XEON HyperThreading Vs. MSSQL Enterprise

[Trog Martian]

I have a ProLiant ML350 G3 with dual processors.
Installed: MSSQL Enterprise Edition (25 CAL) on Win2k Advanced Server (8 CPU/25 CAL).

Due to HyperThreading, Win2k sees four processors instead of two.

When under load MSSQL causes ONE of the processor graphs to show more activity than the others in Task Manager -> Performance tab.

Question:

a.
Is MSSQL running at its peak processor performance, even though it "appears" that it is only using half a processor?

b.
Would it behoove me to disable HyperThreading?

[Sunil Jerath]

Hello Trag,
Yes you can disable HyperThreading by going into system properties(F9) and then go to advanced options/features. Highlight the HyperThreading and hit enter. Here you will see Enable/Disable.
Regards,

[Jens Baumann_2 · Accepted solution]

a.
Did you configure MSSQL to make use of all processors? (Start menu-Enterprise Manager-right click on your server-properties-CPU)

b.
According to Intel, W2K does not (yet) support Hyperthreading, i.e. W2K does not know that the extra processors are not "real". Intel recommends disabling Hyperthreading when using W2K. So far, only Win XP supports Hyperthreading:

http://www.intel.com/support/platform/ht/os.htm

There's another thread around here (read it yesterday) with a link to a Microsoft whitepaper about Hyperthreading.

[Trog Martian]

Sunil: Yes. Thanks anyway.


Jens:
a.) Yes. CPU0 through 3 are enabled. Which is part of my puzzlement. Why am I seeing only one "processor" loaded? *shrugs*

b. Yes. I'm now researching the effects of disabling it so that I can run some performance benchmarks. My concern is that Win2k A.S. and SQL both think they were installed on a "four processor" system.


Do you perchance remember the subject of the thread you saw the whitepaper link in? I must've missed it. I've performed searches on MSDN, the MSSQL K-base, Win2k K-base, etc, but haven't found anything really relevant.

Thanks for your help.

[Jens Baumann_2]

The Microsoft whitepaper on Hyperthreading is located at:

http://www.microsoft.com/windows2000/docs/hyperthreading.doc

[Trog Martian]

A tip o' the hat to ye'