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View Full Version : multi-threaded rendering efficiency

e[dub]
05-04-2007, 09:14 PM
I just got an 8-core mac pro, and I'm noticing that towards the end of my rendering (arch vis), my core usage goes down to 1 core for the remaining ~10% of the rendering.

It seems there's a point, at which, the cores no longer get part of the remaining rendering distributed amongst them. This results in a fast first ~90% of the rendering, when all core are running at 100%, but that last ~10 takes longer than the first 90%!!.... what's going on?

Has anyone else observed this? If not, then I guess I'm sending back my "Dr.Octocore" :(
Per-Anders
05-04-2007, 09:18 PM
Is this during when it's doing post effects? Post effects mostly aren't multithreaded.
e[dub]
05-04-2007, 09:20 PM
no post effects.
kromekat
05-04-2007, 09:24 PM
I have noticed that it trails off at the end to a few cores, whereas during the main part of the rendering, it maxes out all 8. - It didn't seem to be as much as 10% to me though, more like 1-2% from the end, but it didn't cause any concern, since it overall rendered hugely fast.

I wasn't using any post effects either.

Adam
e[dub]
05-04-2007, 09:27 PM
well, wether it's 10% or 2%, the fact that that remaining part takes longer than the initial part, because only one core is used, is what is frustrating me.
JIII
05-05-2007, 03:08 AM
on my lil two core machine i also have noticed that sometimes it should "pick up" and it doesn't. I'm sitting there like... wtf mate, I know it's only got a little bit left but the other line was traveling faster anyhows.

Don't really know why it'd do that.

-John
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05-05-2007, 03:08 AM
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