S-x86; A strange way to achieve good PPP speed

evan cheng (evan@servtech.com)
Sat, 1 Jun 1996 06:55:29 -0400 (EDT)

Well, this one is bizzare.

As many Solaris 2.5 users have discovered, it's tough to achieve
good speed with ppp (or dp, as in my case) due to the flaky asy
driver. I have been experimenting a bit and caem up a way to
achieve good speed although I have not the faintest the idea why
it works.

First, in /etc/rc2.d/S69inet I added these two lines:

ndd -set /dev/tcp tcp_rexmit_interval_initial 5000
ndd -set /dev/tcp tcp_rexmit_interval_min 4000

This is to get around the re-transmit problem.

Second, in /etc/ttydefs, I added the following entries for baud rate
38400 and 115200.

X38400:38400 hupcl crtscts:38400 hupcl crtscts::X38400
X115200:115200 hupcl crtscts:115200 hupcl crtscts::X115200

I tried using X38400 for cua/b, it turned out okay. Transmitting
a jpg file from ISP to my machine gets me a throughput of 2.4 - 2.5k
per second. Okay, but not as fast I would like it to be. X115200 was
not as good, it gets me 2.3+k.

Then I discovered that if I boot up Solaris 2.5 with ttylabel X38400
for cua/b, but then changed it to X115200 before I start ppp (I use
admintool to do it as I am too lazy to find out how to set up a script
file to do it. Help?) I will get 2.7 - 2.8k throughput everytime. No
kidding. I thought it was just coincidence at first, but it was not.
It works everytime for me.

I have not the faintest idea why though. This works on my Pentium
100. I am not sure if it will work for anyone else. Please try and
let me know.

Cheers,

Evan

BTW, I am using dp-4.0, but I disabled S99dpconfig. I use two scripts
to start and stop ppp on demand. Not that it matters.
------------------------------------------------------------------
Evan Cheng evan@top.cis.syr.edu
Dept. CIS - Syracuse University http://www.cat.syr.edu/~evan
CASE Research Center (315) 423-7063

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