From: Peter Zijlstra <peterz@infradead.org>
To: Pierre Gondois <pierre.gondois@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
linux@armlinux.org.uk, catalin.marinas@arm.com, will@kernel.org,
paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, sudeep.holla@arm.com,
gregkh@linuxfoundation.org, rafael@kernel.org, mingo@redhat.com,
juri.lelli@redhat.com, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
bristot@redhat.com, vschneid@redhat.com, viresh.kumar@linaro.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
linux-pm@vger.kernel.org, conor.dooley@microchip.com,
suagrfillet@gmail.com, ajones@ventanamicro.com, lftan@kernel.org
Subject: Re: [PATCH 4/4] energy_model: use a fixed reference frequency
Date: Tue, 5 Sep 2023 13:33:08 +0200 [thread overview]
Message-ID: <20230905113308.GF28319@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <cd795543-53db-ed14-e9dd-b5738a4f3b9d@arm.com>
On Tue, Sep 05, 2023 at 12:05:30PM +0200, Pierre Gondois wrote:
> Hello Vincent,
> I tried the patch-set on a platform using cppc_cpufreq and that has boosting
> frequencies,
>
> 1-
> On such platform, the CPU capacity comes from the CPPC highest_frequency
> field. The CPU capacity is set to the capacity of the boosting frequency.
> This behaviour is different from DT platforms where the CPU capacity is
> updated whenever the boosting mode is enabled (it seems).
>
> Wouldn't it be better to have CPU max capacities set to their boosting
> capacity as for CPPC base platforms ? It seems the max frequency is always
> available somehow for all the cpufreq drivers with boosting available, i.e.
> acpi-cpufreq, amd-pstate, cppc_cpufreq.
So on Intel we don't use the max (turbo) boost value, but typically end
up picking the 4-core turbo value or something. There's a comment in
arch/x86/kernel/cpu/aperfmperf.c.
Per that comment it probably makes sense to be able to differentiate
between a mobile device and a server, or perhaps we can (ab)use the EAS
enable knob for this distinction?
That is, I'm not sure it makes sense to always pick the highest boost
freqency for ARM64 servers, very much analogous to how we don't do that
on Intel.
next prev parent reply other threads:[~2023-09-05 16:37 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-01 13:03 [PATCH 0/4] consolidate and cleanup CPU capacity Vincent Guittot
2023-09-01 13:03 ` [PATCH 1/4] sched: consolidate and cleanup access to CPU's max compute capacity Vincent Guittot
2023-09-05 11:25 ` Peter Zijlstra
2023-09-14 20:45 ` Dietmar Eggemann
2023-09-15 13:20 ` Vincent Guittot
2023-09-01 13:03 ` [PATCH 2/4] topology: add a new arch_scale_freq_reference Vincent Guittot
2023-09-04 12:35 ` Lukasz Luba
2023-09-18 11:23 ` Vincent Guittot
2023-09-14 21:01 ` Dietmar Eggemann
2023-09-21 9:00 ` Ionela Voinescu
2023-09-25 12:06 ` Vincent Guittot
2023-09-01 13:03 ` [PATCH 3/4] cpufreq/schedutil: use a fixed reference frequency Vincent Guittot
2023-09-02 10:57 ` Conor Dooley
2023-09-02 12:49 ` Vincent Guittot
2023-09-05 11:24 ` Peter Zijlstra
2023-09-05 13:50 ` Vincent Guittot
2023-09-21 9:19 ` Ionela Voinescu
2023-09-25 12:06 ` Vincent Guittot
2023-09-01 13:03 ` [PATCH 4/4] energy_model: " Vincent Guittot
2023-09-04 12:40 ` Lukasz Luba
2023-09-05 10:05 ` Pierre Gondois
2023-09-05 11:33 ` Peter Zijlstra [this message]
2023-09-05 13:16 ` Vincent Guittot
2023-09-14 21:07 ` Dietmar Eggemann
2023-09-15 13:35 ` Vincent Guittot
2023-09-18 20:46 ` Dietmar Eggemann
2023-09-21 10:12 ` Ionela Voinescu
2023-09-21 10:12 ` [PATCH 0/4] consolidate and cleanup CPU capacity Ionela Voinescu
2023-09-25 12:05 ` Vincent Guittot
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