Is MeshCAM running out of memory? How much is needed?

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Is MeshCAM running out of memory? How much is needed?

Postby cnczane » Sat Mar 11, 2017 7:37 pm

Is there a way to cipher how much RAM a G-code rendering for a model is going to need?

Ordinarily I cut my wooden-map models with a 1/2" rougher and a 1/8" round finisher. Only I got into one region where the 1/8" is just too fat, so I decided to jump all the way down to a 1mm round.

The model volume fits within 24x12x0.5. The cutters are: rough, 1/2"Diam 0.2"sd 0.4"so, finish: 1mmDiam 2mm sd 0.1mm so

What is the calculation for how much RAM is required? :^) I know, it's facetious. Still, I am eyeing some Big projects and would be comforted to know that MeshCAM will still work for them if I just add RAM (currently 8GB, planning 32GB).

I'm running MC5 (mostly, MC6 introduced display issues) in wine on Linux, so there is memory overhead, but I can monitor MC's memory usage with 'pidstat' (part of the 'sysstat' pkg) and see that the %MEM usage ramp up and up. And I can see "major page faults per second": those which require reloading a memory page from disk. It seems to grow and grow and grow and crash.

Quoting Wikipedia on "Page Fault" https://en.wikipedia.org/wiki/Page_fault:
An average hard disk drive has an average rotational latency of 3 ms, a seek time of 5 ms, and a transfer time of 0.05 ms/page. Therefore, the total time for paging is near 8 ms (= 8,000 μs). If the memory access time is 0.2 μs, then the page fault would make the operation about 40,000 times slower.


That's what it feels like: about 40,000 times slower... :^)
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Re: Is MeshCAM running out of memory? How much is needed?

Postby Gerry » Mon Mar 13, 2017 5:58 pm

You're going to need a 64bit version of MeshCAM to take advantage of more memory. I think that I got Meshcam to use 6-7Gigs of ram while doing a test for ram usage.
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Re: Is MeshCAM running out of memory? How much is needed?

Postby cnczane » Sun Mar 19, 2017 8:44 pm

Thanks, Gerry.

I am running the 64-bit version and have 8GB of RAM. I am on-schedule for getting a new system with 32GB, but what I was experiencing looked like the memory requirements were growing without bound (which means I ought to try to get 64GB. ;^ )
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