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SubjectRe: 3c59x problem
Alan Cox wrote:

> > the card works perfectly fine, but the linux ppp driver leaves a lot to
> > desire. Lowsy transfer rates, all in all it's terrible.
>
> You should be getting serial line speed transfers with ppp. If not then
> man hdparm and read about hdparm -u. If that doesnt help drop me a note

I didn't see any reply about a successful resolution, but I concur on the
problem. I've got tcpdump output on both ends of the ppp connection, and raw
serial dumps (from pppd option "kdebug 7") that corroborate that it is not due
to dropped/lost serial bytes (hence not due to problems with interrupt
latency, hdparm -u), not due to asyncmap being improperly set, not due to
mru/mtu, not due to differences in DCE versus DTE speed. In short, linux is
simply omitting certain packets, which after some time are finally resent.
Yet, if the two linux boxen are connected by ethernet rather than ppp/serial,
the tcpdumps look perfectly normal.

Alan - do you have any suggestions for how to track this down further? It's
very annoying to be getting 1+ second pauses every 10+ seconds of interactive
activity.

Kris

P.S. pppd-2.3.5 on both ends, 220F on both ends (UP, hdparm -u 1 on one; SMP
scsi/raid0 on other), slackware-3.6 based.


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