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    SubjectRe: [RFC 1/4] ARM: topology: Add arch_scale_freq_power function
    From
    Hi Vincent,

    On Tue, Jun 12, 2012 at 2:02 PM, Vincent Guittot
    <vincent.guittot@linaro.org> wrote:
    > Add infrastructure to be able to modify the cpu_power of each core
    >
    > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
    > ---
    >  arch/arm/include/asm/topology.h |    2 ++
    >  arch/arm/kernel/topology.c      |   36 +++++++++++++++++++++++++++++++++++-
    >  2 files changed, 37 insertions(+), 1 deletion(-)
    >
    > diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h
    > index 58b8b84..78e4c85 100644
    > --- a/arch/arm/include/asm/topology.h
    > +++ b/arch/arm/include/asm/topology.h
    > @@ -27,11 +27,13 @@ void init_cpu_topology(void);
    >  void store_cpu_topology(unsigned int cpuid);
    >  const struct cpumask *cpu_coregroup_mask(int cpu);
    >
    > +void set_power_scale(unsigned int cpu, unsigned long power);
    >  #else
    >
    >  static inline void init_cpu_topology(void) { }
    >  static inline void store_cpu_topology(unsigned int cpuid) { }
    >
    > +static inline void set_power_scale(unsigned int cpu, unsigned long power) { }
    >  #endif
    >
    >  #include <asm-generic/topology.h>
    > diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
    > index 8200dea..00301a7 100644
    > --- a/arch/arm/kernel/topology.c
    > +++ b/arch/arm/kernel/topology.c
    > @@ -22,6 +22,35 @@
    >  #include <asm/cputype.h>
    >  #include <asm/topology.h>
    >
    > +/*
    > + * cpu power scale management
    > + */
    > +
    > +/*
    > + * cpu power table
    > + * This per cpu data structure describes the relative capacity of each core.
    > + * On a heteregenous system, cores don't have the same computation capacity
    > + * and we reflect that difference in the cpu_power field so the scheduler can
    > + * take this difference into account for load balance. A per cpu structure is
    > + * preferred because each cpu is mainly using its own cpu_power even it's not
    > + * always true because of nohz_idle_balance
    The end of the comment is unclear IMO; Can you give more details on
    the relation between cpu_power and nohz_idle_balance?

    Regards,
    Jean
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