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SubjectRe: [PATCH RFC] netpoll: don't spin forever sending to stopped queues
Matt Mackall wrote:
> On Thu, Jun 08, 2006 at 07:15:50PM -0700, Jeremy Fitzhardinge wrote:
>> Here's a patch. I haven't tested it beyond compiling it, and I don't
>> know if it is actually correct. In this case, it seems pointless to
>> spin waiting for an even which will never happen. Should
>> netif_poll_disable() cause netpoll_send_skb() (or something) to not even
>> bother trying to send? netif_poll_disable seems mysteriously simple to me.
>> J
> Did this work for you at all?

No, it didn't appear to help; I get the same symptom. I think fix is
correct (in that its better than what was there before), but there's
probably more going on in my case. I haven't looked into it more deeply
yet. I suspect there's another netpoll code path which is spinning
forever on an XOFFed queue.

>> When transmitting a skb in netpoll_send_skb(), only retry a limited
>> number of times if the device queue is stopped.
> Where limited = once?

No, it reuses the existing retry logic. It retries 20000 times with a
50us pause between attempts, so up to a second. This seems excessive to
me; I don't know where those original numbers came from. I tried 5000
retries, but it didn't make any difference to my case.

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