CPU usage goes way up on 5.1 when memory is added

[Richard G. Roberto]

On Fri, 23 Jan 2004 15:54:44 -0800, Kris Kennaway wrote
> How are you trying to measure this?  Have you tried reverting to a
> GENERIC kernel to isolate one of your non-default options that may be
> causing the problem (or measurement artefact)?
> 
> Kris
Well, measuring it isn't really an issue as the problem is so drastic, 
there's no trouble in identifying it.  I have taken some vmstat and iostat 
data over time that can be used for comparison, but it really isn't 
necessary in this case.  The CPU usage isn't even close to normal with the 
additional memory.

Since this system is in heavy use, I haven't had the time to do a lot of 
trial and error with different kernel options yet.  I will certainly try to 
schedule that soon.  I was hoping that somebody on the list would have an 
idea as to why this happens.  I really can't form a relationship in my head 
between the additional RAM and the strange CPU behavior.  So I was hoping 
someone more familiar with freebsd 5.1 could help me out.  I know that the 
ULE scheduler is still experimental, so that was going to be my first choice 
for rolling back, but I'm still interested in hearing from anyone else who 
may have seen similar behavior.

I'm trying to get this sorted out before my linux zealot friends harass me 
to no end ;-)

Thanks again,

rgr

-- 
Richard G. Roberto
rgr at dedlegend.com