linux: Switch to schedutil governor #42330

NeQuissimus · 2018-06-21T15:05:42Z

Motivation for this change

Since 4.9, the Linux kernel has included the "schedutil" CPU governor (in its current implementation): https://cateee.net/lkddb/web-lkddb/CPU_FREQ_GOV_SCHEDUTIL.html

This governor adjusts the CPU frequency based on utilization data provided by the scheduler.

Switching to this governor should allow for energy-savings while still making "high-performance" possible.

Closes #41003

Things done

Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
Built on platform(s)
- NixOS
- macOS
- other Linux distributions
Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
Tested execution of all binary files (usually in ./result/bin/)
Fits CONTRIBUTING.md.

Add these to my config:

boot.kernelParams = [ "intel_pstate=passive" ];
powerManagement.cpuFreqGovernor = "schedutil";

λ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
schedutil
λ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
performance schedutil
λ systemctl status cpufreq.service
● cpufreq.service - CPU Frequency Governor Setup
   Loaded: loaded (/nix/store/lzk05z7a3l0gslpsbrmh8qcacmvzw65x-unit-cpufreq.service/cpufreq.service; enabled; vendor preset: enabled)
   Active: active (exited) since Thu 2018-06-21 10:30:01 EDT; 35min ago
  Process: 838 ExecStart=/nix/store/c1zaswjv476fyxdkl78yr6816wnp9qrb-cpupower-4.16.16/bin/cpupower frequency-set -g schedutil (code=exited, status=0/SUCCESS)
 Main PID: 838 (code=exited, status=0/SUCCESS)

Jun 21 10:30:01 nixus-desktop systemd[1]: Starting CPU Frequency Governor Setup...
Jun 21 10:30:01 nixus-desktop cpupower[838]: Setting cpu: 0
Jun 21 10:30:01 nixus-desktop cpupower[838]: Setting cpu: 1
Jun 21 10:30:01 nixus-desktop cpupower[838]: Setting cpu: 2
Jun 21 10:30:01 nixus-desktop cpupower[838]: Setting cpu: 3
Jun 21 10:30:01 nixus-desktop cpupower[838]: Setting cpu: 4
Jun 21 10:30:01 nixus-desktop cpupower[838]: Setting cpu: 5
Jun 21 10:30:01 nixus-desktop cpupower[838]: Setting cpu: 6
Jun 21 10:30:01 nixus-desktop cpupower[838]: Setting cpu: 7
Jun 21 10:30:01 nixus-desktop systemd[1]: Started CPU Frequency Governor Setup.

GrahamcOfBorg · 2018-06-21T15:19:28Z

No attempt on x86_64-darwin (full log)

The following builds were skipped because they don't evaluate on x86_64-darwin: linux

Partial log (click to expand)

while evaluating the attribute 'linux_4_14' at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/pkgs/top-level/all-packages.nix:13599:3:
while evaluating 'callPackageWith' at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/lib/customisation.nix:113:35, called from /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/pkgs/top-level/all-packages.nix:13599:16:
while evaluating 'makeOverridable' at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/lib/customisation.nix:72:24, called from /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/lib/customisation.nix:117:8:
while evaluating anonymous function at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/pkgs/os-specific/linux/kernel/linux-4.14.nix:1:1, called from /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/lib/customisation.nix:74:12:
while evaluating 'buildLinux' at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/pkgs/top-level/all-packages.nix:13914:16, called from /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/pkgs/os-specific/linux/kernel/linux-4.14.nix:5:1:
while evaluating 'callPackageWith' at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/lib/customisation.nix:113:35, called from /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/pkgs/top-level/all-packages.nix:13914:23:
while evaluating 'makeOverridable' at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/lib/customisation.nix:72:24, called from /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/lib/customisation.nix:117:8:
while evaluating anonymous function at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/pkgs/os-specific/linux/kernel/generic.nix:1:1, called from /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/lib/customisation.nix:74:12:
assertion failed at /private/var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/builder/lnl7-mac/pkgs/os-specific/linux/kernel/generic.nix:48:1

GrahamcOfBorg · 2018-06-21T15:42:51Z

Success on aarch64-linux (full log)

Attempted: linux

Partial log (click to expand)

wrong ELF type
wrong ELF type
wrong ELF type
wrong ELF type
wrong ELF type
wrong ELF type
wrong ELF type
wrong ELF type
cannot find section .dynamic
/nix/store/x1v2mnr78smxfiw3dhkm4nccr0z5r8fh-linux-4.14.51

GrahamcOfBorg · 2018-06-21T15:53:12Z

Failure on x86_64-linux (full log)

Attempted: linux

Partial log (click to expand)

  CC [M]  drivers/usb/host/isp1362-hcd.o
  CC [M]  drivers/staging/lustre/lustre/llite/vvp_dev.o
  CC [M]  drivers/staging/lustre/lustre/lmv/lmv_intent.o
  CC [M]  drivers/scsi/esp_scsi.o
  CC [M]  drivers/usb/host/ohci-hcd.o
  CC [M]  drivers/staging/lustre/lustre/llite/vvp_page.o
  CC [M]  drivers/staging/lustre/lustre/lmv/lmv_fld.o
  CC [M]  drivers/scsi/am53c974.o
building of '/nix/store/vsiillchn2k6di0nnrwaazp226pg2pw9-linux-4.14.51.drv' timed out after 1800 seconds
error: build of '/nix/store/vsiillchn2k6di0nnrwaazp226pg2pw9-linux-4.14.51.drv' failed

edolstra · 2018-06-21T16:11:19Z

If this is a fairly new scheduler, is it a good idea to make it the default? What do the kernel developers recommend? What do other distributions do?

NeQuissimus · 2018-06-21T16:37:38Z

I only checked with Arch and Ubuntu, and they both use schedutil as the default.

worldofpeace · 2018-07-14T13:13:01Z

pkgs/os-specific/linux/kernel/common-config.nix

@@ -75,6 +75,11 @@ with stdenv.lib;
  ''}
  INTEL_IDLE y
  CPU_FREQ_DEFAULT_GOV_PERFORMANCE y
+  ${optionalString (versionAtLeast version "4.9") ''
+    CPU_FREQ_GOV_SCHEDUTIL y


@NeQuissimus
Since its been almost a month without feedback from other people here, I think it would be fine to just allow people to use schedutil but not change the default governor yet. Currently no one can use this.

I agree with worldofpeace. This should probably be split into two pull requests, one allowing users to use schedutil in the first place, and another that suggests changing the defaults.
That will also allow people to test things out, and / or draw their attention to the fact, that this exists at all.

orivej · 2018-07-15T02:18:48Z

It's good to build schedutil (probably as a module, like other governors), but it is not an alternative to performance and should not replace it. The default built into the kernel does not matter on NixOS anyway because nixos-generate-config configures powerManagement.cpuFreqGovernor that overrides it, currently to ondemand or powersave; this list may be changed to prefer schedutil. Note that the unset powerManagement.cpuFreqGovernor is documented to mean performance.

xaverdh · 2018-07-15T03:52:54Z

It's good to build schedutil (probably as a module, like other governors), [...]

Note: As I understand it now, on recent kernel versions schedutil can no longer be built as a module.

NeQuissimus · 2018-07-30T17:48:31Z

As mentioned above, schedutil cannot be built as a module.
Not sure how we should proceed with this. Any suggestions?
Set CPU_FREQ_GOV_SCHEDUTIL but not CPU_FREQ_DEFAULT_GOV_SCHEDUTIL (if that is valid)?

xeji · 2018-08-30T08:37:40Z

For now, let's enable schedutil but not make it the default, and review the default for 19.03 after people have used it for a while.

vcunat · 2018-08-30T09:28:24Z

Right, e6a37e3. We can continue the discussion about the default, though that might be better after several months (I don't really know, I haven't researched pros and cons).

- it can't be built as a module - it's not set as the default yet - for discussion see #42330

brainrake · 2018-09-01T12:15:26Z

Can we close this?

enabling schedutil is solved by e6a37e3
setting it as the default as it is done in this PR is not effective
setting it as the default should be a separate PR

Thanks!

linux: Switch to schedutil governor

fb5a33b

NeQuissimus added 0.kind: enhancement 6.topic: nixos 6.topic: kernel 9.needs: community feedback labels Jun 21, 2018

GrahamcOfBorg added 10.rebuild-darwin: 0 10.rebuild-linux: 501+ and removed 6.topic: kernel 6.topic: nixos labels Jun 21, 2018

NeQuissimus added this to the 18.09 milestone Jun 22, 2018

worldofpeace reviewed Jul 14, 2018

View reviewed changes

fpletz approved these changes Jul 15, 2018

View reviewed changes

xeji added the 2.status: merge conflict label Aug 7, 2018

vcunat added a commit that referenced this pull request Aug 30, 2018

linux: build with SCHEDUTIL governor

e6a37e3

- it can't be built as a module - it's not set as the default yet - for discussion see #42330

samueldr modified the milestones: 18.09, 19.03 Aug 30, 2018

vcunat closed this Sep 1, 2018

NeQuissimus deleted the schedutil branch February 14, 2021 01:16

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linux: Switch to schedutil governor #42330

linux: Switch to schedutil governor #42330

NeQuissimus commented Jun 21, 2018 •

edited

GrahamcOfBorg commented Jun 21, 2018

GrahamcOfBorg commented Jun 21, 2018

GrahamcOfBorg commented Jun 21, 2018

edolstra commented Jun 21, 2018

NeQuissimus commented Jun 21, 2018

worldofpeace Jul 14, 2018

xaverdh Jul 14, 2018 •

edited

orivej commented Jul 15, 2018 •

edited

xaverdh commented Jul 15, 2018

NeQuissimus commented Jul 30, 2018

xeji commented Aug 30, 2018

vcunat commented Aug 30, 2018

brainrake commented Sep 1, 2018 •

edited

linux: Switch to schedutil governor #42330

linux: Switch to schedutil governor #42330

Conversation

NeQuissimus commented Jun 21, 2018 • edited

Motivation for this change

Things done

GrahamcOfBorg commented Jun 21, 2018

GrahamcOfBorg commented Jun 21, 2018

GrahamcOfBorg commented Jun 21, 2018

edolstra commented Jun 21, 2018

NeQuissimus commented Jun 21, 2018

worldofpeace Jul 14, 2018

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xaverdh Jul 14, 2018 • edited

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orivej commented Jul 15, 2018 • edited

xaverdh commented Jul 15, 2018

NeQuissimus commented Jul 30, 2018

xeji commented Aug 30, 2018

vcunat commented Aug 30, 2018

brainrake commented Sep 1, 2018 • edited

NeQuissimus commented Jun 21, 2018 •

edited

xaverdh Jul 14, 2018 •

edited

orivej commented Jul 15, 2018 •

edited

brainrake commented Sep 1, 2018 •

edited