Hyper Threading and XP

[DBF]

I have an Intel processor and MB that support Hyper Threading and it is
currently enable.
There are, however, several graphics programs which I use which apparently
perform better with HT turned off. Corel Graphics Suite 12 is the most
notable fo these.
So my questions:
1) From the point of view of XP, does it hurt to turn HT off in the
BIOS?
2) I mean, will it crash or lock up my system or cause other disasters?
3) Or is it more the same thing as if I added or removed a hardware
item?
4) Anyone have any experience with general Xp performance with HT on and
off?


Thanks,
Dave

Compy Info:
Intel D865GBF MoBo, P4, 2.8GHZ, 512MB
Maxtor 160GB HD, WDC 160GB HD, MysteryBrand CDRW and TDK DVD Burner,
NVIDIA GeForce FX 5200. 128 MB
DSL modem
17" Samsung; 17" ViewSonic monitors
WINXP Home, fully patched and upgraded.
(Well not to SP2 yet; waiting to see what happens with that stuff!)
All software and hardware patches installed and updated; checked monthly.

 

[Nathan McNulty]

1) No, XP can handle that.
2) It should automatically update itself to deal with it.
3) Yes, kind of.
4) I have enabled and disabled HT on the same install many times. No
problems at all, and I don't see a point in disabling it.

What you should do is set the affinity on the application that performs
poorly with HT enabled. Force that application to only see the first
processor and not the second one. Open Task Manager (Cntrl+Alt+Del),
Processes Tab, right click on the process and Set Affinity. There was
also a neat application I read the other day in here that keeps the
affinity settings.

 

[DBF]

Thanks for the reply. I will trouble you with one more question.
Setting the affinity when hper-threading obviously means that the app will
only be using one of the two virtual cpus.
Does that slow things down?
Because the issue which I have encountered, and I should have explained
better, is that HT actually slowed down the particular app and turning HT
off made it work faster.
I might have made it sound like it was a stability issue, which I don't
think iti is.

Thanks,
Dave

 

[Name withheld by request]

You can get the affinity program at toms hardware group.
Here's the URL which explains it:
http://www.tomshardware.com/cpu/20040528/index.html

Here is the URL for the program:

http://www.tomshardware.com/cpu/20040528/images/taskassign.zip

I set it for 3 apps that I run 24/7, for CPU1, and I've noticed a
little snappier load times for everything else, since it isn't hogging
"CPU 0" as much.
Other than Photoshop, and the xp kernal, I don't have anything that
takes advantage of HT, so I guess this little app helps somewhat.

 

[Nathan McNulty]

By setting the problematic applications to CPU 0, and putting other
common tasks to CPU 1 only, you can improve performance. I have not
been able to even measure a difference in any of my applications with HT
on or off. Most software has been updated in a way that it can deal
with HT processors even if they can't utilize it. Whatever programs you
are having problems with, I would look for an update