<p>My project has some money to spend before the end of the fiscal year and we are considering replacing a Sun-Fire-V490 server we've had for a few years.  One option we are looking at is the <a href="http://www.sun.com/servers/coolthreads/overview/index.jsp" rel="nofollow noreferrer">CoolThreads</a> technology.  All I know is the Sun marketing, which may not be 100% unbiased.  Has anyone actually played with one of these?</p>

<p>I suspect it will be no value to us, since we don't use threads or virtual machines much and we can't spend a lot of time retrofitting code.  We do spawn a ton of processes, but I doubt CoolThreads will be of help there.</p>

<p>(And yes, the money would be better spent on bonuses or something, but that's not going to happen.)</p>

IIRC The coolthreads technology is referring to the fact that rather than just ramping up the clock speed ever higher to improve performance they are now looking at multiple core processors with hyperthreading effectively giving you loads of processors on one chip. Overall the processing capacity available is higher but without the additional electrical power and aircon requirements you would expect (hence cool). Its usefulness definitely depends on what you are planning to run on it. If you are running Apache with the multiple threads core it will love it as it can run the individual response threads on the individual cpu cores. If you are simply running single thread processes you will get some performance increases over a single cpu box but not as great (any old fashioned non mod_perl/mod_python CGID processes would still be sharing the the cpu a bit). If your application consists of one single threaded process running maxed out on the box you will get very little improvement on a single core cpu running at the same speed.
Peter
Edit:
Oh and for a benchmark. We compared a T2000 in our server farm to our current V240s (May have been V480's I don't recall) The T2000 took the load of 12-13 of the Older boxes in a live test without any OS tweeking for performance. As I said Apache loves it :-)