POV-Ray : Newsgroups : povray.general : Does POV not use Intel's "performance" cores? : Re: Does POV not use Intel's "performance" cores? Server Time
26 Sep 2022 06:20:19 EDT (-0400)
  Re: Does POV not use Intel's "performance" cores?  
From: Scott
Date: 28 Jul 2022 08:15:00
Message: <web.62e27d4fac2f40e419ad958a2fdca92@news.povray.org>
"Scott" <spa### [at] spamcom> wrote:
> Thorsten <tho### [at] trfde> wrote:
> > Hello,
> >
> > it is the operating system, not the application that decides which cores
> > get used by which thread. You may want to check the energy efficiency
> > settings of your operating system as they might assign all threads to
> > just 8 of the cores for some reason.
> OK I found the issue.
> Render Priority in POV menu of "Normal" (the default) sets the render priority
> as "Below Normal" in task manager, which limits it to only using Efficiency
> cores.
> If I set Render Priority to "High" in POV, this corresponds to "Above Normal" in
> task manager, which makes the whole system quite unresponsive, but does use all
> cores.
> The solution is to keep priority as "Normal" in POV, then immediately after
> starting the render, go into Task Manager and change the priority of the POV
> process to Normal. This then makes it use all logical cores.
> A bit inconvenient, I wonder why "Normal" in POV is converted to "Below Normal"
> in task manager?

According to POV source code (windows/pvengine.cpp line 1029) this is the
defined behaviour, the default "Normal" priority within POV in fact sets the
Windows process priority to BELOW_NORMAL_PRIORITY_CLASS, which in turn means
Windows treats this as a low priority task and will only schedule it on
efficiency cores, leaving the performance cores sat idle. I can compile a new
version to get around this once I get VS installed, but others may not be
capable of doing this. I assume this is going to become more of an issue once
Intel's efficiency/performance core architecture filters down to more CPUs.

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