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SubjectRe: Slow PPP?

On Tue, 26 Mar 1996, Michael Nelson wrote:

> I really don't think the "slow ppp" problems people are having have
> anything to do with the kernel or with ppp 2.2.0e, for that matter. I
> have been running ppp 2.2.0e ever since it came out, with every kernel
> that has been released since then.

It may be that in your particular case you are not experiencing the
probelms described. I certainly am, and I'm no newbie when it comes to
either Linux or Modems.

> I get consistently fast transfers on good sites. I have a USR Sportster
> 33.6K modem, I _always_ connect at 28.8 to my ppp server (Livingston
> Portmaster with Courier V.everything modem), and I see 3.1k transfer
> rates whenever connected to a fast site.

What sort of file are you getting 3.1k on ? I hope that's a .zip, .Z or
.gz file or I would say you do have a problem :-). What throughput do you
get if you ftp files generated as follows to/from your PPP server system?

dd if=/dev/zero of=./emptyfile bs=1k count=100
dd if=/dev/random of=./fullfile bs=1k count=100

I just tried an experiment to check the throughput (using ftp) between my
host and my ISP. Firstly in Windoze 3.1, and then in Linux (1.3.77). My
modem is a USR Sportster 28.8K internal ISA-bus, connecting to my ISP at
28.8k (serial port set spd_vhi, 115,200 baud, h/w handshake)

100Kb test file Winsock ppp-2.2.0e
/pub/test/emptyfile (compressible) 6.24 Kb/s 3.80 Kb/s (-40%)
/pub/test/fullfile (non-compressible) 3.11 Kb/s 2.80 Kb/s (-10%)

I use the same box booted into Dos or Linux, so there are no hardware
changes, and the transfers were done <10 minutes apart to avoid changes at
the ISP's end where possible.

> There's gotta be something else wrong in your setups, guys... nothing
> wrong with the kernels or ppp 2.2.0e as far as I can tell.

Perhaps there is, but WHAT ?????? I've checked the link quality and
everything looks perfect. It just seems to be going SLOW... Packets come
in, packets go out, LCP stuff is exchanged every few seconds, there are NO
errors reported by netstat, pppd-debug or kernel debug.

> Sorry, because I know this isn't particularly helpful in terms of
> solving your problem, but IMHO if you are looking at the kernel code or
> the ppp code for the answer, you're looking in the wrong place.

I sort-of agree. pppd hasn't changed since everything was OK. I checked
the kernel ppp driver changes, and came up with a list of changes...
almost nothing, and none of it seemed important. I can't see anything
major in the serial port driver either :-( I guess it's somewhere else in
the kernel tho' - interrupts or scheduling have been suggested.

Ho hum.

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