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Fast Computer – Slow Rendering!
When i RAM preview i get a reasonable render speed.
When i output from the render que not only does it render extremely slowly but it completely hogs the entire machine to the point that EVERYthing lags as if i’m rendering on a single core pc with low ram. i move the mouse and i have to wait 10sec for it to respond, i cmnd+tab and i have to wait even longer. it also grows increasingly slow as the output continues.
This is a big problem because i must move very quickly at my job
I running on a Mac Pro (2x Intel Quad Core) and Leopard.
i have had a lot of experience with after effects over the course of 4 years and i am an advanced user
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11 Replies
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this happens to me regardless of what footage i use, even if i create something completely in solids, adj layers, etc.. i get the same result
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..also i seems to be linked to the multiprocessing feature
i notice that it doesn’t give me as many problems when i turn up the ram cache size – i have used decreased ram cache size (allowing for more processor cores to be used) to get more speed on other computers successfully. Specifically, another Mac Pro (8core 3gb) … in fact this one has 4gb but is having more problems
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with only 4gb of ram, you’re pretty short on ram if you want to use all the cores… i’d recommend scaling back to 4 cores at the most… this will give 1gb of ram to each for the 4 cores. if you are working in hd, you might even try to scale back to just 2 cores so you can have 2gb per core.
your ram cache feeds the processors the data to process. if the processors can’t get enough data fast enough, then you get a bottleneck and decrease performance. in cases like that, giving more ram to fewer cores should actually increase performance.
another thing that can negatively effect performance is enabling disk cache if you only have one drive, or are using multiple drives on the internal drive bus. the drives supply data to the ram, so if the drive bus is getting saturated, then it will become a bottleneck. so, generally, if you don’t have an external drive/drive array for your media and renders, disable disk caching. if you do have and external media drive, then set disk caching to use the internal drive and use the external for all media and renders, this will split the data path onto two separate drive buses and should increase performance, or at least decrease the chance of either bus getting saturated and causing a problem.
Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW -
I wouldn’t recommend using 4 cores with 4GB of RAM. The background processes used for multiprocessing will starve.
With just 4 GB of RAM, I would set Multiprocessing to leave 6 CPUs free, and use the remaining 2 cores. And you definitely want more RAM. As Kevin said, at least 2 GB per core. So, while 16 GB of RAM would be recommended for an octo-core, you could get for example an extra 4 GB an use 4 cores.Adolfo Rozenfeld · Adobe
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Adolfo’s spot on here. Without upgrading the ram on your machine, you can also improve your multitasking performance by turning multiprocessing OFF in the “Memory and Multiprocessing” section of the preferences AND bumping up the value for “RAM to leave for other applications”
By default, we assume you want AE to use all of your machines resources. By setting your “RAM to leave for other applications” to 2GB, you should have extra processors and ram for other applications.
I highly recommend bumping up the RAM on your Macs though. An 8-core machine with 4GB ram will likely underperform a 4-core machine with 8GB ram.
Dan Ramirez
After Effects
QA Engineer -
Does this apply to all versions? I just got CS4 and am looking to tweak it to maximize my efficiency. Any other good tips?
Stephen Rutherford
Graphics Producer: Gale Force Media, CanesVision & Wolfpack TV
stephenr@carolinahurricanes.comCAROLINA HURRICANES: 2006 STANLEY CUP CHAMPIONS!
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This applies to CS4 mostly.
CS3 introduced this kind of multiprocessing, but didn’t expose a direct way to specify the number of cores/processors to leave free. So, if you didn’t have enough memory to use all of them, it would just shut down.Adolfo Rozenfeld · Adobe
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There is a way in CS3 to regulate the number of processors used: there is a free script called “Throttle” that will let you do that.
It even lets you render in the background.
To improve your rendering you might want to have 3 Mb per CPU.
Good luck!
Kim
A computer once beat me at chess, but it was no match for me at kick boxing.
–Emo Philips
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Ok seems pretty clear now that I need a computer with 16gb and 8cores – i can feel the difference immediately when i bump up the amount of ram to each core, it’s quite satisfying actually, like eating fancy expensive chocolate.. mmm… thanks 🙂
Dead the Fed
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Hi there all,
I’m not sure if I should start a new thread but since this a continuation of the original question I’ll post here first as I think anyone reading this will be interested in any responses.
I’m running a new machine (Octocore with 16Gb memory) with CS4. I’ve played around with the multiprocessor settings and have found that it’s a matter of trial and error (or just trial really) to get the best settings. I can concur with everything said above with regards to more memory per processor, however I’ve found my render times change dramatically between dedicating all the processors and all the memory, or half the processors and all the memory, to just turning it off all together (which I believe gives AFX 16 processors but only 3.5GBs of ram). Depending on how the project is set up each setup can be the fastest way to render a project. As a footnote to this, the more instances you run the more overall system overheads you will see (bus and bandwidth bottlenecks/saturation et al as mentioned above). It sounds logical but even if you had 32Gbs of memory and a blindingly fast raid array, running 16 instances of AFX would not be as fast as running only eight instances I’m sure. I could be wrong? Can anyone vouch either way?
My question is this, when you turn on multiprocessor rendering it will start a new instance of AFX for every processor you assign it and it will then dedicate the designated amount of memory to each process. However, is it possible to (maybe using a script?) tell AFX to run only two instances but assign say three or four processors (as opposed to the one) and 7-7.5Gbs of ram to each instance?
Before anyone asks why I would want to do this let me explain the method to my madness. My theory is that since each instance of AFX is accessing the HDD for the information for the next frame to render (either an image or frame from a movie, either way it’s probably in the same place as the footage for the last frame). The HDD won’t be able to keep up with the amount of accesses asked of it (being the slowest part of any modern computer (and it can’t, I’ve tested this with my 10k SATA drives (I’ll get a raid0 or 5 one day)). So running fewer instances would mean mean that the HDD wouldn’t be taxed as much. So two (or three) instances of AFX running as opposed to six or eight would be better for HDD access times. This way I would also be able to make use of all the processing power my system has available.
Any thoughts? Sorry for the long post.
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