hyper threading preformance

[finalbarrage]

so, an i7 has 4 cores, but 8 threads, and as far as i know, its cause the CPU is emulating the 4 extra cores.

 

my question is, would an i7 preform better without the hyperthreading when dealing with things such as 3d rendering?

[DimasRMDO]

Well, the Hyper-Threading is the one that make i7 perform better....

 

No, it'll perform worse....

[Pool]

Nope, reducing the amount of core doesn't mean you're going to have twice better cores. 

[Eniqmatic]

Do you think they would make i7's and charge more than i5's if the performance was worse?

[Dzzope]

HT increases the usage of the cores. Meaning they are working more of the time. 3d rendering and such is exactly when you want this.

If you were overclocking and performing single-threaded taks, then you could see an increase.

[finalbarrage]

Nope, reducing the amount of core doesn't mean you're going to have twice better cores. 

i never said reduce the amount of cores, but using 1 thread for each core instead of 2.

 

since i was thinking, when dealing with 3d rendering, the CPU is running at stock 100%, so if it could run at 100% without HT..

 

ur not using less of the CPU power, but you dont emulate the extra cores, witch means more power would be focused on the actual rendering? 

i dunno, it makes sence to me. 

its kinda like using half of your core for rendering in hyper-V, and the other half on your actual computer. witch in fact would slow things down.

i see HT as a kind of "virtual core" just like hyper-V creates a "virtual computer".

[Dzzope]

 

ur not using less of the CPU power, but you dont emulate the extra cores, witch means more power would be focused on the actual rendering? 

i dunno, it makes sence to me. 

Nope, HT doesn't emulate a core, it just runs another thread at the "same" time (they actually switch back and forth), the thing is a core will always have down time running one thread while it puts and fetches the next instructions to run, HT lines up additional work in a separate thread to run on that core.. Each thread will run slower but since 3d rendering and such use multiple threads well it's a net gain.

 

This is why you sometimes see an i7 post marginally worse scores in gaming benches than an i5.

 

BTW, thats not official "how it works" but my best simple explanation of how I understand it works

[i_build_nanosuits]

ur not using less of the CPU power, but you dont emulate the extra cores, witch means more power would be focused on the actual rendering? 

its kinda like using half of your core for rendering in hyper-V, and the other half on your actual computer. witch in fact would slow things down.

i see HT as a kind of "virtual core" just like hyper-V creates a "virtual computer".

 

That's not at all how it works.

 

HT is nothing more than clever advanced scheduling of the threads to allow the CPU cores to work harder with less downtime when possible.

Turning it off won't make CPU cores go any faster...CPU thread #1 will take the same time to compute regardless of if HT is enabled or not.

 

 

http://en.wikipedia.org/wiki/Hyper-threading

For each processor core that is physically present, the operating system addresses two virtual or logical cores, and shares the workload between them when possible. The main function of hyper-threading is to increase the number of independent instructions in the pipeline; With HTT, one physical core appears as two processors to the operating system, which can use each core to schedule two processes at once. In addition, two or more processes can use the same resources: if resources for one process are not available, then another process can continue if its resources are available.

[Glenwing]

i never said reduce the amount of cores, but using 1 thread for each core instead of 2.

 

since i was thinking, when dealing with 3d rendering, the CPU is running at stock 100%, so if it could run at 100% without HT..

 

ur not using less of the CPU power, but you dont emulate the extra cores, witch means more power would be focused on the actual rendering? 

i dunno, it makes sence to me. 

its kinda like using half of your core for rendering in hyper-V, and the other half on your actual computer. witch in fact would slow things down.

i see HT as a kind of "virtual core" just like hyper-V creates a "virtual computer".

The whole point of Hyperthreading is that you can't really run your CPU core at true 100%. There are always some inefficiencies, some unused cycles depending on if one thread has stalled momentarily due to various reasons. Hyperthreading increases efficiency by allowing the CPU to work on another thread if the primary one is stalled. If you didn't have hyperthreading the primary thread would still be stalled, it isn't going to go any faster.