Subject: [PATCH 0/2]: cpuidle: Introducing cpuidle infrastructure to powerpc.
Date: Wednesday 19th August 2009 12:57:16 UTC (over 8 years ago)
Hi, **** RFC not for inclusion **** "Cpuidle" is a CPU Power Management infrastrusture which helps manage idle CPUs in a clean and efficient manner. The architecture can register its driver (in this case, tpmd_idle driver) so that it subscribes for cpuidle feature. Cpuidle has a set of governors (ladder and menu), which will decide the best idle state to be chosen for the current situation, based on heuristics, and calculates the expected residency time for the current idle state. So based on this, the cpu is put into the right idle state. Currently, cpuidle infrasture is exploited by ACPI to choose between the available ACPI C-states. This patch-set is aimed at enabling cpuidle for powerpc and provides a sample implementation for pseries. Currently, in the pseries_dedicated_idle_sleep(), the processor would poll for a time period, which is called the snooze, and only then it is ceded, which would put the processor in nap state. Cpuidle aims at separating this into 2 different idle states. Based on the expected residency time predicted by the cpuidle governor, the idle state is chosen directly. So, choosing to enter the nap state directly based on the decision made by cpuidle would avoid unnecessary snoozing before entering nap. This patch-set tries to achieve the above objective by introducing a Thermal and Power Management Device module called tpmd_idle in arch/powerpc/platform/pseries/tpmd_idle.c, which implements cpuidle idle loop which would replace the pseries_dedicated_idle_sleep() when cpuidle is enabled. Patches included in this set: PATCH 1/2 - Enable cpuidle for pSeries. PATCH 2/2 - Implement Thermal & Power Management Devices(TPMD) idle module Any feedback on the overall design and idea is immensely valuable. --arun