Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 5 May 2003 17:32:49 +0200 | From | Stephan von Krawczynski <> | Subject | Re: ISDN massive packet drops while DVD burn/verify |
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On Mon, 5 May 2003 16:23:00 +0200 Karsten Keil <kkeil@suse.de> wrote:
> Hi Stephan,
Hi Karsten,
long time no hear ;-)
> > Sorry Alan, "been there, done that" > > I made ISDN work on just about anything that you would call an OS on > > sometimes quite ancient hardware (compared to nowadays), and I really > > cannot imagine that the combined (though sometimes confusing) efforts of > > you, Andre, Pavel, name-one on IDE made a dual 1.4 GHz PIII slower > > (responding) than a M68k 7,14 MHz with a polling IDE interface - which > > happens to be the slowest thing I ever did ISDN programming on > > _flawlessly_. > > > > No Alan and Kai are right. > > The problem with the Infineon ISDN chips is that the fifos are small and so > IRQ latency is relativ critical. 32 or 64 bytes are only 4/8 ms, and if one > of these 32 Byte is dropped, the complete frame is lost. Modern ethernet > cards allways have fifos for multiple complete frames, so that such things > don't happen here.
I know the relatively small fifos. On the other hand compared to the ridiculous throughput of 8 kByte/sec (single channel) (which most people seem to ignore in this discussion), it is ok.
Let me simply ask back: is the IDE code in nowadays 2.4 kernel so bad, that a dual 1,4 GHz PIII cpu with 3 GB ram performs much worse than a 90 MHz P I with 64 MB and OS/2 on it??? _My_ isdn drivers showed _no_ such problems under OS/2 and IDE load...
How did we manage to become that bad?
> You can try to use HFC based ISDN cards (e.g. Conrad: ISDN TA 128K) the > fifos are much bigger (7.5kB) so at least 4 complete 1500 byte frames can be > handled without segmentation. That increase the IRQ latency a lot (~900 ms).
I know HFC is nice. But that cannot mean ISAC/HSCX must have dropouts. You have to have long interrupt lock outs for such a behaviour, which cannot be intended at all.
-- Regards, Stephan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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