What's Been Going On With CPUFreq & The Scheduler

[phoronix]

Phoronix: What's Been Going On With CPUFreq & The Scheduler

As we've been covering the past few kernel cycles, a lot of low-level improvements have been happening to CPUFreq with going through a redesign and more plus the introduction of a new CPUFreq governor. If you're behind on this subject matter, here's some slides from this week's LinuxCon event that covers the changes...

http://www.phoronix.com/scan.php?page=news_item&px=Schedutil-And-More

[VikingGe]

Thanks for sharing this.

I've just enabled schedutil on both my desktop and my laptop, both AMD based, and I'm actually surprised how much better than ondemand this actually is - *especially* under light load conditions, such as watching video and browsing the web. No more 2.5 GHz when they aren't needed, this keeps the laptop noticably cooler.

[dh04000]

Sounds interesting. Any idea when we can get comparison between kernel versions that compares how this change effects performance? Maybe run video encoding in the background while doing a game performance test and see how it compares?

Also, CPUFreq uses a scheduler now? Sounds like the next project systemd will absorb. /s

[davidbepo]

asking to experts
which scheduler should i use on my i5-5200u?
psate powersave or cpufreq schedutil?

[peppercats]

schedutil killed my IO performance compared to tweaked ondemand + io_is_busy

[Licaon]

'schedutil' and Con's BFS don't mix yet.

[PuckPoltergeist]

Would be interesting to see the comparison of schedutil against ondemand in conjunction with AMD_FREQ_SENSITIVITY

[Sloth]

Thanks for sharing this.

I've just enabled schedutil on both my desktop and my laptop, both AMD based, and I'm actually surprised how much better than ondemand this actually is - *especially* under light load conditions, such as watching video and browsing the web. No more 2.5 GHz when they aren't needed, this keeps the laptop noticably cooler.

Same here, but Intel/Skylake. Playing videos had my CPU 10C cooler compared to pstate.

[halo9en]

Thanks for sharing this.

I've just enabled schedutil on both my desktop and my laptop, both AMD based, and I'm actually surprised how much better than ondemand this actually is - *especially* under light load conditions, such as watching video and browsing the web. No more 2.5 GHz when they aren't needed, this keeps the laptop noticably cooler.

Sounds interesting. Is there a way to switch to schedutil from the kernel boot parameters instead of recompiling with CPU_FREQ_DEFAULT_GOV_SCHEDUTIL enabled?

[PuckPoltergeist]

Sounds interesting. Is there a way to switch to schedutil from the kernel boot parameters instead of recompiling with CPU_FREQ_DEFAULT_GOV_SCHEDUTIL enabled?

You can change this either with 'cpupower frequency-set -g' or directly writing to /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor. For other CPUs than cpu0 you have to adjust the path or specify with '-c'for cpupower.