Hyperthreading/Twin CPU question 1

[stduc]

Same Machine as in thread

http://www.tek-tips.com/viewthread.cfm?qid=1197410

XP shows it as having 2 CPU's. But opening the box shows it patently doesn't.

It does have hyperthreading technology though. This seems to cause XP to show two CPU's and also show (in taskmanager) a high level of idle % when the machine is obviously busy.

I was wondering if anyone could point me in the right direction to read up on this. Also, is there any point in using this technology on XP home?

 

[cdogg]

Here's a basic rundown:

http://en.wikipedia.org/wiki/Hyperthreading

There are a ton of sources all over the net you can search for. Tom's Hardware is a good stop to make on the subject.


Just know that the use of hyperthreading is a built-in function for the CPU you have. It can be turned off. In "some" instances, it can actually improve performance using a "divide and conquer" scheme when a specific app supports mult-threading. It can also help somewhat when you have many apps open at once.

It's not a huge benefit, but it's better than nothing. That's the bottom line. Obviously the newer CPU's that actually have two separate cores take this concept to the next level.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[stduc]

Sorry, I should have been clearer.

I googled and found lots of theory. I think I have grasped the basics. I thought that someone here could point me at the more practical side of things - especially with reference to XP.

I have come to the tentative conclusion that as the O/S doesn't really support hyperthreading it's a bit of a waste of time. I have also read some stuff that says you should turn it off (which the BIOS permits).

So I kind of wondered if anyone here had personal experience they may care to pass on.

Thanks.

 

[cdogg]

Your conclusion that XP Home doesn't "really" support hyperthreading is false:

http://support.microsoft.com/default.aspx?scid=kb;en-us;810231

(officially from Intel)

http://www.intel.com/support/processors/sb/CS-017343.htm

So in task manager, do you see two CPU graphs or just one? If you have two and both show high levels of idle %, make sure you are running a CPU-intensive benchmark to be sure (like Sisoft Sandra). Remember, just because your hard drive might be chugging like crazy, doesn't mean your CPU is working very hard.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Albert Einstein
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[TonHu]

Well, running our heavy load Java app, on a hyperthreading CPU, compared to that same system running with HT disabled, wins me about 10% in performance. I'm quite sure I'm NOT going to turn it off again ;-)

HTH
TonHu

 

[stduc]

Many thanks for that cdogg. I didn't notice those links in the 24 gazillion hits I got from Google. LOL. My conclusion is that the CPU is wasted on the rest of the hardware!

 

[Sympology]

Oddly enough Intels Hyperthreading often used to screw up Intels Dialogic (telephony) boards.

Only the truly stupid believe they know everything.
Stu.. 2004