Netpref results on SMP machine

[Robert Watson]

On Wed, 23 Aug 2006, kumaresh pandian wrote:

>    I ran the netperf test of TCP_STREAM for 35 hours on a FreeBSD 6.1 SMP 
> machin and a FreeBSD Single Processor machine which has the following 
> configurations

There have been a number of reports of significantly reduced loopback IP 
performance on 6.x as a result of preemption, which can result in context 
switch thrashing on some systems.  There has been some amount of discussion of 
this problem, in particular at the recent BSDCan developer summit, and there 
are tentative plans for a fix.  You might want to try disabling preemption in 
your kernel configuration to see what the impact is.  However, as you're not 
doing side-by-side comparisons in your tests, it's hard to compare the results 
in order to decide what problem may exist.


Robert N M Watson
Computer Laboratory
University of Cambridge