[KLUG Members] SMP and ACPI in 2.6.12

[Kevin Mitchell]

On Tue, 28 Jun 2005, Chester Wisniewski wrote:
<snip>
>
> The bigger question is, why would you want to enable hyperthreading?
> Have you properly tested your application performance? With the
> applications we run our software on it is anywhere from 7% to 18% slower
> with it enabled than disabled (on 3.4Ghz XEON CPU's). Its particularly
> brutal on database servers.
>
> Chet
>

The servers in question are running Sendmail and from what I've read 
Sendmail benefits from hyperthreading.  No, I haven't benchmarked the 
difference, but I'm planning on doing so now that you mention it because 
it sounds like fun. :)  I'll make sure to post the results to the list.

Doing a quick search online about Linux and hyperthreading got me to this 
page:

http://www.2cpu.com/articles/41_4.html

It seems to show that (at least in this benchmark) that MySQL benefits 
quite a bit from hyperthreading.  What databases are you running that you 
see a slower performance?

Also, are there any guides or benchmarks that you're aware of that make 
suggestions as to using hyperthreading with different applications?

Kevin