Re: NET_SCHED cbq dropping too many packets on a bonding interface

[Patrick McHardy]

Jarek Poplawski wrote:
> On Thu, May 15, 2008 at 06:09:36PM +0200, Patrick McHardy wrote:
> > Kingsley Foreman wrote:
> > > i just rolled back the kernel to 2.6.24 and im seeing the same thing,
> > >
> > > I was using 2.6.22 before and didn't see the problem, txqueuelen on the 
> > > bond0 interface is 0 (the default)
> > That might explain things, although it shouldn't have worked before
> > either.
> >
> > CBQ creates default pfifo qdiscs for its leaves, these use a limit
> > of txqueuelen or 1 if it is zero. So even small bursts will cause
> > drops. Do things improve if you set txqueuelen to a larger value
> > *before* configuring the qdiscs?
>
> Kingsley wrote to me that even after changing txqueuelen to 1000 the
> "dropped" number didn't change much. A debugging patch with printks
> around all "sch->qstats.dropps++" showed only the end of cbq_enqueue().


Thats where packets dropped by default pfifo would be accounted.
Did you change txqueuelen before or after setting up the qdiscs?

> I've asked to check tomorrow "pfifo limit 1000" for these drops too.

That will clear it up.

> > Another thing is that CBQ on bond will probably not work properly
> > at all, it needs a real device since it measures the timing between
> > dequeue events for idle time estimation. On software devices this
> > doesn't work.
>
> Right, but these drops without any sign of overactions or overlimits
> seem to show it's not about shaping (or it's not counted/documented
> enough).

Yes, these drops are probably unrelated, just thought I mention it.
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