On 13 June 2012 10:50, Jean Pihet jean.pihet@newoldbits.com wrote:
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?
When several cores are idle, one core runs the load balance for all idle cores. The update of the cpu_power can be done during rebalance and arch_scale_freq_power can be called by CPU0 for updating the cpu_power of CPU1.
I was probably not clear enough in my first explanation. I will reword the comment
Regards, Vincent
Regards, Jean