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    Subject[PATCH v3 1/5] ARM: topology: Add arch_scale_freq_power function
    Date
    Add infrastructure to be able to modify the cpu_power of each core

    Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
    ---
    arch/arm/kernel/topology.c | 38 +++++++++++++++++++++++++++++++++++++-
    1 file changed, 37 insertions(+), 1 deletion(-)

    diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
    index 8200dea..51f23b3 100644
    --- a/arch/arm/kernel/topology.c
    +++ b/arch/arm/kernel/topology.c
    @@ -22,6 +22,37 @@
    #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 during load balance. A per cpu structure
    + * is preferred because each CPU updates its own cpu_power field during the
    + * load balance except for idle cores. One idle core is selected to run the
    + * rebalance_domains for all idle cores and the cpu_power can be updated
    + * during this sequence.
    + */
    +static DEFINE_PER_CPU(unsigned long, cpu_scale);
    +
    +unsigned long arch_scale_freq_power(struct sched_domain *sd, int cpu)
    +{
    + return per_cpu(cpu_scale, cpu);
    +}
    +
    +static void set_power_scale(unsigned int cpu, unsigned long power)
    +{
    + per_cpu(cpu_scale, cpu) = power;
    +}
    +
    +/*
    + * cpu topology management
    + */
    +
    #define MPIDR_SMP_BITMASK (0x3 << 30)
    #define MPIDR_SMP_VALUE (0x2 << 30)

    @@ -41,6 +72,9 @@
    #define MPIDR_LEVEL2_MASK 0xFF
    #define MPIDR_LEVEL2_SHIFT 16

    +/*
    + * cpu topology table
    + */
    struct cputopo_arm cpu_topology[NR_CPUS];

    const struct cpumask *cpu_coregroup_mask(int cpu)
    @@ -134,7 +168,7 @@ void init_cpu_topology(void)
    {
    unsigned int cpu;

    - /* init core mask */
    + /* init core mask and power*/
    for_each_possible_cpu(cpu) {
    struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);

    @@ -143,6 +177,8 @@ void init_cpu_topology(void)
    cpu_topo->socket_id = -1;
    cpumask_clear(&cpu_topo->core_sibling);
    cpumask_clear(&cpu_topo->thread_sibling);
    +
    + set_power_scale(cpu, SCHED_POWER_SCALE);
    }
    smp_wmb();
    }
    --
    1.7.9.5


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