Multiple Threaded Rendering???

anyone have an idea about this:

my home system running win xp x64, an amd64 x2 processor, runs both cores at 100% with "run multiple threads" checked.

my laptop, running win xp x64, an intel core 2 duo processor, still only runs one core at 100% with "run multiple threads" checked.

any trick to making it hit both cores?

My Dual Processor PowerMac G5 barely goes above 100% overall utilisation with or without run multiple threads enabled. With it enabled it does seem more responsive and squeezes some more fps out, though if rendering has trouble (e.g with spheres being ridiculously laggy now as mentioned above) then it still slows down the game. Seems like multiple-threads isn't fully de-coupling graphics from the rest, I'm thinking perhaps that Level Of Detail and Occlusion Culling maybe aren't being calculated in their own threads.

But yeah, on my Mac running OS X, SL utilises at most 102% over 13 threads, which isn't very good as I had around 60% of my processor idle and no performance restrictions in place, I'd have loved to give SL 160% CPU time if it made it run faster
I'm thinking the run multiple threads option still hasn't really separated that many things from the main system, as it still gets bogged down very easily despite large amounts of unused processor speed.

The Run Multiple Threads option does not of course multithread the renderer which is MOST of the cpu time taken up by SL. It mere means that some non rendering threads are allowed to run during rendering. It adds a few fps to my machine but not too much.

Some day the renderer and open gl itself may be fully multithreaded and finally SL can really rip up the sheets. Really id should be by now hell several years ago! But OpenGL development is glacially slow and though Mac will soon have a multithreaded open gl implentation, if SL does not multithread it's rendering routinees then it won't make any difference.

But for now, the Run Muptiple Threads does not really speed things up too much if at all. (3-4 fps at 40 fps for me)

There seems to be a difference between dual core and HT processors.

http://www.intel.com/personal/desktop/dualcore/demo/popup/demo.htm

In a HT system you can never get true 100% processor utilization due to some shared resources between threads. The system that measures processor usage is also not perfect in that it is actually measuring the time that is not used.

Internally I think the windows task switcher uses QueryPerformanceCounter() before and after a task is ran for a time slice. This means that it can't tell how efficiently the thread is using the processor, just that the thread used it for set amount of time.

Althought the CPU untilization numbers are bogus, I actually get BETTER prformance on an HT processor in HT mode than in uniprocessor mode. The threading performance is better, and even a multithreaded program like SL which is very hevily weighted in a single thread still performs better in HT mode than not. So even though the cpu performance of SL on an HT processor is rarely much over 50% on windows in the task manager it is infact using as much as 90-95% of the cpu. The reporting is just wrong.

SL runs about 5% faster in HT mode than uniprocessor mode on my machine.

Amusingly on Linux HT processor cpu untilization is equally bogus but in the opposite direction, you can have two programs with 100% untilization...

One app at 100% CPU utilization in a single thread:
Linux -
Prog A - 100%
Windows -
Prog A 50%
In this case Linux more correct

Two single threaded apps eating half the cpu each totaling 100% CPU utilization:
Linux -
Prog A 100%
Prog B 100%
WIndows -
Prog A 50%
Prog B 50%
In this case Widows more correct

HT tech really messed tiwh the performamnce monitors but it does actually work nicely, short of a dual core anyway.

Thought I'd post a lil' pic of what I'm seeing, which is First Look using BOTH cores on a Dual Core CPU. It spiked a bit when I hit "Print Screen" but then settled back to 50% each core.

It looks the same for my like on Tod69's picture. Despite a few minor peaks, which might be calculation errors, SL utilizes 50% of my amd 64 X2 on XP using Firstlook, and nothing more. With and without dual core optimizer and with the latest amd drivers installed. Of course it runs smoother then using a single core processor and activating this multithread option *seems* go give some more fps, but the cpu is still doing half of it's power. And this is no calculation error of the taskmanager, which can easily be tested while doing some serious multitask performance.

I am really wondering if anyone gets more out of his dual cores on windows (or linux) then these 50% for SL because some of you are writing about 100% utilisation of the cpu. It really sounds like some of you managed to fully utilize their multi cores. If so... please please please what did you do??? (on which cpu and operating system, and... HOW??)

i'm using windows xp x64, its a 64bit version of windows made for dual core, nobody seems to know about it. but it might be why its Using 100% on my amd64 x2 system.
also, under power settings, you need to select the "minimal power management" profile.