Subject: Linux single copy pipes
To: None <firstname.lastname@example.org>
From: John Fremlin <email@example.com>
Date: 05/07/2001 18:17:01
Manfred Spraul made a patch for single copy pipes under Linux. For
example, on my 300 MHz AMD K6-2, linux-2.4.4,
Brett McCoy <firstname.lastname@example.org> writes:
> cpu0: Intel Pentium Pro (686-class)
> total memory = 127 MB
Brett's CPU is slower than mine (only 200 Mhz) and I have more memory
(320Mb) so the comparison is unfair. Unfortunately I don't have a
native NetBSD install on my PC so I can't do it properly.
Without single copy:
> Pipe bandwidth: 48.36 MB/sec
With std lmbench 2beta3 I get about 45 (+- 2) Mb/s.
> Pipe latency: 65.5195 microseconds
With std lmbench I get about 27 (+- 1) usec.
> Pipe bandwidth: 194.09 MB/sec
About 59.5 (+-0.6) Mb/s :-(
> Pipe latency: 43.2424 microseconds
About 22 usec.
So from this very crude comparison Linux rules the latency, but the
loses bigtime on the single copy bandwidth (did you people hack
lmbench for a bigger request size?)