Linux-kernel mailing list archive 1998-10,: Re: pre-2.1.90..

# Re: pre-2.1.90..

David S. Miller (davem@dm.cobaltmicro.com)
Wed, 11 Mar 1998 00:22:33 -0800

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Date: Wed, 11 Mar 1998 07:07:29 +0000 (GMT)
From: Matthew Kirkwood <weejock@ferret.lmh.ox.ac.uk>

Over relatively quiet 10mb/s network, I can get no more than 830k/s
ftp, where 2.1.8x were doing only about 720k/s. 2.0 and previous
2.1 would often get upwards of 1mb/s.

Local throughput is a lot better -- up to 7.5mb/s from about 3mb/s
on .89; there's always a stall after about the first 25k, though --
is this related to the bandwidth problem?

I have things cranking a bit more at the moment. BTW how are you
measuring localhost thruput? If with lmbench, run it a few times
before you come to numerical conclusions because:

1) 1.[01] lmbench's bw_tcp did a quick write and could be suspect
to general noise during connection startup. Best bet here
is to run it a few times, or give it a buffer size arg such
as "bw_tcp localhost 20m"

2) 2.0-alpha lmbench's bw_tcp acts a bit hokey to me, it tries to
increase the buffer size until the noise goes away. The buffer
size increment scheme is not always fool-proof. Sometimes it
chooses a buffer size, that with the sockets send buffer size,
will cause a very tiny send packet to be generated. So you'd
see on the wire:

full sized frame
full sized frame
frame with 32 bytes

or something like this. I've had good luck with again giving
it the "20m" arg and running it a few times.

Later,
David S. Miller
davem@dm.cobaltmicro.com

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