Re: ISDN massive packet drops while DVD burn/verify

Stephan von Krawczynski
2003-04-19T17:40:11Z

On Fri, 18 Apr 2003 09:25:21 -0500 (CDT)
Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de> wrote:

> On Wed, 16 Apr 2003, Stephan von Krawczynski wrote:
>
> > I just experienced a massive ISDN problem while writing DVDs.
> > It looks like bigger IP packets (bigger than normal ICMP ping)
> > get simply dropped most of the time.
> > I think the packets get lost because some allocation continously fails and
> > disk i/o is faster in re-gaining the mem, but I am not quite sure. Could as
> > well be ide-scsi is partially busy-looping the box to death.
> > As soon as DVD writing is stopped everything comes back to normal.
> > Reading DVDs does not show the problem btw.
> > ping -s 1500 a.b.c.d shows about 5 packets, then stops.
>
> My best guess would be that IDE blocks IRQs for too long and hisax
> interrupts get lost. You could try whether hdparm -u1 helps, and a
> debugging log from the hisax driver may confirm over/underruns.

I don't buy that explanation. Reason is simple: during this all network
connections work flawlessly, and they do have quite a lot of interrupts
compared to ISDN. ISDN is so slow and has so few interrupts that it is quite
unlikely in a SMP-beyond-GHz-limit box that you loose some. The ancient
hardware days are long gone ...

> --Kai

Regards
Stephan