Dual CPU drivers: Any benefit now from enabling HT?

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yevaud

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I'm running windows 2K (not HT friendly) and was wondering if anyone had seen a boost from the new dual CPU enhanced drivers on intel machines that had HT enabled vs. disabled. If it's quantifiable, it might help me justify an XP 'upgrade'.
 
When HT is enabled on an XP machine, the system 'sees' two processors. If an app is multithreaded, both of these virtual processors can get loaded- but in single thread apps only one gets the load. This is why I'm asking the question. I know that an HT proc is not a true 'dual core' chip.
 
I have honestly seen no improvement with the Cat 5.12's. Not that I can see with my own eyes anyways.
 
yevaud said:
When HT is enabled on an XP machine, the system 'sees' two processors. If an app is multithreaded, both of these virtual processors can get loaded- but in single thread apps only one gets the load. This is why I'm asking the question. I know that an HT proc is not a true 'dual core' chip.
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No, it's been shown that HT for dual core drivers doesn't work like real dual core.
 
Quote from the release notes:

"Catalyst 5.12 improves a variety of CPU-bound performance cases when an ATI product is installed in conjunction with a dual-core or hyperthreading CPU."

That being said, I didn't notice anything dramatic on my HT P4...
 
I have to agree with fromage...HT is NOT dual core. The system does look like it sees two cores, but it does not really 'SEE' two cpu's and the CPU's will not handle two seperate threads. The CPU does report loading as two CPU's but you will never see anything greater than 100% total load as a combined result of the two cores such as if one core is operating at 80%, the MAX the other core will be at is 20% and vice versa, both could show 50% but never above that amount simultaneously.

With a true dual core CPU, you actually can simultaneously load both cores to 100% each with seperate threads.
 
BBA said:
I have to agree with fromage...HT is NOT dual core. The system does look like it sees two cores, but it does not really 'SEE' two cpu's and the CPU's will not handle two seperate threads. The CPU does report loading as two CPU's but you will never see anything greater than 100% total load as a combined result of the two cores such as if one core is operating at 80%, the MAX the other core will be at is 20% and vice versa, both could show 50% but never above that amount simultaneously.

With a true dual core CPU, you actually can simultaneously load both cores to 100% each with seperate threads.
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hate to tell you, but due to the crappy monitor in windows XP, even WITH two CPUs, you won't see more than 100%. Actually depending on which patch level you are at (haven't checked if it's been fixed) you may never even see 100%. The monitor got fairly borked at some point for XP.

Unless the drivers are doing some real low level snooping, they probably attempt to use HT to offload some work, but you won't get much help from HT just because it seldom represents a lot of free CPU when you are running a game. Especially if you aren't at the bleading edge of CPU power.

Having a whole second CPU free might be another matter though. Haven't tried them yet though.
 
My thought is that with multithreaded aware drivers hyperthreading is not giving that big of a boost to preserve a performance differents, and the only time you do is with a real dual core CPU...
 
raz-0 said:
hate to tell you, but due to the crappy monitor in windows XP, even WITH two CPUs, you won't see more than 100%.
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With two real cpu's (as in dual core) you will see both cores reaching 100% with multithreaded applications.

With Hyperthreading you wont, because hyperthread does not do multithread applications. It simply breaks up a single part of a threads predictions into two core areas to help reduce misses in prediction values. It actually adds a latency that slows down a lot of applications.
 
I noticed a good increase in performance in FarCry, but nothing else. I do think it was geared more toward dual-core CPUs, but there are some performance benefits for those of us with HT...
 
arabdon1203 said:
hyperthreading gets boosts in multi threaded apps :rolleyes:
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Actually no. In multithreaded apps when we test dual and quad cpu servers, enabling hyperthreading reduces performance.

It only boosts certain types of processes, single threaded processes that benefit from predictive branching.

Read my type...a single hyperthreading CPU is NOT able to handle multithreading.

Period.
 
Surely you will only see any noticable improvements on games which are very CPU depedant. An example of one is FarCry (hence why you noticed it).
Even so, its not meant to be a huge boost (prob about 5% - 10% at best).
 
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