POV-Ray : Newsgroups : povray.newusers : Problems with large RAM installed : Re: Problems with large RAM installed Server Time
10 Dec 2023 11:46:08 EST (-0500)
  Re: Problems with large RAM installed  
From: Mirfaelltkeinerein
Date: 10 Feb 2020 14:15:01
Message: <web.5e41aade187cae06ee75e2ca0@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:
> On 2/10/20 10:50 AM, Mirfaelltkeinerein wrote:
> > "Mirfaelltkeinerein" <nomail@nomail> wrote:
> >> "Mirfaelltkeinerein" <nomail@nomail> wrote:
> >>> Hi all,
> >>>
> Are you using POV-Ray v3.7 or the in progress v3.8 master branch? If the
> former, it might be worth trying the latter as Christoph fixed quite a
> few (all ?) fixed memory allocations which might cause stack issues and
> hence odd problems/crashes(1). I'm not a window user, but there are
> pre-compiled windows binaries for v3.8 releases. See:
> https://github.com/POV-Ray/povray/releases

I'm using 3.7 and I didn't know of 3.8. I should try it out.

> ---
> Aside: There was a recent TechSpot review of a dual socket 3990X system
> including POV-Ray where they mention AMD providing a POV-Ray patch to
> support all the cores/threads instead of 'just' 64. There is a pull
> request in:
> https://github.com/POV-Ray/povray/pull/387
> which I assume is this AMD fix, but I don't know for certain. Perhaps
> someone on the core team got email saying for sure? In any case if you
> are up to merging and compiling that pull request, it would be
> interesting to see if you can then use all your cores and threads - even
> if just on the smaller render.

Thank you very much, I'll try it out.

> When you say the render cannot be stopped and runs until the end, do you
> mean it continues with 1 thread AND still produces a good result?
> Surprised if this is what's happening, but maybe?

Yes, the render goes on and seemingly with the appropriate amount of render
threads (it looks like that, as a number of tiles become finished at different
times). But you can push the 'Stop' button in the GUI or press Alt-G, nothing
happens, the rendering continues. And Task manager says that just one core is
busy. The 'PPS' number supports that reading.

> Why do you think your memory upgrade might be playing a part in what you
> now see? Were you able to render the 'problem' dimensions with the
> smaller amount of memory previously?

Yes, I upgraded the memory, rebooted and the very first test was POVRay with the
saved settings I used before for a rendering. And I used the setting before many
many times without problems. When I reduced the image size to halve of that
amount (2000x1000), rendering (in PPS) was much faster and also all 24 cores/48
threads were used.
Then I increased image size step by step.

> In whatever version of POV-Ray you are using have you tried the problem
> render with fewer threads using say +wt24 or something? Lastly, might
> guess with a machine this powerful, it might be running other things? If
> so, might these be causing what you see?

After the reboot nothing else was running, except the operating system with all
its stuff.

But what I found out now is that when I run Comsol in parallel doing some heavy
calculations, POVRay also behaves as expected. Slightly slower as if it were
alone, but much faster as with the problem. I'm confused...

> Bill P.
> (1) - A part of this work was tangled in moving off boost threads to
> C++11 built in threads. The boost threads implementation could be
> tangled in your problem too I guess if you are not using a recent 3.8
> release.

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