Render slowing down

[JakeMM]

Hi,

I'm using a Dual Core Hyper Threaded MacBook. SketchUp will usually show 400% while I am rendering, but for some reason, it now fluctuates between 100% and 400%; averaging about 300%.

It seems that it fluctuates while I am using the computer for other things while it is rendering. It doesn't reduce the CPU load by the amount that I need, but rather it frees up a lot of the processing power and makes it "idle", should I need it for whatever else I am doing.

I am not near my RAM limit, and nowhere near any temperature limits.

I'm sure it didn't used to free up CPU processing power as a buffer should I need it. Is this something to do with Twilight, or is it something Apple has changed in an update?

I can understand the thought process behind this - the computer will run flawlessly, but it's at the expense of slower rendering times (which I don't want!). Do you have any ideas as to whether this behaviour can be easily changed?

[Fletch]

When was the last update to the O.S.?

[Chris]

Twilight Render runs the render engine at a Low priority. In theory this means that the OS will schedule other things ahead of the render (if you are browsing or typing a paper or whatever). The render takes the lowest priority.

How the OS does that is... however they want to do it. And probably subject to change. Did apple change OSX so that it monitors your usage and tries to guess what you might want to do and do it for you? Probably. I would say there is a very high chance of that.

[JakeMM]

There's updates fairly regularly on Mac, every couple of months or so. I've been doing a lot of work purely in Layout and SketchUp, so I can't pinpoint when this issue started happening.

Chris, I've just been running Folding@Home today on my MacBook. This uses all 4 threads and is holding completely steady at the maximum usage it can. The Mac isn't leaving any of the CPU at idle, so it shows it can still run at maximum usage if it wants to. (I always turn off F@H when I'm rendering).

Is it possible to increase the priority of Twilight Render, and is that something I can do myself? These dips are increasing my render times by quite a lot!

[Fletch]

Change thread priority on Mac OS

[Schacht]

Does changing the thread priority mess with any other settings or is it completely safe to do?

[Fletch]

There's really only one way to find out - in my experience (mostly on windows o.s.) changing thread priority has been safe to do.
If you close out of all other apps you can first, then change thread priority you minimize chances of issues.