[SLUG] Hyperthreading

[Rev Simon Rumble <simon@xxxxxxxxxx>]

I have an Intel Xeon 3 gig CPU and have hyperthreading turned on in the 
BIOS.  I've been trying to work out what the advantages and 
disadvantages of this are.

The CPU appears as two CPUs to the machine, which means that 
non-threaded apps don't appear to use the whole CPU.  Is this a correct 
assumption?  For example, using Devede to convert video, the transcode 
process only uses 50% of CPU in top.  If I run another CPU-intensive 
process, the CPU usage in top goes close to 100%.

So would I be correct in assuming that hyperthreading is useful for 
keeping the system responsive under load, but if running single-threaded 
CPU-intensive processes, it'll run faster without hyperthreading?

This machine can actually take another CPU, but finding a suitable one 
and the matching fan and shroud (Dell) doesn't seem to be easy.

-- 
Rev Simon Rumble <simon@xxxxxxxxxx>
www.rumble.net

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