gamemode is unable to change the processor scheduler

[3JlOy-PYCCKUi]

Describe the bug

gamemode is unable to change the processor scheduler

Steps To Reproduce

Steps to reproduce the behavior:

1. set any (schedutil for example) CPU scheduler as default (powerManagement.cpuFreqGovernor = "schedutil";)
2. set programs.gamemode.enable and programs.gamemode.enableRenice to true, set programs.gamemode.settings.general.desiredgov to different CPU scheduler (performance for example)
3. run any command with gamemoderun and check logs of service (journalctl --user -e -u gamemoded), there will be pkexec "Not authorized" errors. Or run /run/wrappers/bin/gamemoded -t it will report that tests failing

Expected behavior

The CPU scheduler is changed to the one specified in programs.gamemode.settings.general.desiredgov for the duration of the execution of the gamemoderun command, and then returned to the default value

Screenshots

If applicable, add screenshots to help explain your problem.

Additional context

tested on nixpkgs commit 317484b1ead87b9c1b8ac5261a8d2dd748a0492d

Notify maintainers

@kira-bruneau

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 6.6.9-xanmod1, NixOS, 24.05 (Uakari), 24.05.20240108.317484b`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.18.1`
 - nixpkgs: `/nix/store/wckjmzcqc347li9r9154nvav82f22g8n-0g53xyh39z3y90p4d8r341wbqyjy1zhl-source`

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[PhilT]

This can also be verified with gamemoded -t:

: Loading config
Loading config file [/nix/store/c9a9kpq0w0cq3j550iblb8r7jj3xpsrn-gamemode-1.8.1/share/gamemode/gamemode.ini]
Loading config file [/etc/gamemode.ini]
: Running tests

:: Basic client tests
:: Passed

:: Dual client tests
gamemode request succeeded and is active
Quitting by request...
:: Passed

:: Gamemoderun and reaper thread tests
...Waiting for child to quit...
...Waiting for reaper thread (reaper_frequency set to 5 seconds)...
:: Passed

:: Supervisor tests
:: Passed

:: Feature tests
::: Verifying CPU governor setting
ERROR: Governor was not set to performance (was actually powersave)!
::: Failed!
::: Verifying Scripts
::: Passed (no scripts configured to run)
::: Verifying GPU Optimisations
::: Passed (gpu optimisations not configured to run)
::: Verifying renice
::: Passed (no renice configured)
::: Verifying ioprio
::: Passed
ERROR: :: Failed!
: Tests Failed!

[kira-bruneau]

This is an upstream change since 1.8, you need to add yourself to the gamemode group to change the processor scheduler.

See:

• Gamemode 1.8.1 can't set CPU governor and GPU Optimisation FeralInteractive/gamemode#452
• Unify privileged group configuration between pam, systemd, & polkit FeralInteractive/gamemode#375

[3JlOy-PYCCKUi]

This is an upstream change since 1.8, you need to add yourself to the gamemode group to change the processor scheduler.

Yes, it works if the group is present, but you need to create the group yourself, maybe it's a good idea to create the group if programs.gamemode.enable = true; (in nixos/modules/programs/gamemode.nix module)? Arch linux, for example, have usr/lib/sysusers.d/gamemode.conf file in gamemode package, that contains g gamemode - - for creating gamemode group

[kira-bruneau]

Oh yep that makes sense! Will open a new PR for that.

[kira-bruneau]

I was also trying to add a NixOS test for it, but you can't set the governor of a CPU within a VM, so I just left it out: #281909