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Date: Tue, 25 Jun 2024 13:41:25 +0000
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: <rafael@...nel.org>, <viresh.kumar@...aro.org>, <gautham.shenoy@....com>,
<mario.limonciello@....com>, <perry.yuan@....com>,
<skhan@...uxfoundation.org>, <li.meng@....com>, <ray.huang@....com>
CC: <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Dhananjay
Ugwekar" <Dhananjay.Ugwekar@....com>
Subject: [PATCH 0/2] AMD Pstate driver fixes
1. Handle the nominal freq units inconsistency in amd-pstate-ut, which was
leading to the below error on inserting the amd-pstate-ut module.
[ 4982.498864] amd_pstate_ut: 1 amd_pstate_ut_acpi_cpc_valid success!
[ 4982.498873] amd_pstate_ut: 2 amd_pstate_ut_check_enabled success!
[ 4982.509151] amd_pstate_ut: 3 amd_pstate_ut_check_perf success!
[ 4982.509155] amd_pstate_ut: amd_pstate_ut_check_freq cpu0 max=3709000 >= nominal=2401 > lowest_nonlinear=1903000 > min=400000 > 0, the formula is incorrect!
[ 4982.509157] amd_pstate_ut: 4 amd_pstate_ut_check_freq fail!
2. Setting the scaling_min/max_freq on shared memory CPPC systems was
broken in amd-pstate-epp driver(amd_pstate=active mode). The
scaling_min_freq and scaling_max_freq value was not being propagated to
the shared memory area, so the frequency capping was not being honored.
Tested on a AMD Zen3 Milan machine(shared memory CPPC):
stress-ng is running on the system to keep the CPU utilization at 100%
to test the scaling_max_freq capping.
Before the patch:
We can see below, setting the scaling_max_freq is not taking effect.
linux/tools/power/x86/turbostat# ./turbostat --Summary
turbostat version 2023.11.07 - Len Brown <lenb@...nel.org>
[Snip]
cpu0: cpufreq driver: amd-pstate-epp
cpu0: cpufreq governor: performance
[Snip]
Avg_MHz Busy% Bzy_MHz TSC_MHz IPC IRQ POLL C1 C2 POLL% C1% C2% CorWatt PkgWatt
2620 100.00 2620 2026 0.80 164935 0 0 0 0.00 0.00 0.00 176.07 249.18
2580 100.00 2580 1995 0.80 162208 0 0 0 0.00 0.00 0.00 173.27 245.37
2584 100.00 2584 1998 0.79 162379 0 0 0 0.00 0.00 0.00 173.42 245.68
2577 100.00 2577 1996 0.79 162146 0 0 0 0.00 0.00 0.00 173.15 245.41
2578 100.00 2578 1996 0.80 162025 0 0 0 0.00 0.00 0.00 173.07 245.46
2575 100.00 2575 1996 0.80 162115 0 0 0 0.00 0.00 0.00 172.96 245.41
2576 100.00 2576 1996 0.79 161998 0 0 0 0.00 0.00 0.00 172.87 245.32
linux/tools/power/x86/turbostat# echo 2000000 | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq
2000000
linux/tools/power/x86/turbostat# cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq | uniq
2000000
linux/tools/power/x86/turbostat# ./turbostat --Summary
turbostat version 2023.11.07 - Len Brown <lenb@...nel.org>
[Snip]
cpu0: cpufreq driver: amd-pstate-epp
cpu0: cpufreq governor: performance
[Snip]
Avg_MHz Busy% Bzy_MHz TSC_MHz IPC IRQ POLL C1 C2 POLL% C1% C2% CorWatt PkgWatt
2620 100.00 2620 2038 0.79 166103 0 0 2 0.00 0.00 0.00 175.44 250.96
2566 100.00 2566 1996 0.79 162038 0 0 0 0.00 0.00 0.00 171.79 245.23
2566 100.00 2566 1996 0.79 162289 0 0 0 0.00 0.00 0.00 171.76 245.59
2571 100.00 2571 1996 0.80 162034 0 0 0 0.00 0.00 0.00 171.69 245.44
2566 100.00 2566 1996 0.79 162179 0 0 0 0.00 0.00 0.00 171.62 245.41
2567 100.00 2567 1996 0.79 162028 0 0 0 0.00 0.00 0.00 171.57 245.46
2567 100.00 2567 1996 0.80 162037 0 0 0 0.00 0.00 0.00 171.53 245.41
After applying the patch:
On setting scaling_max_freq at 2GHz, the CPU frequency gets capped at 2GHz.
linux/tools/power/x86/turbostat# ./turbostat --Summary
turbostat version 2023.11.07 - Len Brown <lenb@...nel.org>
[Snip]
cpu0: cpufreq driver: amd-pstate-epp
cpu0: cpufreq governor: performance
[Snip]
Avg_MHz Busy% Bzy_MHz TSC_MHz IPC IRQ POLL C1 C2 POLL% C1% C2% CorWatt PkgWatt
2551 100.00 2551 1956 0.80 165998 0 0 0 0.00 0.00 0.00 171.34 231.22
2713 100.00 2713 2078 0.79 175801 0 0 0 0.00 0.00 0.00 181.92 266.13
2594 100.00 2594 1991 0.79 162183 0 0 1 0.00 0.00 0.00 173.99 244.50
2606 100.00 2606 2003 0.79 162632 0 0 0 0.00 0.00 0.00 174.81 246.51
2599 100.00 2599 1996 0.79 162168 0 0 0 0.00 0.00 0.00 174.05 245.46
linux/tools/power/x86/turbostat# echo 2000000 | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq
2000000
linux/tools/power/x86/turbostat# cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq | uniq
2000000
linux/tools/power/x86/turbostat# ./turbostat --Summary
turbostat version 2023.11.07 - Len Brown <lenb@...nel.org>
[Snip]
cpu0: cpufreq driver: amd-pstate-epp
cpu0: cpufreq governor: performance
[Snip]
Avg_MHz Busy% Bzy_MHz TSC_MHz IPC IRQ POLL C1 C2 POLL% C1% C2% CorWatt PkgWatt
2010 100.00 2010 2030 0.80 165565 0 0 0 0.00 0.00 0.00 101.22 173.52
1975 100.00 1975 1995 0.80 162042 0 0 0 0.00 0.00 0.00 99.03 169.88
1977 100.00 1977 1998 0.80 162559 0 0 0 0.00 0.00 0.00 99.16 170.20
1976 100.00 1976 1996 0.80 162243 0 0 0 0.00 0.00 0.00 99.09 170.08
1976 100.00 1976 1996 0.80 162490 0 0 0 0.00 0.00 0.00 99.17 170.16
1976 100.00 1976 1996 0.80 162056 0 0 0 0.00 0.00 0.00 99.11 170.17
Dhananjay Ugwekar (2):
cpufreq/amd-pstate-ut: Handle the inconsistency between nominal_freq and
other *_freq units
cpufreq/amd-pstate: Fix the scaling_min/max_freq setting on shared
memory CPPC systems
drivers/cpufreq/amd-pstate-ut.c | 12 +++++++-----
drivers/cpufreq/amd-pstate.c | 10 ++++++++++
2 files changed, 17 insertions(+), 5 deletions(-)
--
2.34.1
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