linux-kernel - Re: [PATCH v2 0/5] cpufreq: intel_pstate: Address some HWP-related oddities

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Date:   Mon, 24 Aug 2020 16:56:29 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Doug Smythies <dsmythies@...us.net>
Subject: Re: [PATCH v2 0/5] cpufreq: intel_pstate: Address some HWP-related
 oddities

On Mon, 2020-08-24 at 19:39 +0200, Rafael J. Wysocki wrote:
> Hi All,
> 
> The v2 is here to address feedback from Doug and one issue found by
> me.
> 
> The purpose of this series is to address some peculiarities related
> to
> taking CPUs offline/online and switching between different operation
> modes with HWP enabled that have become visible after allowing the
> driver to work in the passive mode with HWP enabled in 5.9-rc1 (and
> one that was there earlier, but can be addressed easily after the
> changes madein 5.9-rc1).
> 
> Please refer to the patch changelogs for details.
> 
> For easier testing/review, the series is available from the git
> branch at:
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
>  intel_pstate-testing
> 

Applied these patches to 5.9-rc2

- After s3  limits got messed up.
 # cat /sys/power/mem_sleep 
s2idle [deep]

- In the dmesg unchecked MSR for HWP register

1.
Before test

sudo rdmsr -a 0x774
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002b0c
80002b0c
80002d0d
7f002b0c



cd /sys/devices/system/cpu/intel_pstate/
[root@...pl-perf-test-skx-i9 intel_pstate]# grep . *
hwp_dynamic_boost:0
max_perf_pct:100
min_perf_pct:27
no_turbo:0
num_pstates:32
status:active
turbo_pct:32

cd ../cpu1/cpufreq/
[root@...pl-perf-test-skx-i9 cpufreq]# grep . *
affected_cpus:1
base_frequency:3300000
cpuinfo_max_freq:4300000
cpuinfo_min_freq:1200000
cpuinfo_transition_latency:0
energy_performance_available_preferences:default performance
balance_performance balance_power power 
energy_performance_preference:balance_performance
related_cpus:1
scaling_available_governors:performance powersave
scaling_cur_freq:1200000
scaling_driver:intel_pstate
scaling_governor:powersave
scaling_max_freq:4300000
scaling_min_freq:1200000
scaling_setspeed:<unsupported>


2. Now change the EPP

# echo 127 > energy_performance_preference
sudo rdmsr -a 0x774
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002b0c
80002b0c
80002d0d

Good here

3. Offline/online good

[root@...pl-perf-test-skx-i9 cpufreq]# echo 0 >
/sys/devices/system/cpu/cpu1/online 
[root@...pl-perf-test-skx-i9 cpufreq]# echo ` >
/sys/devices/system/cpu/cpu1/online 
> echo ` > /sys/devices/system/cpu/cpu1/online ^C
[root@...pl-perf-test-skx-i9 cpufreq]# echo 1 >
/sys/devices/system/cpu/cpu1/online 

 sudo rdmsr -a 0x774
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002b0c
80002b0c
80002d0d
7f002b0c

Good. Online restored the setting

4. Now S3

rtcwake -m mem -s 10

All limits are now messed up

sudo rdmsr -a 0x774
80002b0c
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00

5. Now switch to passive
Again bad, some CPU max/min is 0

sudo rdmsr -a 0x774
80002b0d
7f002b0f
80002b0c
80002d0e
80002b0c
80002b0d
80002b0f
80002b2b
80002b0c
80002d1d
80000000
80002b0c
80002b0c
80000000
80000000
80000000
80000000
80000000
80000000
80000000

6.
Switched back to active to restore back

Lost EPP setting but rest are good.

sudo rdmsr -a 0x774
80002b0c
7f002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002d0c
80002b0c
80002b0c
80002b0c
80002b0c
80002b0c
80002d0d

7. S3 again

rtcwake -m mem -s 10

Again messed up

 sudo rdmsr -a 0x774
80002b0c
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00
8000ff00

This time dmesg didn't have unchecked MSR in dmesg (I think because I
didn't change EPP before)

Thanks,
Srinivas

> Thanks,
> Rafael
> 
> 
> 

View attachment "dmesg.txt" of type "text/plain" (15375 bytes)