Hardware performance for Photoshop (A large project)

" I tried it with Mac Pro 2013 and iMac Pro with 64GB of RAM but they were extremly slow to handle a such file. The memory was maxed out. Apple Silicon Mac with unified memory should be much faster " 

I'm sorry, I don't follow that at all. If the memory is maxed out, then the DISK (SSD) is used instead.

The unified memory makes zero difference to this - except to mean you have less. The disk will still be needed.

Unified memory means there is less time moving info between the GPU and CPU. It doesn't give you more memory, or help you out when you need to use disk instead.

https://www.howtogeek.com/701804/how-unified-memory-speeds-up-apples-m1-arm-macs/

First of all, you don't need 300 ppi for large prints. That's probably the most persistent myth in all of digital imaging. It has to do with viewing distance. 300 ppi is for books and magazines to be seen from less than arm's length. I've made wall-sized banners at 25 ppi, and they're razor sharp for the situation.

That said, though, for files of this size it's not about RAM. Forget about having "enough RAM", you never do no matter how much you have.

This is about the scratch disk. That's where the heavy lifting is! That's the bottleneck. You need a fast NVMe drive with at least 500 GB free space - but in this situation I'd go for a full TB.

These file sizes will be well handled by Photoshop as long as you have sufficient hardware resources, and in this case, that means bandwidth. They are well handled by x86 as it is, no problems that need solving.

What is end product of files this huge?

The way memory and all those CPU and GPU cores interact in the newest Apple Silicon Macs is so different than traditional x86-based systems that it’s hard to say for sure what the best configuration is until we see more people doing tests with large files.

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@aiur4 wrote:

Each project file size is between 10~30GB. Yes, it is huge. I tried it with Mac Pro 2013 and iMac Pro with 64GB of RAM but they were extremly slow to handle a such file. The memory was maxed out.

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How was the memory maxed out? What was Memory Pressure showing in Activity Monitor; was it green, orange, or red? If it was orange or red, there was definitely not enough RAM; but if it was green, RAM was OK and the problem was somewhere else.

For CPU and GPU, you can see what Activity Monitor reports by choosing Window > CPU History and Window > GPU History, which are graphs over time. If a graph is always full, that is a bottleneck. If a graph is usually empty, either that is not a bottleneck or Photoshop isn't taking advantage of it.

You can test a large project on your M1 and see which of the areas are under the most strain — memory, GPU, or CPU. That could provide a clue as to how to configure a more powerful M1 for the same project. For example, if memory and CPU were not busy but GPU is, then that would suggest that a more powerful GPU might help.

But the answer might still not be straightforward, because the various features of Photoshop are not optimized evenly. Very generally, RAM is used to hold layers for editing, CPU is used to run calculations, and GPU accelerates some features, including view changes like panning and zooming. So it also depends on which features you use on the large project, and whether they match up well with the areas of Photoshop that are optimized for CPU cores and GPU acceleration.

Each project file size is between 10~30GB. The canvas size is 66X44 at 300 PPI.

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Unfortunately, 66 x 44 means nothing without the parameters  -- pixels, inches, centimeters, columns...

If this is for print, do you really need 300 ppi?  I ask because a sign for a building is typically only 150 ppi or less. 

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@aiur4 wrote on 18 October:

Tagging @Conrad_C , who may be best able to answer your question.

Jane