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author | Prashanth Prakash <pprakash@codeaurora.org> | 2017-11-15 20:11:49 +0300 |
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committer | Catalin Marinas <catalin.marinas@arm.com> | 2018-01-02 16:48:55 +0300 |
commit | db50a74d8193944dd1ee488fd2a813a364fbbaa7 (patch) | |
tree | d67d11acbee21cbc202701cba4150ccb2b659a20 /arch/arm64/kernel/cpuidle.c | |
parent | 1f911c3a1140e1668e68791fb6dd07757e2f3956 (diff) | |
download | linux-db50a74d8193944dd1ee488fd2a813a364fbbaa7.tar.xz |
cpuidle: Add new macro to enter a retention idle state
If a CPU is entering a low power idle state where it doesn't lose any
context, then there is no need to call cpu_pm_enter()/cpu_pm_exit().
Add a new macro(CPU_PM_CPU_IDLE_ENTER_RETENTION) to be used by cpuidle
drivers when they are entering retention state. By not calling
cpu_pm_enter and cpu_pm_exit we reduce the latency involved in
entering and exiting the retention idle states.
CPU_PM_CPU_IDLE_ENTER_RETENTION assumes that no state is lost and
hence CPU PM notifiers will not be called. We may need a broader
change if we need to support partial retention states effeciently.
On ARM64 based Qualcomm Server Platform we measured below overhead for
for calling cpu_pm_enter and cpu_pm_exit for retention states.
workload: stress --hdd #CPUs --hdd-bytes 32M -t 30
Average overhead of cpu_pm_enter - 1.2us
Average overhead of cpu_pm_exit - 3.1us
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/cpuidle.c')
0 files changed, 0 insertions, 0 deletions