Does OS X use Hyperthreading?

[space-time]

my work laptop (Dell M4500) has a dual core i7 CPU. With hyperthreading enabled, I see 4 "CPUs" in Task Manager (XP) and I get a geekbenck score of ~4900

if I disable hyperthreading, I see only 2 CPUs and I get a lower score, ~4200.

But I don't recall any of these settings on OS X. How does OS X deal with hyperthreading?

On real Macs we don't even have BIOS (to turn hyperthreading ON and OFF). For those that built high end hackintoshes, do you use hyperthreading? does it make a difference in OS X?

Thanks

[Lew Zealand]

Yes it does. Call up Activity Monitor and see how many CPUs are detected.

[M A V I C]

Macs use Hyperthreading. It makes a difference depending on the app you're using. As far as "we don't even have BIOS" - that's not really accurate. We have the successor to BIOS - EFI.

Most apps I use don't perform much better with HT, so I opted for a processor without it.

[wickedsteve]

Apple wrote:
Hyper-Threading is now standard on every MacBook Pro. This technology allows two threads to run simultaneously on each core, so Mac OS X recognizes eight virtual cores on a quad-core processor and four on a dual-core processor. When you’re running multiple applications at once, the processor spreads tasks more evenly across a greater number of cores.

http://www.apple.com/macbookpro/performance.html
www.apple.com/macbookpro/performance.html

[space-time]

Lew Zealand wrote:
Yes it does. Call up Activity Monitor and see how many CPUs are detected.

my wife has a late 2007 MacBook (Core 2 Duo) and in Activity Monitor I see 2 CPUs. I would expect to see 4 like on my XP laptop.

[ADent]

Handbrake will use all those cores - I get around 700% CPU usage of my desktop i7.

[JoeH]

space-time wrote:
[quote=Lew Zealand]
Yes it does. Call up Activity Monitor and see how many CPUs are detected.

my wife has a late 2007 MacBook (Core 2 Duo) and in Activity Monitor I see 2 CPUs. I would expect to see 4 like on my XP laptop.
The Core 2 Duo CPU's do not have Hyper-Threading available, it is not an issue of whether it is enabled or not. So you see all the CPU's that you should or can on your wife's MacBook.

[Panopticon]

what JoeH said. No C2D-M processor has HT. Several also lack VT.

Intel specs table for C2D-M

[space-time]

Ah, thanks. I remember HT was quite old (early 2000s) and I though that all CPUs since then had HT. I was not aware that some CPUs did not have HT.

Thanks folks

[M A V I C]

ADent wrote:
Handbrake will use all those cores - I get around 700% CPU usage of my desktop i7.

Handbrake will probably perform the same on a processor with or without HT enabled.