into this problem recently as well and spent some time diagnosing
it. It's not that the cable isn't plugged in - rather it happens whenever
the traffic levels are low.
   The problem is that the nvidia-supplied portion of the driver is defering
the releasing of the completed transmit buffers and this occasionally
results in if_timer expiring, causing the driver watchdog routine to be
called ("device timeout"). The watchdog routine resets the card and the
nvidia-supplied code sits in a high-priority loop waiting for the card
to reset. This can take many seconds and your system will be hung until
it completes.
   I have a work-around patch for the problem that I've attached to this
email. It simply disables the watchdog. A real fix would involve accounting
for the outstanding transmit buffers differently (or perhaps not at all -
e.g. always attempt to call the nvidia-supplied code and if a queue-full
error occurs, then wait for an interrupt before trying to queue more
transmit packets).

-DG

David G. Lawrence
President
Download Technologies, Inc. - http://www.downloadtech.com - (866) 399 8500
The FreeBSD Project - http://www.freebsd.org
Pave the road of life with opportunities.

Received on Wed Jan 04 2006 - 23:21:16 UTC

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