Cheetah3D and the 8-core

[Chris]

Hi all,

Bravo to the Cheetah3D's creators for their work, however I have two questions on points disturbs me a lot:

- I would like to know if the future version of Cheetah3D will manage
the sixteen threads of the mac pro 8-core (Sunflow already does)

- Does the limitations of sample lights disappear?

Cheers,


Chris.

[podperson]

1. C3D has one creator (Martin) -- I guess Frank might make it count as two since he contributes to the UI
2. Just out of curiousity -- is there any performance benefit to splitting rendering into multiple threads on a single core (via hyperthreading) -- as far as I can tell it would actually slow rendering down: this isn't the purpose of hyperthreading
3. What limitatons of sample lights?

[Chris]

Hi podperson,

Thanks to Martin for this soft

- This means that my 8-core will do nothing in Cheetah3D?

- The post for the sample limitation is here:

http://www.cheetah3d.de/forum/showth...=light+samples

Bye,

Chris.

[Martin]

Hi,
all your 8 physical cores of your Mac are utilized. But the new Xeons have 16 logical cores that is right. But that just means that they can run two threads very efficiently on one core. What I've read the usage of hyper-threading can return a speed up of something between 0-50%.

Cheetah3D 5.0 will support all 16 logical cores but since I have no new Mac Pro I couldn't measure the speed up yet. I'm also quite curious.

I haven't worked on the max. light samples yet. Sorry.

Bye,
Martin

[podperson]

I'd be curious to find out if hyperthreading helps in this case. It may very well not help unless an operation is I/O bound (e.g. video stuff) because the idea is that a thread which stalls on a synchronous task can surrender to another thread on the same CPU without the full cost of a context switch.

Back when Intel introduced hyperthreading (on the PIV) it actually slowed down the performance of well-written single-threaded applications.

Also, the Corei7 and Xeon equivalents are odd beasts -- they will overclock themselves if they don't need all their cores...

[Chris]

Hi Martin,

That is a good new, thanks for your work.

I will tell you the results.

Christian.

[ricoh]

If you render two or more pictures at the same time Cheetah uses all sexteen cores.

I can render my test-scene in 159 seconds on 8 logical cores, but i can render two test-scenes at the same time in 205 seconds on 16 logical cores. If Cheetah uses all 16 cores it speed up the rendering.

[Chris]

That's true Ricoh, I honestly thought my 2X8-core would be faster.

Chris.