When is it time to turn off HT

Question

When is it time to turn off HT

Robert Koros

SSC Enthusiast

Points: 176
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August 26, 2005 at 8:20 am

#165856

Good morning,
Moving to a new server with 4 processors and I am wondering when, or perhaps, if there is a time to turn off hyperthreading?
SQL Server 2000 SP4 with the AWE hotfix installed.
24GB RAM
Windows 2003 SP1

Viewing 8 posts - 1 through 7 (of 7 total)

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peterhe SSChampion Points: 11469 More actions · Answer 1

When turing HT on, I experienced performance degradation in w2000 with SQL 2000 enterprise edition. So my suggestion is on W2000, turn it OFF.

On W2003, windows has better support for HT, maybe leave it on is not a bad idea. You can make your decision by doing some benchmark test because the number of users, transaction type affect this decision, e.g. if you have lots of small concurrent transactions, leave it on may be better.

AJ Ahrens SSC-Insane Points: 20676 More actions · Answer 2

AFAIK up until W2K3 the O?S would not use it. So unless you are on Windows 2K3 it won't do anything but, possibly slow you down.

Good Hunting!

AJ Ahrens

webmaster@kritter.net

Robert Koros SSC Enthusiast Points: 176 More actions · Answer 3

I have been running HT on W2003 for a while now without any issues or degradation, probably due to the number of small transactions. It is supporting an ERP so there are a lot of little calls to the database with the occasional larger set.

I may just leave it on, no need to fix something unless it is broken. Appreciate the help.