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There's an interesting issue with certain Linux CPU governors that will actually bring down performance in Vulkan games. You might not need this, depending on what CPU governor you have installed.

You might end up seeing jerking or micro-stutter, far more than you would in OpenGL games. The issue is that when using OpenGL in games, you're generally taxing a single core of your CPU due to less multi-threading. With Vulkan spreading the load more, your CPU isn't being used so much.

The Linux CPU governor takes that as an opportunity to bring down your CPU performance, as right now it's not the smartest bulb in the tanning bed.

Here's what a Croteam developer said about the issue:

QuotePowersave governor is an awful choice for playing games. It may quite be the case that it's not happening for OpenGL especially because GL runs slower.
When the game is running fast enough that CPU has to wait on the GPU, the governor sees that as an opportunity to downclock the CPU, or put cores to sleep. The jerking is a result of the CPU throttling up and down very quickly.
In general, CPU governors on Linux are much, much dumber than the Windows one. (It seems that Windows overrides the throttling for all 3D apps, or similar.)
That's why we have this warning in the log. Switch over to Performance governor, at least while playing.

So a tip for now when playing Vulkan games on Linux: Set your CPU to high performance mode, you can do it like so in terminal ("performance" is just an example, see more here):
echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
A higher performance mode will generally result in higher power consumption too.

Then to set it back to normal. You don't need to use "powersave" see more options here, as it's just an example. According to the Arch Wiki you likely want "ondemand" for AMD:
echo powersave | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

You can find out what performance mode you're in right now by running this in terminal:
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
My default on the Intel i7 5960x is powersave, for example.

Hopefully this issue will be fixed as more games come over to Vulkan. It would be nice if developers didn't need to code around issues like this on Linux.

Article taken from GamingOnLinux.com.
Tags: Editorial, HOWTO
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Cybolic 23 Mar, 2017
Quoting: M@yeulC
Quoting: Cybolic
Quoting: HailToTheGrail
Quoting: CybolicI wish there was a way to not have to put in my password on every change, maybe someone knows how to work around that?

You could give setuid a try. Make a shell script as root, and then: chmod u+s script.sh
You should be able to run it as a user with it's owner rights, which are root.

No go on my Arch system. I've also tried editing the sudoers config file with visudo and using sudo instead, but that still asks for a password :/

Are you sure it is owned by root?
chown root script.sh

A plasmoid to change the CPU governor doesn't seem a bad idea, I might look into that.
Yup: [cybolic:~] $ cat .local/bin/set_cpu_scheduler.sh 
#!/usr/bin/bash
exec cpupower frequency-set -rg "$1" 
[cybolic:~] $ sudo chown root .local/bin/set_cpu_scheduler.sh 
[cybolic:~] $ sudo chmod u+s .local/bin/set_cpu_scheduler.sh 
[cybolic:~] $ ls .local/bin/set_cpu_scheduler.sh -l
-rwsr-xr-x 1 root root 54 Mar 23 18:11 .local/bin/set_cpu_scheduler.sh
[cybolic:~] $ set_cpu_scheduler.sh performance
Subcommand frequency-set needs root privileges



Last edited by Cybolic on 23 March 2017 at 4:16 pm UTC
kibbles 23 Mar, 2017
From my quest to get my "gaming" laptop (iow a laptop with nvidia gpu) to stop gobbling the battery so fast I read into this quite a bit.

If your using a modern intel cpu use pstate instead of the generic governors. It is demonstratively better.

You can also crank up your gpu
# set to performance
nvidia-settings -a "[gpu:0]/GPUPowerMizerMode=1"
# set to adaptive
nvidia-settings -a "[gpu:0]/GPUPowerMizerMode=0"

And cranking up the priority of the game helps, but not too high as it can starve other stuff and you get a different kind of lag.
Kohrias 23 Mar, 2017
Thanks a lot for bringing this up, Liam! I hope there will be some solutions (in whichever software/layer) to address this automatically in the future. Until then this is really something to take into account when gaming on Linux.
marcus 23 Mar, 2017
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Concerning setuid on Scripts. This should *not* work on any recent Linux system, as it provides an even larger possible security vulnerability than setuid is to begin with. For details see here:

http://www.faqs.org/faqs/unix-faq/faq/part4/section-7.html

Regarding the frequency governers for Intel CPUs:

These governors are *not* comparable to the regular pstate driver for Linux (e.g. used on older Intel Cores and AMD Cores). Intel implements its own policies in the driver that are independent of the cpufreq policies. Thus cpufreq policies will *not* work as expected. Details can be found here:

https://www.kernel.org/doc/Documentation/cpu-freq/intel-pstate.txt

This driver especially does *not* honor additional cpufreq settings apart from max_freq / min_freq.
FredO 23 Mar, 2017
I did some more testing, and for my system I get up to 50% more FPS! This is something SIGNIFICANT especially if you have a bunch of cores to load up. OnDemand was my system default:

Total War:Attila:
OnDemand: 22.7 Ave FPS, Performance: 33.9 Ave FPS
Total War:Warhammer:
OnDemand: 57.7 Ave FPS, Performance: 74.0 Ave FPS
CoH2:
OnDemand: 27.8 Ave FPS, Performance: 49.2 Ave FPS
Dirt Rally:
OnDemand: 51.6 Ave FPS, Performance: 101.3 Ave FPS
Deus Ex: Mankind Divided:
OnDemand: 40.6 Ave FPS, Performance: 50.5 Ave FPS

Edit: Better layout.


Last edited by FredO on 23 March 2017 at 6:27 pm UTC
qgnox 23 Mar, 2017
[quote=buenaventura]I [quote=Eike]
Quoting: buenaventurashedutil <--- INTRUIGING, what is this? I google and it seems like some newfangled stuff? I wonder if that will be even better than Performance!

Still, why does it only go up to 2,00ghz? Says right on the sticker on my lappy "up to 2.4 ghz", bullshiet :P
If you want to use the 2.4GHz with schedutil governor add intel_pstate=passive in the boot kernel line. I'm using it and my hasswell cpu in the laptop has lower temperature than using only intel_pstate (powersave / performance) when there's not much load.
buenaventura 23 Mar, 2017
[quote=qgnox][quote=buenaventura]I
Quoting: Eike
Quoting: buenaventurashedutil <--- INTRUIGING, what is this? I google and it seems like some newfangled stuff? I wonder if that will be even better than Performance!

Still, why does it only go up to 2,00ghz? Says right on the sticker on my lappy "up to 2.4 ghz", bullshiet :P
If you want to use the 2.4GHz with schedutil governor add intel_pstate=passive in the boot kernel line. I'm using it and my hasswell cpu in the laptop has lower temperature than using only intel_pstate (powersave / performance) when there's not much load.

Well my CPU is an AMD A8-6410, so I guess I can't do that right?

I still wonder how I can get it to be 2.4 and not just 2. You would think that that would make a difference.
Hedaja 24 Mar, 2017
I think that's nothing only related to Linux. I did some gaming on my father's laptop for a while. And without setting it to performance I had games running very poorly.
But I always had the CPU-Indicator in Ubuntu and therefore never had troubles changing it. I also do it for other CPU intensive stuff. I still have to take a closer look at schedutil.
elmapul 24 Mar, 2017
Quoting: marcushttps://www.kernel.org/doc/Documentation/cpu-freq/intel-pstate.txt

plain text in 2017? common! i'm a human being! i hate being Treated as a machine!
stan 24 Mar, 2017
  • Supporter
Quoting: elmapulplain text in 2017? common! i'm a human being! i hate being Treated as a machine!
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