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SubjectRe: 2.0.30 serial.c, ppp.c and pppd-2.2 questions
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Theodore Y. Ts'o wrote:

> Rob, what else do you have on your system? Although I haven't done the
> test in a while, the serial driver was originally written to be able to
> support 115kbaud on a 386/40. (Granted this was a kermit transfers, not
> PPP; but it was a looped back 115kbaud transfer where the transmitting
> and receiving ports were on the same CPU, doubling the work.)

This is a bad test. Why? Because if the recieving end stops working for
a tenth of a second, the transmitting end will too. No overruns/anything.

My Specialix card also loops back just fine at 115k. It just doesn't
talk to a modem at 115k. This time it's probably a baud-rate
incompatibility: The specialix card can only do 111k6 due to "clock
divider" issues.

> The fact that your 486/66 isn't keeping up makes me wonder what other
> sources of interrupts you are having on your system.

I too have a 486/66, this time the serial ports are on a specialix
card, not the standard serial ports. The flip buffers overflow when I
get the machine paging heavily. It'll be doing a few hundred IDE
interrupts per second around that time.....

The specialix has an 8byte FIFO, interrupt theshold is set at 6. I
seem to have overrun reporting on this thing turned off. But wouldn't
ppp report bad packets if that happened?

% cat /proc/net/dev
Inter-| Receive | Transmit
face |packets errs drop fifo frame|packets errs drop fifo colls carrier
ppp0: 1488 0 0 0 0 1387 0 0 0 0 0

Alas, the counters probably get reset on every session, and I didn't
get any flip buffer overrun last session.

Roger.

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