Re: 2.6.27.19 + 28.7: network timeouts for r8169 and 8139too

[David Dillow <dave@thedillows.org>]

On Thu, 2009-05-14 at 20:37 +0200, Michael Riepe wrote:
> 
> David Dillow wrote:
> > On Tue, 2009-05-12 at 22:29 +0200, Michael Riepe wrote:
> > The patched driver runs on 2.6.27 and survives my 5 minutes 'dd
> > if=/dev/zero bs=1024k | nc target 9000' test which usually dies in less
> > than 90 seconds on 2.6.28+.
> 
> Not on my system:

> This happened less than half a minute after the transfer had started.
> And it's going to happen earlier if I increase the load. With four
> connections to two other hosts, the transmission usually pauses after
> less than ten seconds. Sometimes it lasts for only two or three seconds.

Bummer, but a good data point; thanks for testing.

I added some code to print the irq status when it hangs, and it shows
0x0085, which is RxOK | TxOK | TxDescUnavail, which makes me think we've
lost an MSI-edge interrupt somehow. You being able to reproduce it on
2.6.27 where I cannot leads me to think that the bisection down into the
genirq tree just changed the timing and made it easier to hit after it
was merged.

So, I suppose a good review of the IRQ handling of r8169.c is in order,
though my SATA disks (AHCI w/ MSI irqs) also seem to have similar issues
with delays, though that is entirely unqualified and unmeasured.

Dave