Re: bad PPP Performance (with and without IRQTUNE)

Edward Welbon (
Wed, 4 Sep 1996 18:14:47 -0500 (CDT)

On Wed, 4 Sep 1996, Michael Neuffer wrote:

> Symptoms: system is normally lightning FAST. Compiles a complete kernel, on
> an Iomega Jaz drive in about 3-4 minutes (distclean, depend, make, zlilo,
> modules, modules_install).

Very good, I'd like to know more of the details of the configuration.

> PPP is on either Motorola BitSRFR PRO (115,200 on one B channel) or a new USR
> Sportster ``33.6 capable'', again, at 115,200.
> setserial /dev/cua{1,2} spd_vhi is done on both.
> Using CU, either on the built-in UARTs or the external one, serial I/O is FAST.
> Hard to measure but flies on the screen, with the ISDN linke visibly faster.
> Running PPP (pppd 2.2.0f) disconnects two/three times upon dialup from
> either line. Once connection is established, performance is horrendous.
> Typically ftp will do 800 bytes/sec on the ISDN line. Less on the
> modem.

Um, 800 bytes/second is a mite slow.

Is this MLPPP on two channels or is this one channel. I find that
non-PAP and non-CHAP connections are abysmal. On my BSPro (with 1H
firware) I get about 10KB/s with 115200, with 230400 baud, I get about
13.7Kb/s. This is the effective rate, I don't know what the bit rate
is (encapsulation and all that ya know).

I am running 2.2.0e and 2.2.0f (on the other system), the system that I
usually measure ISDN performance on is a 133Mhz 486. It has kernel
1.3.97, the kernel one the other system 1.99.9

It should work. I would be surprised to see that the P6 is the problem,
but I would also be surprised that the P6 is going to help get you over
13.7KB/s. There is encapsulation overhead everywhere. It will cost in
terms of bit bandwidth and processing time.

Ed Welbon;;