Re: [PATCH RFC] netpoll: don't spin forever sending to stopped queues

[Matt Mackall <mpm@selenic.com>]

On Mon, Jun 12, 2006 at 01:57:58PM -0700, Jeremy Fitzhardinge wrote:
> 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.

Ahh, right. I forgot that I'd done that. Can you resend?

-- 
Mathematics is the supreme nostalgia of our time.