Xeon/P4 hyperthreading

[Lennart Sorensen]

On Sun, Oct 12, 2003 at 04:18:40PM -0400, William Park wrote:
> If there's anyone here with P4 or Xeon with hyperthreading and SMP
> kernel, can you compile kernel
>     make bzImage > /dev/null
>     time make -j 3 bzImage > /dev/null
>     time make bzImage > /dev/null		
> and post the elapsed time for the last 2 commands.
> 
> Thanks.  It's time for upgrade, and I would like to get some feel for
> hyperthreading in P4 and Xeon.  

I would love to do it, but I don't think the database users would
appreciate it.  It probably wouldn't give the right results anyhow,
given it has 4 xeon's in it.  As far as I can tell it looks as though it
gives about 20 to 30% extra out of the cpu to have hyperthreading
enabled.  On 2.6 it might be more (at least on multi cpu machines) since
it has a better schedular that knows about related cpus.

Lennart Sorensen
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