On Tue, Jul 07, 2015 at 07:24:11PM +0100, Morten Rasmussen wrote: > cpuidle associates all idle-states with each cpu while the energy model > associates them with the sched_group covering the cpus coordinating > entry to the idle-state. To look up the idle-state power consumption in > the energy model it is therefore necessary to translate from cpuidle > idle-state index to energy model index. For this purpose it is helpful > to know how many idle-states that are listed in lower level sched_groups > (in struct sched_group_energy). > > Example: ARMv8 big.LITTLE JUNO (Cortex A57, A53) idle-states: > Idle-state cpuidle Energy model table indices > index per-cpu sg per-cluster sg > WFI 0 0 (0) > Core power-down 1 1 0* > Cluster power-down 2 (1) 1 > > For per-cpu sgs no translation is required. If cpuidle reports state > index 0 or 1, the cpu is in WFI or core power-down, respectively. We can > look the idle-power up directly in the sg energy model table.
OK.. > Idle-state > cluster power-down, is represented in the per-cluster sg energy model > table as index 1. Index 0* is reserved for cluster power consumption > when the cpus all are in state 0 or 1, but cpuidle decided not to go for > cluster power-down. 0* is not an integer. > Given the index from cpuidle we can compute the > correct index in the energy model tables for the sgs at each level if we > know how many states are in the tables in the child sgs. The actual > translation is implemented in a later patch. And you've lost me... I've looked at that later patch (its the next one) and I cannot say I'm less confused. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
