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    SubjectRe: [RFC 3/4] ARM: topology: Update cpu_power according to DT information
    From
    Vincent,

    On Tue, Jun 12, 2012 at 2:02 PM, Vincent Guittot
    <vincent.guittot@linaro.org> wrote:
    > Use cpu compatibility field and clock-frequency field of DT to
    > estimate the capacity of each core of the system
    >
    > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
    > ---
    >  arch/arm/kernel/topology.c |  122 ++++++++++++++++++++++++++++++++++++++++++++
    >  1 file changed, 122 insertions(+)
    >
    > diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
    > index 2f85a64..0c2aee4 100644
    > --- a/arch/arm/kernel/topology.c
    > +++ b/arch/arm/kernel/topology.c
    > @@ -17,6 +17,7 @@
    >  #include <linux/percpu.h>
    >  #include <linux/node.h>
    >  #include <linux/nodemask.h>
    > +#include <linux/of.h>
    >  #include <linux/sched.h>
    >
    >  #include <asm/cputype.h>
    > @@ -47,6 +48,122 @@ void set_power_scale(unsigned int cpu, unsigned long power)
    >        per_cpu(cpu_scale, cpu) = power;
    >  }
    >
    > +#ifdef CONFIG_OF
    > +struct cpu_efficiency {
    > +       const char *compatible;
    > +       unsigned long efficiency;
    > +};
    > +
    > +/*
    > + * Table of relative efficiency of each processors
    > + * The efficiency value must fit in 20bit. The final
    > + * cpu_scale value must be in the range [1:2048[.
    Typo here.

    > + * Processors that are not defined in the table,
    > + * use the default SCHED_POWER_SCALE value for cpu_scale.
    > + */
    > +struct cpu_efficiency table_efficiency[] = {
    > +       {"arm,cortex-a15", 3891},
    > +       {"arm,cortex-a7",  2048},
    How are those results measured or computed? Is this purely related to
    the number crunching performance?

    Also more generally what if the cores frequencies are changing?

    Regards,
    Jean
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