8-STABLE freezes on UDP traffic (DNS), 7.x doesn't
bra at fsn.hu
Mon Mar 29 19:21:47 UTC 2010
Pyun YongHyeon wrote:
> On Mon, Mar 29, 2010 at 12:57:59PM +0200, Attila Nagy wrote:
>> Michael Loftis wrote:
>>> --On Thursday, March 25, 2010 3:22 PM +0100 Attila Nagy <bra at fsn.hu>
>>>> Both unbound and python accepts DNS requests, and it seems when 25%
>>>> interrupt happens, only unbound is in *udp state, where it is 50%, both
>>>> programs are in that state.
>>> Try turning of hardware TSO/checksum offload if it's availble on your
>>> chipset? ifconfig <interface> -rxcsum -txcsum -tso -- I'm only using
>>> nfe chips right now, but w/ the TSO/CSUM on they lock up constantly
>>> under high load. We're pretty sure it's mostly the nfe driver, or the
>>> chips themselves, but have never ruled out some generic 8.x hardware
>>> offload issues.
>> Bingo, this solved the problem. The current uptime nears four days.
>> Previously I couldn't go further than a day.
>> The machine gets very light TCP load (and other machines which get work
>> well), so I guess it's UDP RX or TX checksum related.
> Hmm, this is unexpected result. Since you're using UDP, TSO is not
> involved in this issue. Because you disabled RX/TX checksum
> offloading could you check how many number of 'bad checksum' and
> and 'no checksum' you have from netstat(1)?
> To narrow down which side of checksum offloading causes the issue,
> would you just disable one side in a time? For instance, disable TX
> checksum offloading with RX checksum offloading enabled and see how
> bce(4) works.
> #ifconfig bce0 -txcsum rxcsum
> If that shows the same issue, try disabling RX checksum offloading
> but enabling TX checksum offloading.
> #ifconfig bce0 txcsum -rxcsum
It's interesting. During the day, I've disabled only HW checksumming and
left TSO enabled. It couldn't run more than a few hours.
I have disabled tso again to see what happens.
BTW, of course there is TCP traffic on that interface (DNS is also
available on TCP), maybe this causes the problem.
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