Re: Very poor PPP interface performance
Re: Very poor PPP interface performance
- Subject: Re: Very poor PPP interface performance
- From: Dave MacLachlan <email@hidden>
- Date: Tue, 02 Nov 2004 18:42:16 -0800
Have you tried looking at it with Shark to see if you can figure out
where the bottleneck is?
Cheers,
Dave
On Oct 26, 2004, at 13:52, Jean-Edouard BABIN wrote:
Hello
You're right, i also already setup a ppp tunnel over ssh
With something like
pppd pty 'ssh -x -t -e none user@server /usr/sbin/pppd passive noauth
9600'
noauth 10.0.0.1:10.0.0.2
and get the same poor performance, and bad ping also :/
on 26/10/04 20:55, « Jamie Wood » <email@hidden> wrote:
I have noticed that the performance of the PPP interface in Mac OS X
10.3.5
is not very good at all. I have written a simple program that brings
up a
PPP interface, configures it using "ifconfig", and reads incoming
packets.
If I use another program to repeatedly send UDP packets to my
newly-created
PPP interface in a tight loop, the sendto() function quickly begins to
return a "No buffer space available" error. The program which is
reading
packets from the PPP interface only reports that about 1% of the
packets
even get through.
If I run a similar set of tests on Linux, none of the UDP packets are
dropped, and sendto returns no errors.
In another test, I tried using iperf to measure the throughput of a
ssh-pppd
tunnel. The most I can get without compression enabled is 1.2
Mbits/sec over
a 10 Mbit link. The same test on Linux results in numbers which are
close to
link speed (one of our tests resulted in ~28 Mbits/sec).
One interesting thing I and my collegues have observed is that if a
Linux
box is used for one end of the ssh-pppd tunnel, we get about 7
Mbits/sec
download speed (Linux->Mac OS X) but only about 800 Kbits/sec upload
speed
(Mac OS X->Linux).
All of this seems to indicate that there is some sort of performance
problem
between the TCP stack and the PPP interface code, which is causing
some sort
of serious delay when the interface picks up events from the stack.
Any information about this behavior, and suggestions for possible
workarounds/fixes would be greatly appreciated.
Thanks,
Jamie Wood
--
Jean-Edouard BABIN
Mail: email@hidden
Web : www.Jeb.com.fr
IRC : Jeb @ Undernet
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