[SOLVED] How To Limit CPU Usage In Handbreak

system001 · 05-30-2019, 11:53 AM

i have some video files that are far larger than they need to be and i'm using handbreak to reduce their sizes. i would like to reduce the load they have on my cpu. yes i know in doing so it will take longer to convert the files, but that is fine. please any suggestions and or tutorials on doing this would be greatly appreciated. thanks

amd fx 6300 on kde neon 64 bit
nvidia 750ti on the 430 driver
kernel 5.1

hydrurga · 05-30-2019, 12:07 PM

The cpulimit application could well meet your needs.

Quote:

cpulimit is a simple program that attempts to limit the CPU usage of a process (expressed in percentage, not in CPU time).

BW-userx · 05-30-2019, 01:32 PM

On that note.

Code:

#!/bin/bash

# requires cpulimit

[[ -z $1 ]] || [[ $# -ne '2' ]] && { echo "Usage ./limitcpu command [limit percent]; exit 1 ; }

echo $1
echo $2
count=0

  pidd=$(pidof $1)
  pidd=${pidd%% *}
  
  echo "pid $pidd"
  cpulimit  -p $pidd -l $2 -z -i

while sleep 3;
do
	
   pidd=$(pidof $1) 
   pidd=${pidd%% *} 
   cpulimit  -p $pidd -l $2 -z -i
	
   if [[ $count -eq '1' ]] && [[ -z "$pidd" ]] ; then
   {
     echo "
     Ran dry...
     exiting .....
     "
     exit
    }
    else
    {
      ((count++))
    }
    fi
    [[ -n "$pidd" ]] && count=0
done

this was written with my script to resample mp3 in mind. whenever lame would stop doing one mp3 then pick up another one it catches the new pid for lame, then puts cpulimit back to work on that new pid, when mp3s where finished it's checks 1 times before exiting, to compensate for lag time between mp3's

example

Code:

$ limitcpu qbittorrent 40
qbittorrent
40
pid 25474
Process 25474 found

then you can start top to just get a look see for your own well being, and of course you can use this with your handbrake or handbrake-cli or creating a script yourself that does the same thing , or off the cli for when you are doing only one movie.

ondoho · 05-31-2019, 05:10 AM

i doubt that cpulimit would be of much help here; but surely can't hurt to try.
i think this should be a setting within handbrake; either within handbrake proper, or something passed to the transcoding software.
If ffmpeg does handbrake's transcoding, or you could switch to ffmpeg proper, here's some ideas.

hydrurga · 05-31-2019, 05:35 AM

Quote:

Originally Posted by ondoho

i doubt that cpulimit would be of much help here...

Out of interest, ondoho, why do you think that?

system001 · 05-31-2019, 05:44 AM

Quote:

Originally Posted by ondoho

i doubt that cpulimit would be of much help here; but surely can't hurt to try.
i think this should be a setting within handbrake; either within handbrake proper, or something passed to the transcoding software.
If ffmpeg does handbrake's transcoding, or you could switch to ffmpeg proper, here's some ideas.

thanks i'll have a look through some of those. much rather do that than write out a script.

berndbausch · 05-31-2019, 06:42 AM

Quote:

Originally Posted by system001

i have some video files that are far larger than they need to be and i'm using handbreak to reduce their sizes. i would like to reduce the load they have on my cpu. yes i know in doing so it will take longer to convert the files, but that is fine. please any suggestions and or tutorials on doing this would be greatly appreciated.

The traditional method is nice. It does not guarantee a CPU percentage, but increases the probability that the CPU is relinquished to non-nice processes when they want it.

Code:

$ nice -n 19 handbrake [handbrake options and arguments]

EDIT: Also renice to change the nice value of a running process.

GazL · 05-31-2019, 07:14 AM

I have this alias in my bashrc
alias nicesh='chrt -i 0 ionice -c 3 ${SHELL:-/bin/sh}'

Anything that runs or is started from within that nicesh will then run with the lowest possible priority for both cpu and I/O.

nice -n 19 isn't as useful as it once was on linux thanks to the introduction of control-groups.

jmgibson1981 · 05-31-2019, 11:39 AM

Just out of curiosity why would you want this? Is it to have more power to use the computer while encoding? Or because you think it will prevent so called wear and tear on the cpu? If the latter then you shouldn't worry about it.

Cpu's don't exactly wear out, at least not in the common sense. You won't be shortening the life of the chip by running full blast, at least not in any measurable sense. Overclocking however is a good way to blow a chip if you don't know what you are doing and don't keep it cool.

RickDeckard · 05-31-2019, 12:00 PM

Another method to reduce the stress on your CPU would be using the cpufreq-* utilities if they're available on your distribution, with a governor like "powersave."

ondoho · 05-31-2019, 12:06 PM

Quote:

Originally Posted by hydrurga

Out of interest, ondoho, why do you think that?

it's a kludge that mostly just "Limit cpu usage of a process in percentage. Actually sends SIGSTOP/SIGCONT POSIX signals to processes".
I'm not sure it'll work at all with a GUI program. Maybe it'll just limit the GUI. Surely handbrake outsources the transcoding. It would be much better to tell that process (hopefully ffmpeg) directly (via command options) to restrict itself.
And even if cpulimit can be applied, I suspect that it carries significant overhead.
But as I said, can't hurt to try.

Shadow_7 · 05-31-2019, 12:16 PM

Well if you have cooling issues, limiting how much heat you generate can help prolong your broken hardware. I ran a laptop without a working fan for over a year by only using it to look at game guides while I gamed on the other not-broken computer.

I also live in a warm region so having my computer output less heat lets the A/C turn off once in a blue moon. Other quirks like putting an I/O intensive thing on it's own storage device, so other users don't feel the pinch.

Mostly I use nice on browsers so I can kill the browsers when they misbehave. Versus waiting seconds or minutes for HID interfaces to move far enough to express my intent. Without holding a power button for seconds to kill everything.

In the case of the previous fanless, but not by design computer, it did eventually heat up enough to make the USB unstable. Which it was booting off of, so end of life at that point.

There's cpufreq and other tools to have your CPU run slower than it's max. Not exactly a per process method. But one way to not pop a fuse if you have more computers than you should on one circuit. Or otherwise live in 1970s era housing not designed for our modern electronics.

GazL · 05-31-2019, 03:11 PM

I won't speak to the OP's intentions, but the reason I use sched_idle is to maintain a responsive interactive system/desktop while big compile jobs are running in the background. sched_idle or nice won't do anything to help manage cpu thermal output; as others have mentioned, you'll need to look towards cpu frequency management if that is your concern.

system001 · 05-31-2019, 03:19 PM

it certainly didn't take peeps to get off topic and start useless speculation on why i want to limit handbreak's cpu usage. that said i only had about 40 files that needed to be reduced so decided to just let handbreak use what it wanted. thanks for the input and suggestions though.

ondoho · 06-01-2019, 12:13 AM

I did (and still do) have a use case for cpulimit - it's a script that generates a desktop background every few minutes or so. If I don't limit it, the fans spin up every time, and that's simply disturbing to me. setting nice to the lowest value does NOT help with that.
so i use cpulimit to keep it from happening. however, i don't run the whole script with cpulimit, just the crucial command.