Using the Mac 8-core to best advantage

#1

I have the MacPro 8-core with 9 gigs of RAM and I’d like to use it with EI as efficiently as possible and am hoping you mavens can give me the benefit of your experience. Specifically:

  1. I’m assuming that the main advantage of that extra RAM with respect to EIAS is the ability to have the memory available to multiple cameras when running Renderama under OSX, is this correct? In other words, I’m assuming EIAS is still a 32-bit app and cannot itself access more than the 4 gig limit but the extra RAM would be available when setting up a camera per processor?

  2. I do have boot partitions for both XP-32 and XP-64 but have only been running EIAS on the OSX side of the coin. I’ve assumed that there was no point installing EI on the 64-bit partition (and I’m not even sure if it will run as a 32-bit app there). Is it possible to use all my RAM under a windows boot with EIAS and its cameras in some way?

  3. I’ve read in other threads that there are diminishing returns with respect to I/O and processing overhead as you add more cameras to Renderama. What do people find is the best way to get the most out of an 8-core with EIAS? Do those of you with these machines typically use 8 cameras when you go to final renders? Is there a rule of thumb as to when you find it worth the trouble to do so?

Thanks

#2

  1. That’s right. Given that one can launch up to eight slave Camera apps in such a beastie, optimally one would have enough RAM to divide among the Cameras so that they won’t choke when rendering a biggie project (plus some breathing space left for OS X, around a gig or a gig and a half I’d say). Your 9 GBs suggest trying eight slave cameras with a GB RAM each and seeing what happens.

  2. Win64 wouldn’t provide any advantage here, I believe. As you said, EIAS’ apps are 32-bit only, so

  3. I remember Ian or somebody else saying it is a good idea to spread the slave cameras among several hard disks, so perhaps it would be a good idea to fill that Mac Pro with a few cheap HDs, at the very least. I wonder if someone has done any benchmark about it.

#3

i filled up with 4 HD’s…

it -seems- faster, i haven’t done any benchmarks yet though…

#4

When I first got my 8-core I tested all the possibilities - from 1 to 16 slaves with various ram allocations. I made some nice graphs, which I will try to dig out. The result was the obvious one that 8 slaves with the ram evenly split (1GB left free) was fastest.

DaveW

#5

My experience and testing shows that no single setup is “fastest”. Every project will be different.

I have had some striped renderings render faster with 16 strips vs. just 8 (on 8 core system). Some portions of an image will be more processor intensive. It depends on what % of your rendering is “slow” and how efficiently these slow areas are distributed among multiple processors. Also note that if you are running into RAM limitaitons with camera (rendering very high res GI scenes for example) you can divide your image into many many strips (say up to 80) and this can help reduce the RAM needed for each strip.

I also have 8 slaves distributed on 4 drives. For some projects this makes no difference, for others it is absolutely necessary.

Generally more slaves are better. I tend to run 6 or 7 so i can continue working using the 1 or 2 processors that are “free”, But using all 8 is certainly fastest.

If your are striping a still image you may see only a little performance improvement, or you may see a lot (anywhere from 50% faster to 300% faster).

When striping an image the rule of thumb is 1 strip per slave, but in some cases where a render has a small but very processor intensive area, more strips may be slightly faster (20% or so).

I would stay away from striping if you are animating. Rendering 1 frame per slave simultaneously should be the most efficient setup. The new Mac Pro is about 16x faster when rendering animation than my old G5 using a single Camera.

Good luck :slight_smile:
Dave

#6

my 8 core is the newest version. From what I understand, all the "wider busses and pipelines and faster memory ALL contribute to much better renderama performance.
I personally love the performance. I have 16 gigs of ram. Everything just loads faster
on the newer box. I soon will have a second 8 core that I definately will put to use.
Even if there is a decline in performance “per processor” getting 12x the performance over 8 is still a great thing. I do not notice a speed increase with rama on multiple drives.

#7

Hi Scott,
I agree about the new Mac Pro being faster overall- not just CPU- but everything. Rama seems to really like the new hardware.

Just a note about using multiple drives for speed- It all has to do with what’s in your project, and the size of the cache page file. This is Camera’s temp file. Doing something that caches a lot of data (like using an illuminator that generates lots of phong shadows) will generate very large files, easily 1GB or more.

Now, if 8 cameras each have a 1 GB (or larger) file, You would be trying to read/write 8 different 1GB files from the hard drive simultaneously. Each Camera’s speed will be limited to the throughput bottleneck of the Hard drive.

That said- this slowdown is possible, but not guaranteed. It all has to do with the specific project you are working on, and what rendering features you are using. If your typical workflow does not use certain features that generate large cache page files, then no problem.

But a few extra cheap HD’s only add a couple hundred to the overall system cost, and will pay for themselves with just 1 job that does see this kind of throughput problem :wink:

Good luck all.

Dave

#8

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.