RE: [PATCH v6] cpufreq: intel_pstate: Implement passive mode with HWP enabled

Doug Smythies
2020-08-04T17:07:38Z

Hi Rafael,

I was just writing you about V5 when this V6 came.

On 2020.08.04 08:11 Rafael J. Wysocki wrote:
...
> This is on top of the material already in the mainline.

Oh, should have read that part better,
but did get there in the end.
...
> v5 -> v6:
> * Fix the problem with the EPP setting via sysfs not working with the
> performance and powersave governors by stopping and restarting the
> governor around the sysfs-based EPP updates in the passive mode.
> * Because of that, use the epp_cached field just for avoiding the above
> if the new EPP value for the given CPU is the same as the old one.
> * Export cpufreq_start/stop_governor() from the core (for the above).

EPP is still not right.
I am not messing with it at all, just observing via my msr-decoder.

I booted without any intel_pstate related directives for the
kernel command line. The below is as expected (performance gov.):

# /home/doug/c/msr-decoder
How many CPUs?: 6
8.) 0x198: IA32_PERF_STATUS : CPU 0-5 : 46 : 46 : 46 : 46 : 46 : 46 :
B.) 0x770: IA32_PM_ENABLE: 1 : HWP enable
1.) 0x19C: IA32_THERM_STATUS: 88450000
2.) 0x1AA: MSR_MISC_PWR_MGMT: 401CC0 EIST enabled Coordination enabled OOB Bit 8 reset OOB Bit 18 reset
3.) 0x1B1: IA32_PACKAGE_THERM_STATUS: 88430000
4.) 0x64F: MSR_CORE_PERF_LIMIT_REASONS: 0
A.) 0x1FC: MSR_POWER_CTL: 3C005D : C1E disable : EEO disable : RHO disable
5.) 0x771: IA32_HWP_CAPABILITIES (performance): 109252E : high 46 : guaranteed 37 : efficient 9 : lowest 1
6.) 0x774: IA32_HWP_REQUEST: CPU 0-5 :
raw: 00002E2E : 00002E2E : 00002E2E : 00002E2E : 00002E2E : 00002E2E :
min: 46 : 46 : 46 : 46 : 46 : 46 :
max: 46 : 46 : 46 : 46 : 46 : 46 :
des: 0 : 0 : 0 : 0 : 0 : 0 :
epp: 0 : 0 : 0 : 0 : 0 : 0 :
act: 0 : 0 : 0 : 0 : 0 : 0 :
7.) 0x777: IA32_HWP_STATUS: 4 : high 4 : guaranteed 0 : efficient 0 : lowest 0

and then switched to passive mode later. EPP is not as expected. Expect 0
(performance mode):

# /home/doug/c/msr-decoder
How many CPUs?: 6
8.) 0x198: IA32_PERF_STATUS : CPU 0-5 : 46 : 46 : 46 : 46 : 46 : 46 :
B.) 0x770: IA32_PM_ENABLE: 1 : HWP enable
1.) 0x19C: IA32_THERM_STATUS: 88440000
2.) 0x1AA: MSR_MISC_PWR_MGMT: 401CC0 EIST enabled Coordination enabled OOB Bit 8 reset OOB Bit 18 reset
3.) 0x1B1: IA32_PACKAGE_THERM_STATUS: 88420000
4.) 0x64F: MSR_CORE_PERF_LIMIT_REASONS: 0
A.) 0x1FC: MSR_POWER_CTL: 3C005D : C1E disable : EEO disable : RHO disable
5.) 0x771: IA32_HWP_CAPABILITIES (performance): 108252E : high 46 : guaranteed 37 : efficient 8 : lowest 1
6.) 0x774: IA32_HWP_REQUEST: CPU 0-5 :
raw: FF002E2E : FF002E2E : FF002E2E : FF002E2E : FF002E2E : FF002E2E :
min: 46 : 46 : 46 : 46 : 46 : 46 :
max: 46 : 46 : 46 : 46 : 46 : 46 :
des: 0 : 0 : 0 : 0 : 0 : 0 :
epp: 255 : 255 : 255 : 255 : 255 : 255 :
act: 0 : 0 : 0 : 0 : 0 : 0 :
7.) 0x777: IA32_HWP_STATUS: 4 : high 4 : guaranteed 0 : efficient 0 : lowest 0

Then switched to ondemand governor, and put 100% load on 2 CPUs.
EPP is not as expected, which I don't actually know what to expect,
but assume 128:

# /home/doug/c/msr-decoder
How many CPUs?: 6
8.) 0x198: IA32_PERF_STATUS : CPU 0-5 : 46 : 46 : 46 : 46 : 46 : 46 :
B.) 0x770: IA32_PM_ENABLE: 1 : HWP enable
1.) 0x19C: IA32_THERM_STATUS: 883B0000
2.) 0x1AA: MSR_MISC_PWR_MGMT: 401CC0 EIST enabled Coordination enabled OOB Bit 8 reset OOB Bit 18 reset
3.) 0x1B1: IA32_PACKAGE_THERM_STATUS: 882B0000
4.) 0x64F: MSR_CORE_PERF_LIMIT_REASONS: 0
A.) 0x1FC: MSR_POWER_CTL: 3C005D : C1E disable : EEO disable : RHO disable
5.) 0x771: IA32_HWP_CAPABILITIES (performance): 10B252E : high 46 : guaranteed 37 : efficient 11 : lowest 1
6.) 0x774: IA32_HWP_REQUEST: CPU 0-5 :
raw: FF002E09 : FF002E0C : FF002E2E : FF002E08 : FF002E2E : FF002E18 :
min: 9 : 12 : 46 : 8 : 46 : 24 :
max: 46 : 46 : 46 : 46 : 46 : 46 :
des: 0 : 0 : 0 : 0 : 0 : 0 :
epp: 255 : 255 : 255 : 255 : 255 : 255 :
act: 0 : 0 : 0 : 0 : 0 : 0 :
7.) 0x777: IA32_HWP_STATUS: 4 : high 4 : guaranteed 0 : efficient 0 : lowest 0

For what it's worth, Kernel:

78b39581ed85 (HEAD -> dtemp) cpufreq: intel_pstate: Implement passive mode with HWP enabled
c0842fbc1b18 (origin/master, origin/HEAD, master) random32: move the pseudo-random 32-bit definitions to prandom.h
2baa85d6927d Merge tag 'acpi-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
04084978003c Merge tag 'pm-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

... Doug