From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Oleg Keri <okerixx@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
K Prateek Nayak <kprateek.nayak@amd.com>,
Sumit Gupta <sumitg@nvidia.com>,
Beata Michalska <beata.michalska@arm.com>,
Prasanna Kumar T S M <ptsm@linux.microsoft.com>,
Sudeep Holla <sudeep.holla@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Danilo Krummrich <dakr@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, driver-core@lists.linux.dev,
Viresh Kumar <viresh.kumar@linaro.org>,
linux-pm@vger.kernel.org
Subject: Re: [PATCH v4 2/2] arch_topology: use the boost frequencies for capacity_freq_ref
Date: Thu, 17 Sep 2026 16:34:58 +0200 [thread overview]
Message-ID: <bddc9273-fe02-4984-bfe9-5078e9e6e111@arm.com> (raw)
In-Reply-To: <20260917125112.2283-3-okerixx@gmail.com>
On 17.09.26 14:51, Oleg Keri wrote:
> capacity_freq_ref is latched from policy->cpuinfo.max_freq by
> init_cpu_capacity_callback() on CPUFREQ_CREATE_POLICY.
> cpufreq_frequency_table_cpuinfo() excludes CPUFREQ_BOOST_FREQ entries
> while boost is disabled, so on a system that boots with boost off the
> reference is the non-boost maximum and stays there.
>
> Once boost is enabled the CPU runs above its reference. On arm64, where
> the AMU drives frequency invariance, amu_scale_freq_tick() caps the scale
> at SCHED_CAPACITY_SCALE, so the scheduler cannot tell a boosted CPU from
> one at the sustained maximum, and arch_freq_get_on_cpu() cannot report
> above the reference, so cpuinfo_avg_freq is pinned to it.
>
> CPPC based systems do not have the problem: their reference comes from
> highest_perf, and a disabled boost shows up as cpufreq pressure. Do the
> same for frequency table drivers and take the highest valid table entry,
> boost entries included, as the reference. With boost off
> cpufreq_update_pressure() then reports the difference as pressure.
Ah, you want to fix this for 'frequency table' drivers.
IMHO,
https://lore.kernel.org/r/20260908-schedutil-boost-frequency-handling-v2-0-25312a713699@oss.qualcomm.com
is trying the same at the moment.
[...]
next prev parent reply other threads:[~2026-09-17 14:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-17 12:51 [PATCH v4 0/2] arm64/cpufreq: report and track frequencies above 4.19 GHz Oleg Keri
2026-09-17 12:51 ` [PATCH v4 1/2] arm64: topology: fix arch_freq_get_on_cpu() overflow " Oleg Keri
2026-09-17 15:32 ` Peter Zijlstra
2026-09-17 15:55 ` Dietmar Eggemann
2026-09-17 16:24 ` Peter Zijlstra
2026-09-17 12:51 ` [PATCH v4 2/2] arch_topology: use the boost frequencies for capacity_freq_ref Oleg Keri
2026-09-17 14:34 ` Dietmar Eggemann [this message]
2026-09-17 15:38 ` Oleg Keri
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