cvs commit: src/sys/dev/em if_em.c

Eric Anderson anderson at
Tue Aug 22 18:58:57 UTC 2006

On 08/22/06 13:53, Gleb Smirnoff wrote:
> On Tue, Aug 22, 2006 at 10:35:19AM -0500, Eric Anderson wrote:
> E> >E> >P> yongari     2006-08-22 02:32:48 UTC
> E> >E> >P> 
> E> >E> >P>   FreeBSD src repository
> E> >E> >P> 
> E> >E> >P>   Modified files:
> E> >E> >P>     sys/dev/em           if_em.c 
> E> >E> >P>   Log:
> E> >E> >P>   It seems that em(4) misses Tx completion interrupts under certain
> E> >E> >P>   conditions. The cause of missing Tx completion interrupts comes 
> E> >from
> E> >E> >P>   Tx interrupt moderation mechanism(delayed interrupts) or chipset 
> E> >bug.
> E> >E> >P>   If Tx interrupt moderation mechanism is the cause of false 
> E> >watchdog
> E> >E> >P>   timeout error we should have to fix all device drivers that have 
> E> >Tx
> E> >E> >P>   interrupt moderation capability. We may need more investigation
> E> >E> >P>   for this issue. Anyway, the fix is the same for both cases.
> E> >E> >P>   
> E> >E> >P>   This should fix occasional watchdog timeout errors seen on a few
> E> >E> >P>   systems.
> E> >E> >P>   
> E> >E> >P>   Reported by:    -net, Patrick M. Hausen < hausen AT punkt DOT de >
> E> >E> >P>   Tested by:      Patrick M. Hausen < hausen AT punkt DOT de >
> E> >E> >
> E> >E> >This look like a workaround, not a fix the root of the problem. Several
> E> >E> >people on net said that this problem disappears if debug.mpsafenet=0.
> E> >E> >So I think there is a problem in FreeBSD or driver, not in chip.
> E> >E> 
> E> >E> And it also worked perfectly for a very very long time until 6.x tree. 
> E> >E> I went from 5-STABLE to 6-STABLE and started seeing it a lot ( a few 
> E> >E> times per day) on a couple servers.
> E> >
> E> >In 5-STABLE the watchdog events were not logged, but the watchdog was
> E> >processed.
> E> 
> E> But my interface never seemed to disappear (I page if the interface goes 
> E> down), and I'd still notice a link up/down, correct?
> In 5-STABLE the interface up/down events were not logged, either.

Ok.  Well, I just recalled that on a separate system (my workstation 
actually), I went from 6.1-R to 6-STABLE as of about 8 days ago, and it 
now exhibits the problem too, which hasn't happened before.


Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.

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