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immolatus
06-13-2009, 12:00 PM
Hi,

I'm trying to render an animation and for the first time I had the pleasure to see for myself why people call mental ray mental delay. I'm trying to render my animation with motion blur. I tried using both flavors (rapid and normal one) but every time towards the end of the render, mental ray stops using my 7 cores and continues with only one ( I have 8 cores on my workstation). It takes ages in the end to render the frame because of it. I tried playing with bucket size but it got way more slower. This is the first time that I encountered something like this. I really need help.

P.S I also tried switching from raytraced shadows to depth map shadows.

klingspor
06-14-2009, 12:14 AM
mental ray renders in tiles, so naturally near the end of a frame only a single tile may be left to render. But nonetheless only one core will render it, no matter if the others are busy or not since MR doesn't dynamically adjust the bucket size.

Depending on the contents, obviously this last tile may appear to take longer than when all cores are rendering simultaneously.

That's probably what you are seeing.

Hamburger
06-14-2009, 04:11 AM
yes, but sometimes this is exaggerated.

i recently had a scene where the frame would take two minutes to render up to 99.3%, then the last .7% would take up to 20 minutes in some instances, but would roughly be usually 11 minutes.

Not a fun thing to try and fix.

luckily this happened to me only to one scene, but unfortunately immolatus - I could never find a fix for it.

How long is this last bucket rendering for?

MasterZap
06-15-2009, 06:57 AM
The "quick and easy" fix for this is to render in smaller tiles.

/Z

wizlon
06-15-2009, 01:44 PM
Where/how do we change the tile size?

cbamber85
06-15-2009, 03:59 PM
Where/how do we change the tile size?
In the MR render/batch options under 'Task Size' in the Parallelism section.

@HamburgerTrain
Somebody on another thread mentioned the latest Maya SP1 which has a fix for a rendering issue where not all the cores were being used when HT was turned on, could this be affecting you?

Hamburger
06-16-2009, 11:20 PM
I'm using 2009 x64 SP1a, however I think it's now just a problem with my network (even though it's 1gps).

The problem scene doesn't have the problem when rendered locally. In fact for this particular scene it's faster to render locally than to use two comps. :shrug:

klingspor
06-16-2009, 11:31 PM
I'm using 2009 x64 SP1a, however I think it's now just a problem with my network (even though it's 1gps).

The problem scene doesn't have the problem when rendered locally. In fact for this particular scene it's faster to render locally than to use two comps. :shrug:What texture format are you using?

I remember having this problem at some point but I don't know how we solved it... just that the texture format was the culprit.

techmage
06-17-2009, 04:05 AM
This is an issue to every bucket renderer, vray, modo, final render. The last bucket will only use 1 thread, so it always ends in one thread.


There is however one thing I noticed about mental ray as of recent. That is, if your using frame buffer cache mode, or I think even just virtual mapped mode, mental ray only uses 1 thread to stitch together the framebuffer to output the final image. And sometimes this can take quite a bit of time. On a 5000 pixel wide image it took something like 5 minutes one time. I imagine that if your rendering in full HD with multiple passes, it could easily take a bit of time.

Although my observations on that were very limited, just one test scene, so I could be completely wrong.

Hamburger
06-19-2009, 03:32 AM
What texture format are you using?

I remember having this problem at some point but I don't know how we solved it... just that the texture format was the culprit.

The automatic convert-to-map-on-rendertime feature.

I never know what it is that was causing it but the sequence is now finally finished and the rest of my shots are behaving properly.

Its just not enough time to pinpoint what was going on.

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06-19-2009, 03:32 AM
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