Problems with em interfaces on FreeBSD 6.1

[Landon Fuller]

On Aug 11, 2006, at 09:22, Jack Vogel wrote:

> On 8/11/06, Gleb Smirnoff <glebius at freebsd.org> wrote:
>>   Daniel,
>>
>> On Fri, Aug 11, 2006 at 01:42:32PM +0200, Daniel Ryslink wrote:
>> D> We have started to use the em driver only recently, after the  
>> upgrade to
>> D> gigabit connectivity (100 MBit NICs from Intel used the fxp  
>> driver).
>> D>
>> D> As for the frequency of the incidents, here is a grep of the  
>> messages:
>> D>
>> D> ~~~~~~~~~~~~ <slash> ~~~~~~~~~~~~~~
>> D> Aug  4 22:35:23 b2 kernel: em0: watchdog timeout -- resetting
>> D> Aug  5 00:09:20 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug  5 06:08:59 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug  6 12:38:16 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug  6 20:39:47 b2 kernel: em0: watchdog timeout -- resetting
>> D> Aug  7 18:37:29 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug  8 07:27:48 b2 kernel: em0: watchdog timeout -- resetting
>> D> Aug  8 09:38:17 b2 kernel: em0: watchdog timeout -- resetting
>> D> Aug  8 12:54:54 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug  8 22:41:17 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug  9 05:17:24 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug  9 10:56:10 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug  9 20:10:06 b2 kernel: em1: watchdog timeout -- resetting
>> D> Aug 11 08:41:44 b2 kernel: em0: watchdog timeout -- resetting
>> D> Aug 11 10:35:43 b2 kernel: em0: watchdog timeout -- resetting
>> D> ~~~~~~~~~~~~ <slash> ~~~~~~~~~~~~~~
>> D>
>> D> The driver used is version 3.2.18 (I wanted to use the Intel  
>> 6.1.4 as a
>> D> module, but I have found out that I made a mistake and  
>> accidentally loaded
>> D> the old 3.2.18 driver).
>> D>
>> D> I have dilemma now - which new driver to try? The 6.0.5  
>> submitted to the
>> D> current FreeBSD 6.1 branch (modified by you, I believe, on 8th  
>> August), or
>> D> the newest driver from Intel 6.1.4? Do you think one of these  
>> drivers
>> D> could solve my problems?
>>
>> I'm not sure whether new driver will solve your problems. You  
>> should give
>> a try to 6.1-STABLE which has 6.0.5 in it. The difference between  
>> 6.1.4 and
>> 6.0.5 is quite small, I doubt that 6.1.4 worth a try in your case.
>
> Gleb is right, the difference between my 6.0.5 and 6.1.4 driver are  
> minor
> and don't seem to have anything to do with your problem.
>
> I am happy Gleb got my code merged with tip of STABLE and would take
> that driver code if I were you, it will become 6.2 before long :)
>
> Watchdogs happen because of transmit cleanup failing, your instances
> are pretty widely seperated, it looks like some external network  
> problem
> perhaps?

We saw this issue here on SMP systems running 6.1; I've been meaning  
to set up a reproduction case in the lab and dig into the issue further.
Disabling the mpsafe network stack (debug.mpsafenet=0) is our  
temporary work-around; rwatson mentioned that this has the effect of  
forcing the interrupt handler for if_em to not run in parallel with  
the transmit code, which is likely what caused the problem to disappear.

-landonf
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