POV-Ray : Newsgroups : povray.windows : Not using all CPU Server Time
18 Sep 2021 07:48:03 EDT (-0400)
  Not using all CPU (Message 5 to 14 of 14)  
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From: Alain Martel
Subject: Re: Not using all CPU
Date: 13 Jan 2021 12:09:35
Message: <5fff294f$1@news.povray.org>
Le 2021-01-13 à 05:55, Le_Forgeron a écrit :
> Le 12/01/2021 à 23:29, Mike Horvath a écrit :
>> 6 physical cores
>> 12 logical cores
>>
>> What is "WT"? Thanks.
>>
> 
> WT is working thread; the number of thread uses by the engine to trace.
> 
> +WT1 forces to use a single thread.
> 
> IIRC, windows is not very cooperative in its scheduler, so using all the
> cores might be dangerous.
> Also, did you check if you have any "thermal" tuning (I do not know if
> that change make it in the production version, it was done for
> space-ship usage). It might be all in the menu part.
> 

As long as you don't set the priority to high, you should set WT to the 
actual number of logical cores.
For 6 cores with 12 logical cores, you should use +wt12.
Also, by default, POV-Ray version 1.7 and later is be set to use all the 
logical cores present. At least, that's the case on my computer.

Yes, the «duty cycle» is present since version 1.6. It can be set from 
10% to 100% in 10% increments, and yes, it was implemented for use on 
the ISS.

What can make your CPU time go lower could be thermal throttling. This 
can happen if there is to much dust in the heat sink of the CPU. It 
should be cleaned at least once a year, more if you are in a dusty 
environment.

Some other possible causes would be another CPU hungry process running, 
or memory use getting to high and swapping start happening.


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From: Norbert Kern
Subject: Re: Not using all CPU
Date: 13 Jan 2021 13:55:01
Message: <web.5fff412c4dfe1d194d4aa4600@news.povray.org>
Mike Horvath <mik### [at] gmailcom> wrote:
> I just got a new PC with an i5 10400.
>
> I noticed that Povray for Windows is only using 35% of the CPU. The load
> does seem spread across multiple cores however.
>
> Why isn't Povray using more CPU?
>
> Thanks.
>
>
> Mike


Interesting - my win10 machine shows the opposite problem (since a recent
win-update I assume). Despite setting povray priority to the lowest value
possible, I have to pause any render for using Firefox or even the windows
explorer...

According to the task-manager Povray uses at least 99 % CPU power (i7-8700K - 6
cores 12 threads).

Norbert


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From: Mike Horvath
Subject: Re: Not using all CPU
Date: 13 Jan 2021 14:46:56
Message: <5fff4e30$1@news.povray.org>
Yeah, my old PC was always pegged at 100% CPU on all 4 cores.

This is frustrating because the whole reason I got such a powerful CPU 
was so that I could do more raytracing. Otherwise, I don't need such a 
good CPU.

:(


Mike



On 1/13/2021 1:51 PM, Norbert Kern wrote:
> Mike Horvath <mik### [at] gmailcom> wrote:
>> I just got a new PC with an i5 10400.
>>
>> I noticed that Povray for Windows is only using 35% of the CPU. The load
>> does seem spread across multiple cores however.
>>
>> Why isn't Povray using more CPU?
>>
>> Thanks.
>>
>>
>> Mike
> 
> 
> Interesting - my win10 machine shows the opposite problem (since a recent
> win-update I assume). Despite setting povray priority to the lowest value
> possible, I have to pause any render for using Firefox or even the windows
> explorer...
> 
> According to the task-manager Povray uses at least 99 % CPU power (i7-8700K - 6
> cores 12 threads).
> 
> Norbert
> 
> 
> 
>


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From: Mike Horvath
Subject: Re: Not using all CPU
Date: 13 Jan 2021 14:53:07
Message: <5fff4fa3$1@news.povray.org>
On 1/13/2021 12:09 PM, Alain Martel wrote:
> What can make your CPU time go lower could be thermal throttling. This 
> can happen if there is to much dust in the heat sink of the CPU. It 
> should be cleaned at least once a year, more if you are in a dusty 
> environment.

The PC is virtually brand new and I just peeked inside the case a few 
weeks ago. It is clean.





> 
> Some other possible causes would be another CPU hungry process running, 
> or memory use getting to high and swapping start happening.

The CPU is at about 40% usage (according to Task Manager) for all 
programs currently running.

Memory usage is like 60%.


Mike


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From: Le Forgeron
Subject: Re: Not using all CPU
Date: 13 Jan 2021 15:25:03
Message: <5fff571f$1@news.povray.org>
Le 13/01/2021 à 20:53, Mike Horvath a écrit :
> On 1/13/2021 12:09 PM, Alain Martel wrote:
>> What can make your CPU time go lower could be thermal throttling. This
>> can happen if there is to much dust in the heat sink of the CPU. It
>> should be cleaned at least once a year, more if you are in a dusty
>> environment.
> 
> The PC is virtually brand new and I just peeked inside the case a few
> weeks ago. It is clean.
> 
> 

Did the render take enough time ?
What is the size of the image, compared to the blocksize (+BS setting,
default is 32, IIRC)
So a picture of 256 x 256 is made of only 64 blocks, and they are not
evenly distributed, at the end it is always some late single block which
is blocking every one else.
64 blocks to render on a wallpaper, 12 cores remove 12 blocks,
52 blocks to render on a wallpaper, 12 cores remove 12 blocks,
40 blocks to render on a wallpaper, 11 cores remove 11 blocks, one core
is late.
29 blocks to render on a wallpaper, 10 cores remove 10 blocks, two cores
are late.
19 blocks to render on a wallpaper, 12 cores remove 12 blocks,
7 blocks to render on a wallpaper, 5 cores are idle, 4 cores remove 4
blocks,
3 blocks to render on a wallpaper...


Did you try to run the benchmark ?


How is the temperature censor of the CPU as the render progresses ?

Is it a laptop in economy mode ?

Is there some energy management in use ?

i5 10400 is reported as 6 cores, 12 threads, base frequency 2.9, max
turbo at 4.3 (but turbo is out of question with povray, it is a mode
when only a single core is used)

TDP is 65 W, I do not know how much that is for a 14nm. (hence my
question about temperature above)

Also, povray enjoy floating point operation everywhere, so it might
trigger bottleneck on the execution of threads (2) over single true
core(1). I do not know the cache size of the CPU per core either.

The graphic chip is also embedded, I do not know if it can have an impact.


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From: Mike Horvath
Subject: Re: Not using all CPU
Date: 13 Jan 2021 16:09:16
Message: <5fff617c@news.povray.org>
On 1/13/2021 3:25 PM, Le_Forgeron wrote:
> Did the render take enough time ?
> What is the size of the image, compared to the blocksize (+BS setting,
> default is 32, IIRC)

Width=1920
Height=1440
Preview_Start_Size=16
Preview_End_Size=16
Render_Block_Size=16
Render_Pattern=3


> Did you try to run the benchmark ?
> 

No. I will do this when the current render is completed. (One or two days?)




> How is the temperature censor of the CPU as the render progresses ?
> 

I have been unable to get a temperature reading off the CPU using 
several programs. The readings for the GPU and even the HDD show up, but 
not the CPU. Weird. It's a Dell so maybe there is proprietary software? 
Dunno.




> Is it a laptop in economy mode ?
> 

Desktop.




> Is there some energy management in use ?
> 

I have no idea.




> i5 10400 is reported as 6 cores, 12 threads, base frequency 2.9, max
> turbo at 4.3 (but turbo is out of question with povray, it is a mode
> when only a single core is used)
> 
> TDP is 65 W, I do not know how much that is for a 14nm. (hence my
> question about temperature above)
> 
> Also, povray enjoy floating point operation everywhere, so it might
> trigger bottleneck on the execution of threads (2) over single true
> core(1). I do not know the cache size of the CPU per core either.
> 






> The graphic chip is also embedded, I do not know if it can have an impact.
> 

I am using an external nVidia card.



Thanks for the help.

Mike


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From: Thomas de Groot
Subject: Re: Not using all CPU
Date: 14 Jan 2021 02:48:41
Message: <5ffff759$1@news.povray.org>
Op 13/01/2021 om 20:46 schreef Mike Horvath:
> Yeah, my old PC was always pegged at 100% CPU on all 4 cores.
> 
> This is frustrating because the whole reason I got such a powerful CPU 
> was so that I could do more raytracing. Otherwise, I don't need such a 
> good CPU.
> 
> :(
>


For a render, I typically set +WT at 'maximum logical processors minus 
2'. As I have here 6 cores and thus 12 logical processors, I set +WT10. 
Thus I am always able to do something else besides the render.

Possibly, your WT is set low by default. Changing WT and watching the 
Task Manager you will see CPU utilisation change. I noticed that when 
CPU utilisation gets close to 90+% no render time is really gained, so 
it seems always better to set a lower WT to keep it under the 100%

-- 
Thomas


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From: Alain Martel
Subject: Re: Not using all CPU
Date: 14 Jan 2021 12:13:04
Message: <60007ba0$1@news.povray.org>
Le 2021-01-14 à 02:48, Thomas de Groot a écrit :
> Op 13/01/2021 om 20:46 schreef Mike Horvath:
>> Yeah, my old PC was always pegged at 100% CPU on all 4 cores.
>>
>> This is frustrating because the whole reason I got such a powerful CPU 
>> was so that I could do more raytracing. Otherwise, I don't need such a 
>> good CPU.
>>
>> :(
>>
> 
> 
> For a render, I typically set +WT at 'maximum logical processors minus 
> 2'. As I have here 6 cores and thus 12 logical processors, I set +WT10. 
> Thus I am always able to do something else besides the render.
> 
> Possibly, your WT is set low by default. Changing WT and watching the 
> Task Manager you will see CPU utilisation change. I noticed that when 
> CPU utilisation gets close to 90+% no render time is really gained, so 
> it seems always better to set a lower WT to keep it under the 100%
> 

Leaving the rendering priority to normal and using all logical cores all 
the time and I experience no slowing down for the other processes.
IF I set the rendering priority to high, then I do need to reserve at 
least one core for other tasks.

The normal priority set the rendering effective priority to «lower than 
normal» while the high priority do set the effective priority to high.


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From: Mike Horvath
Subject: Re: Not using all CPU
Date: 15 Jan 2021 01:00:59
Message: <60012f9b$1@news.povray.org>
This worked, thank you.


Mike




On 1/14/2021 2:48 AM, Thomas de Groot wrote:
> Op 13/01/2021 om 20:46 schreef Mike Horvath:
>> Yeah, my old PC was always pegged at 100% CPU on all 4 cores.
>>
>> This is frustrating because the whole reason I got such a powerful CPU 
>> was so that I could do more raytracing. Otherwise, I don't need such a 
>> good CPU.
>>
>> :(
>>
> 
> 
> For a render, I typically set +WT at 'maximum logical processors minus 
> 2'. As I have here 6 cores and thus 12 logical processors, I set +WT10. 
> Thus I am always able to do something else besides the render.
> 
> Possibly, your WT is set low by default. Changing WT and watching the 
> Task Manager you will see CPU utilisation change. I noticed that when 
> CPU utilisation gets close to 90+% no render time is really gained, so 
> it seems always better to set a lower WT to keep it under the 100%
>


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From: Thomas de Groot
Subject: Re: Not using all CPU
Date: 15 Jan 2021 02:45:30
Message: <6001481a$1@news.povray.org>
Op 14/01/2021 om 18:13 schreef Alain Martel:
> Leaving the rendering priority to normal and using all logical cores all 
> the time and I experience no slowing down for the other processes.
> IF I set the rendering priority to high, then I do need to reserve at 
> least one core for other tasks.
> 
> The normal priority set the rendering effective priority to «lower than 
> normal» while the high priority do set the effective priority to high.
> 

Ah, ok. I still have ingrained habits from older times it seems ;-)

However, I do prefer to set a bit lower number of WT's on my laptop 
because of the insane noise of the fans otherwise when rendering complex 
scenes. Maybe I should use Duty Cycle instead... It is something I have 
not thought about really seriously.

-- 
Thomas


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