[Amarok]

Hi,

I did a little test with both PC and Mac, and I almost sure that the Mac don't use it's full power for render with Maxwell.

while render a simple scene, for the PC (AMD 3000+ 2Ghz, 512MB) I't took 2h to finish the render. in the meantime the PC barely move, and it was unused, the process was felt very well.

for the Mac (G5 2.7Ghzx2, 3GB ram) it took 1h 30m. faster, but without any proportions, and the machine was able to run any other tasks without any problems (photoshop, illustrator, etc.).

for this test I leave both machines to render without running any tasks in the background, and the threads was set to 4.

any idea why the Maxwell not using the full power on Mac ? or maybe I'm missing something in rendering setting ?

[dex001]

Hi Amarok

same problem here:

same scene on a centrino 1.7 ghz on the other side a dual 2.5 ghz powermac with much better memory setting.

The pc finishes faster than the mac but cpu monitor shows full cpu usage.
We want to upgrade our setting through a renderserver, but for now I put it on hold to wait for the intels coming to MacOSX.

With mental ray I could not see this big performance gap.

Would be very helpful to get a statement by the developers here !

Thanx

dex001

[Amarok]

Did you look at the activity monitor?

yes, I did. it shows 100% processor usage for both processors!

With mental ray I could not see this big performance gap.

I did the Cinebench test on both machines, and the Mac was 120%(!) faster from the AMD, this gap make sense !

Maxwell NOT using the Mac's full power, even if it's look like it is in the activity monitor, no doubt about it!

[dex001]

I did another test with just one thread, the activity monitor shows again that both processors are in full use without any change in timings....strange isnt it ?

besides that I am am not able to start two renderings at the same time like on the PC...is this related to the problem ?

dex001

[JesperW]

The reason why the Mac is more responsive has nothing to do with Maxwell not using the full CPU power. It has to do with the operating system scheduling functions, and latency.

MacOs is a modern kernel with priority for IO-bound threads (think interactive processes) over CPU-bound ones (like Maxwell is). The Windows NT kernel is a tired old beast, with very little such optimisation. (WinXP also runs on the NT kernel)

This does not, however, explain why the PC is faster. The only thing I can think about here is that Maxwell uses SSE2 instructions well on the Pentium, but fails to utilize Altivec in the PowerPC. IF that's the case, Next Limit is using either a severly retarded compiler on the Mac. Or maybe they even went and handoptimized some crucial subroutines on the PC?

/j

[dex001]

thank you for the explanations Jesper, but I guess performance differences of 100% and more are close related to maxwell since the power macs have pretty good processors.

let's wait for holy friday

dex001