[RFC PATCH V2 0/4] cpuidle: global registration of idle states withper-cpu statistics

From: Trinabh Gupta
Date: Mon Apr 11 2011 - 03:16:35 EST

The core change is to split the cpuidle_device structure into parts
that can be global and parts that has to remain per-cpu. The per-cpu
pieces are mostly generic statistics that can be independent of
current running driver.

* Simplify the cpuidle subsystem framework and have
registration/unregistration done by single cpu.

* Have single copy of cpuidle_states structure and thus reduce
memory consumption.

* Only in very rare cases asymmetric C-states exist which
can be handled within the cpuidle driver. Most architectures
do not have asymmetric C-states.

* References:

The first couple of patches in the series move the statistics accounting
part to withing cpuidle driver; which ensures correctness in updation
of statistics. Moving statistics within cpuidle driver is also required to
make cpuidle_state not writable and thus global. Third patch splits
the per-cpu part out of cpuidle_state structure and the fourth patch
makes the cpuidle_state global. Please refer to
https://lkml.org/lkml/2011/3/25/52 . Version 1 of the series is at

This patch series applies on top of 2.6.38 and is tested on x86 Nehalem
system with multiple ACPI C-States.

To Do:

1. This patch series works only for acpi_idle driver. Changes would
have to be done for other idle drivers i.e. intel_idle, at91_idle_driver,
davinci_idle_driver, kirkwood_idle_driver, omap3_idle_driver.

2. Make ladder governor follow changed API. Currently it works for menu
governor only.



Trinabh Gupta (4):
Single/Global registration of idle states
Split cpuidle_state structure and move per-cpu statistics fields
Remove CPUIDLE_FLAG_IGNORE and dev->prepare()
Move dev->last_residency update to driver enter routine; remove dev->last_state

drivers/acpi/processor_driver.c | 18 ----
drivers/acpi/processor_idle.c | 184 ++++++++++++++++++++++++++++++--------
drivers/cpuidle/cpuidle.c | 80 +++++------------
drivers/cpuidle/driver.c | 26 +++++
drivers/cpuidle/governors/menu.c | 25 +++--
drivers/cpuidle/sysfs.c | 18 ++--
include/linux/cpuidle.h | 49 ++++++----
7 files changed, 247 insertions(+), 153 deletions(-)

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/