From: Viresh Kumar <viresh.kumar@linaro.org>
To: Qian Cai <quic_qiancai@quicinc.com>
Cc: Rafael Wysocki <rjw@rjwysocki.net>,
Ionela Voinescu <ionela.voinescu@arm.com>,
Ben Segall <bsegall@google.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>, Mel Gorman <mgorman@suse.de>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Sudeep Holla <sudeep.holla@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Will Deacon <will@kernel.org>,
linux-pm@vger.kernel.org, linux-acpi@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Paul E. McKenney" <paulmck@kernel.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [PATCH V3 0/4] cpufreq: cppc: Add support for frequency invariance
Date: Tue, 22 Jun 2021 12:22:59 +0530 [thread overview]
Message-ID: <20210622065259.nw3e7ajwgzgnlm5e@vireshk-i7> (raw)
In-Reply-To: <09a39f5c-b47b-a931-bf23-dc43229fb2dd@quicinc.com>
On 21-06-21, 16:48, Qian Cai wrote:
> Viresh, this series works fine on my quick tests so far.
Thanks for testing.
> BTW, I
> noticed some strange things even with the series applied mentioned
> below when reading acpi_cppc vs cpufreq sysfs. Do you happen to know
> are those just hardware/firmware issues because Linux just
> faithfully exported the register values?
The values are exported by drivers/acpi/cppc_acpi.c I believe and they
look to be based on simple register reads.
> == Arm64 server Foo ==
> CPU max MHz: 3000.0000
> CPU min MHz: 1000.0000
>
> /sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf
> 300
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_freq
> 1000
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_nonlinear_perf
> 200
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_perf
> 100
> /sys/devices/system/cpu/cpu0/acpi_cppc/nominal_freq <--- should be 3000?
> 2800
> /sys/devices/system/cpu/cpu0/acpi_cppc/nominal_perf <--- should be 300?
> 280
nominal-perf is max perf, and highest-perf is boost-perf. Same goes
with nominal-freq (i.e. policy->max).
So 280 and 2800 look to be the correct values, 300 and 3000 come with
boost enabled. Look at the first entry, highest_perf.
> /sys/devices/system/cpu/cpu0/acpi_cppc/reference_perf
> 100
>
> == Arm64 server Bar ==
> CPU max MHz: 3000.0000
> CPU min MHz: 375.0000
>
> /sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf <--- should be 3000? There is no cpufreq boost.
> 3300
This isn't exported by cpufreq driver but acpi, and it just exports
hardware values of highest_perf (with boost i.e.). cpufreq may or
may not use this to support boost.
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_freq <--- don't understand why 0.
> 0
Because corresponding hardware registers aren't implemented for your
platform, this is the function that reads these registers:
int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
{
...
/* Read optional lowest and nominal frequencies if present */
if (CPC_SUPPORTED(low_freq_reg))
cpc_read(cpunum, low_freq_reg, &low_f);
if (CPC_SUPPORTED(nom_freq_reg))
cpc_read(cpunum, nom_freq_reg, &nom_f);
perf_caps->lowest_freq = low_f;
perf_caps->nominal_freq = nom_f;
}
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_nonlinear_perf
> 375
> /sys/devices/system/cpu/cpu0/acpi_cppc/lowest_perf
> 375
> /sys/devices/system/cpu/cpu0/acpi_cppc/nominal_freq <--- ditto
> 0
> /sys/devices/system/cpu/cpu0/acpi_cppc/nominal_perf
> 3000
> /sys/devices/system/cpu/cpu0/acpi_cppc/reference_perf
> 100
--
viresh
next prev parent reply other threads:[~2021-06-22 6:53 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-21 9:19 [PATCH V3 0/4] cpufreq: cppc: Add support for frequency invariance Viresh Kumar
2021-06-21 9:19 ` [PATCH V3 1/4] cpufreq: cppc: Fix potential memleak in cppc_cpufreq_cpu_init Viresh Kumar
2021-06-23 13:44 ` Ionela Voinescu
2021-06-24 2:08 ` Viresh Kumar
2021-06-24 2:10 ` [PATCH V3.1 " Viresh Kumar
2021-06-25 10:33 ` Ionela Voinescu
2021-06-21 9:19 ` [PATCH V3 2/4] cpufreq: cppc: Pass structure instance by reference Viresh Kumar
2021-06-23 13:45 ` Ionela Voinescu
2021-06-24 2:22 ` Viresh Kumar
2021-06-25 10:30 ` Ionela Voinescu
2021-06-21 9:19 ` [PATCH V3 3/4] arch_topology: Avoid use-after-free for scale_freq_data Viresh Kumar
2021-06-23 13:50 ` Ionela Voinescu
2021-06-21 9:19 ` [PATCH V3 4/4] cpufreq: CPPC: Add support for frequency invariance Viresh Kumar
2021-06-24 9:48 ` Ionela Voinescu
2021-06-24 13:04 ` Viresh Kumar
2021-06-25 8:54 ` Ionela Voinescu
2021-06-25 16:54 ` Viresh Kumar
2021-06-28 10:49 ` Ionela Voinescu
2021-06-29 4:32 ` Viresh Kumar
2021-06-29 8:47 ` Ionela Voinescu
2021-06-29 8:53 ` Viresh Kumar
2021-06-21 20:48 ` [PATCH V3 0/4] cpufreq: cppc: " Qian Cai
2021-06-22 6:52 ` Viresh Kumar [this message]
2021-06-23 4:16 ` Viresh Kumar
2021-06-23 12:57 ` Qian Cai
2021-06-24 2:54 ` Viresh Kumar
2021-06-24 9:49 ` Vincent Guittot
2021-06-24 10:48 ` Ionela Voinescu
2021-06-24 11:15 ` Vincent Guittot
2021-06-24 11:23 ` Ionela Voinescu
2021-06-24 11:59 ` Vincent Guittot
2021-06-24 15:17 ` Qian Cai
2021-06-25 10:21 ` Ionela Voinescu
2021-06-25 13:31 ` Qian Cai
2021-06-25 14:37 ` Ionela Voinescu
2021-06-25 16:56 ` Qian Cai
2021-06-26 2:29 ` Qian Cai
2021-06-26 13:41 ` Qian Cai
2021-06-29 4:55 ` Viresh Kumar
2021-06-29 4:52 ` Viresh Kumar
2021-06-29 9:06 ` Ionela Voinescu
2021-06-29 13:38 ` Qian Cai
2021-06-29 4:45 ` Viresh Kumar
2021-06-24 20:44 ` Qian Cai
2021-06-28 11:54 ` Ionela Voinescu
2021-06-28 12:14 ` Vincent Guittot
2021-06-28 12:17 ` Vincent Guittot
2021-06-28 13:08 ` Ionela Voinescu
2021-06-28 21:37 ` Ionela Voinescu
2021-06-29 8:45 ` Vincent Guittot
2021-06-29 5:20 ` Viresh Kumar
2021-06-29 8:46 ` Ionela Voinescu
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