Bug 216380

Summary: A way to identify the cause of Turbo Boost unavailability
Product: Power Management Reporter: Artem (knebergish)
Component: intel_pstateAssignee: Kristen (kristen.c.accardi)
Status: NEW ---    
Severity: enhancement CC: bugzilla
Priority: P1    
Hardware: Intel   
OS: Linux   
Kernel Version: 5.18.16-200 (Fedora Kinoite) Subsystem:
Regression: No Bisected commit-id:

Description Artem 2022-08-19 11:03:33 UTC 
Hello.

At the moment, the intel_pstate driver does not provide a way to identify that Turbo Boost has been disabled using the BIOS or is not supported by the system at all. The existing no_turbo attribute does not provide this information, because it also responds to Turbo Boost shutdown due to overheating.

Because of this, for example, in Power Profiles Daemon, to detect Turbo Boost support in the system, developers have to use workarounds that do not give sufficient accuracy (analysis of the turbo_pct attribute):
https://gitlab.freedesktop.org/hadess/power-profiles-daemon/-/blob/main/src/ppd-driver-intel-pstate.c#L111

At the same time, there is information in the driver itself that Turbo Boost has been disabled in the BIOS or is not supported at all in the system:
https://github.com/torvalds/linux/blob/master/drivers/cpufreq/intel_pstate.c#L585

Is there any way to make this information available from the user space? This would allow tools like Power Profiles Daemon to respond more adequately to the capabilities of the system.