diff options
| -rw-r--r-- | include/linux/energy_model.h | 16 | ||||
| -rw-r--r-- | kernel/power/energy_model.c | 4 |
2 files changed, 19 insertions, 1 deletions
diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h index 3f221dbf5f95..1834752c5617 100644 --- a/include/linux/energy_model.h +++ b/include/linux/energy_model.h @@ -53,6 +53,22 @@ struct em_perf_domain { #ifdef CONFIG_ENERGY_MODEL #define EM_MAX_POWER 0xFFFF +/* + * Increase resolution of energy estimation calculations for 64-bit + * architectures. The extra resolution improves decision made by EAS for the + * task placement when two Performance Domains might provide similar energy + * estimation values (w/o better resolution the values could be equal). + * + * We increase resolution only if we have enough bits to allow this increased + * resolution (i.e. 64-bit). The costs for increasing resolution when 32-bit + * are pretty high and the returns do not justify the increased costs. + */ +#ifdef CONFIG_64BIT +#define em_scale_power(p) ((p) * 1000) +#else +#define em_scale_power(p) (p) +#endif + struct em_data_callback { /** * active_power() - Provide power at the next performance state of diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index 0f4530b3a8cd..a332ccd829e2 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -170,7 +170,9 @@ static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd, /* Compute the cost of each performance state. */ fmax = (u64) table[nr_states - 1].frequency; for (i = 0; i < nr_states; i++) { - table[i].cost = div64_u64(fmax * table[i].power, + unsigned long power_res = em_scale_power(table[i].power); + + table[i].cost = div64_u64(fmax * power_res, table[i].frequency); } |