From: Peter Zijlstra <peterz@infradead.org>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: 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>,
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>,
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 1/2] arm64: topology: fix arch_freq_get_on_cpu() overflow above 4.19 GHz
Date: Thu, 17 Sep 2026 18:24:09 +0200 [thread overview]
Message-ID: <20260917162409.GQ4121339@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <b7fbe8bc-56b4-4705-b5d8-4a377eb062ee@arm.com>
On Thu, Sep 17, 2026 at 05:55:44PM +0200, Dietmar Eggemann wrote:
> On 17.09.26 17:32, Peter Zijlstra wrote:
> > On Thu, Sep 17, 2026 at 02:51:11PM +0200, Oleg Keri wrote:
>
> [...]
> >> diff --git a/include/linux/topology.h b/include/linux/topology.h
> >> index 709a2dcf4c73..0a4ee12a98d5 100644
> >> --- a/include/linux/topology.h
> >> +++ b/include/linux/topology.h
> >> @@ -351,4 +351,6 @@ static inline unsigned long topology_get_cpu_scale(int cpu)
> >>
> >> void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity);
> >>
> >> +#define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT)
> >
> > This might not be a very good generic helper, since it relies on either
> > of the variables to be u64 for correctness.
>
> So moving it to a static inline function instead?
>
> static inline u64 cap_scale(u64 value, u64 scale)
> {
> return value * scale >> SCHED_CAPACITY_SHIFT;
> }
Yes, that would be much better defined.
next prev parent reply other threads:[~2026-09-17 16:24 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 " 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 [this message]
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
2026-09-17 15:38 ` Oleg Keri
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