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    SubjectRe: [PATCH v2 05/11] ARM: topology: use new cpu_power interface
    On 25 May 2014 15:22, Preeti U Murthy <preeti@linux.vnet.ibm.com> wrote:
    > Hi Vincent,
    >
    > Why do we have two interfaces arch_scale_freq_power() and
    > arch_scale_cpu_power()? Does it make sense to consolidate them now ?
    Hi Preeti,

    They don't have the same purpose. arch_scale_cpu_power set the max
    capacity of your CPU whereas arch_scale_freq_power can be used to give
    the current capacity. ARM platform were using arch_scale_freq_power
    because it was the only one available for non SMT system but this
    induces some misunderstanding and some limitation in the
    characterization of a CPUs. This consolidation is a necessary step so
    we can now have the max capacity of a CPU and let
    arch_scale_freq_power for other purpose (or even remove it if
    useless).

    Regards,
    Vincent

    >
    > Regards
    > Preeti U Murthy
    >
    >
    > On 05/23/2014 09:22 PM, Vincent Guittot wrote:
    >> Use the new arch_scale_cpu_power in order to reflect the original capacity of
    >> a CPU instead of arch_scale_freq_power which is more linked to a scaling of
    >> the capacity linked to the frequency.
    >>
    >> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
    >> ---
    >> arch/arm/kernel/topology.c | 4 ++--
    >> 1 file changed, 2 insertions(+), 2 deletions(-)
    >>
    >> diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
    >> index 71e1fec..6cc25a8 100644
    >> --- a/arch/arm/kernel/topology.c
    >> +++ b/arch/arm/kernel/topology.c
    >> @@ -42,7 +42,7 @@
    >> */
    >> static DEFINE_PER_CPU(unsigned long, cpu_scale);
    >>
    >> -unsigned long arch_scale_freq_power(struct sched_domain *sd, int cpu)
    >> +unsigned long arch_scale_cpu_power(struct sched_domain *sd, int cpu)
    >> {
    >> return per_cpu(cpu_scale, cpu);
    >> }
    >> @@ -166,7 +166,7 @@ static void update_cpu_power(unsigned int cpu)
    >> set_power_scale(cpu, cpu_capacity(cpu) / middle_capacity);
    >>
    >> printk(KERN_INFO "CPU%u: update cpu_power %lu\n",
    >> - cpu, arch_scale_freq_power(NULL, cpu));
    >> + cpu, arch_scale_cpu_power(NULL, cpu));
    >> }
    >>
    >> #else
    >>
    >


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