View Full Version : rendering musings

10-22-2012, 03:11 PM
so I'm doing a big project.

I've run into 2 things I thought I'd share.

1. I have 2 machines... a late 2010 8 core with 24 gigs of ram, and a Very new MacBook Air, with 4 gigs of ram. I needed to double up my renders in order to make my deadlines, and I thought the macbook air might be able to help just a little. Boy was I wrong. my 4 Core MacBook Air is rendering at about 97% of the speed of the 8 core. Why is this? thare are a couple of reasons:
it seems that the processors in the air, though lightweight, are slightly more advanced than the 8 core's.
the Air uses an SSD. so... paging is ALOT faster.
and finally... I'm using DPKit (WHICH IS AWESOME, NO COMPLAINTS AT ALL) but it seems that DPKit doesn't make use of virtual cores, so the 8Core is effectively an 8Core versus a 16Core for this render. The Air... doesn't appear to have virtual cores at all, so its not affected by the issue.

2. transparency. At some point in recent years I noticed that in some cases, you can use a transparency map that makes a poly completely transparent, and no matter what you do, that polygon will be visible in the render. I don't know what's causing it. the spec is zero, there isn't any color management on the file, the black areas are BLACK, the white areas are WHITE. I'd like to figure out why this is happening and file a Giant Bug in FogzBugs, but right now I'm on deadline.

so, I think my air has found a new purpose... to sit next to me and make a high pitched whine not unlike metal sliding on metal while churning through render after render, that my big rig could do, just marginally faster.

10-23-2012, 12:09 AM
4 Core MacBook Air is rendering at about 97% of the speed of the 8 core
Holy &$#@!!
My 8-core is the same as yours - I knew it wasn't screaming fast but omg. Planning to get whatever apple offers next year. Can you elaborate on the scene? Paging can't make that huge a difference, esp. with 24gb. How long is each frame?

Can you post a scene that renders with a visible transparent polygon? I don't think I've ever had that problem, except once when I found that my transparency value was dipping below 0 into the negative.

10-24-2012, 12:13 PM
the scene relies heavily on the DPKit's edge shader node. I use it to render the lines as a bright blue. The surface is black and the whole thing has high specular with medium gloss.
I'm not raytracing anything except transparency, and on average my scene's (I've got a few of them) take about 2.5 minutes a frame.
I'm sure under different circumstances the render speeds would be wildly different.

when I get through the crunch I'll post a still.

I have activity monitor up on both machines, on the 8Core I have 16 threads in the monitor and every other one of them is idle.
on the air, there's 4 threads, and they are maxed out.

I suspect but can't prove that DPKit can't see the extra threads. I might try fussing with that later.

I think for the most part the Air's processors are really efficient, but the air has to be overcoming a 4 Gig ram limit somehow. I expect that when it pages out, its not all that bad, because of the SSD.
I'd bet money that the Fusion thing in the new iMacs, is something Apple cooked up once they noticed just how fast SOME things in an SSD are.

but to be honest my Pro is very reliable, and the speed is nothing to sneeze at. I'm very happy with it overall (I am due for a new machine next year as well) Its the best mac I've ever owned. I'm just happily surprised at what the air can do (while its plugged in)

10-24-2012, 05:28 PM
16 threads in the monitor - I forgot, I have the 2008 2.8ghz, I only get 8 threads.

But this says the Air only has 2 cores

And scores much lower than your 8 core here


10-24-2012, 06:02 PM
I'd bet money that the Fusion thing in the new iMacs, is something Apple cooked up once they noticed just how fast SOME things in an SSD are.

If the Fusion thing is a paring of an SSD with a standard HDD, I'm pretty sure it's not something that Apple cooked up since you can buy those drives now. (e.g. http://www.newegg.com/Product/Product.aspx?Item=N82E16822148837) Of course, they may have designed their own or simply trademarked a name for it. Hopefully, they'll have better quality control than Seagate. :)

Still, it's a good thing to have in their computers.

10-24-2012, 09:11 PM
its not the same thing.

Apple cooked up a version of something in the enterprise.
the data on the drives is not duplicated. both drives count towards the total storage of the "virtual drive" created when you apply fusion.
the SSD is not a mere shuttle in this instance, and you still have 1 "logical" drive.

the software was written to be aware of what is often used, and keep that on the SSD, without bothering the user.
Apple has gone to great pains to say that this is a new thing... in the desktop market (some servers will do this automatically)

raytracing shadows, drops the air down to its knees. like I said, different circumstances... anyway. the air is showing 4 threads in activity monitor, and they are pinned. I'll attach what the 8Core is showing in the activity monitor


10-24-2012, 09:46 PM
Oh I wasn't doubting what you said.

I was assuming that LW loaded everything into memory though, maybe it's doing something silly like hitting the HD all the time. Some things also render faster with a lower thread setting, maybe try 4 and 8 on the 8-core?

11-08-2012, 06:23 AM
raytracing shadows, drops the air down to its knees. like I said, different circumstances... anyway. the air is showing 4 threads in activity monitor

I've just bought an Air too - beautiful machine! But it is only dual-core, right? unless you got a new retina-display macbook pro?
Intel's current cores - for laptops and single-CPU desktops - are at least one generation ahead of their Xeon counterparts. It's kinda sad to see how the current top-end iMac crushes the top-end Mac Pro in almost all benchmarks right now (for about 1/3 of the price!).

11-08-2012, 06:55 AM
yeah, by all accounts my air is Only 2Core. For some reason, Activity viewer presents us with 4 cores. Perhaps they are virtual cores (which I thought wasn't supported on the airs)

and about the performance thing... Apple always does this. remember the black rubberized mac laptop of yore? at its debut, and for about an entire year (i think), that crazy laptop was the single fastest computer (bar none) for rendering Lightwave.

Almost every generation of Apple products leapfrogs the one before it. And unfortunately, whether there's a lack of sex appeal or desktops just take longer to design... the Apple desktops always take longer to get upped into the next generation.

the good news? Apple products tend to last longer than their PC counterparts.

11-08-2012, 07:08 AM
You must have got the i7 upgrade when you ordered it, right? That supports hyperthreading, so you'll see 4 virtual cores (running on 2 logical cores). Hyperthreading helps a bit when you're running mixed code (int, fpu, SSE) but less useful for LW and other "pure" render tasks in my experience. The i7 is about 10-20% faster than the i5 though regardless.

11-08-2012, 10:38 AM
you're right, it is an i7, didn't know that till now. but i didn't order it. I walked into an Apple store two days after they were announced and told them what I wanted.
and I just realized something: I got the i7 for free. OOPS. I just checked my credit card, and sure enough... I paid for the i5.