| Message ID | 1510765910-23739-3-git-send-email-pprakash@codeaurora.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 15/11/17 17:11, Prashanth Prakash wrote: > CPU_PM_CPU_IDLE_ENTER_RETENTION skips calling cpu_pm_enter() and > cpu_pm_exit(). By not calling cpu_pm functions in idle entry/exit > paths we can reduce the latency involved in entering and exiting > the low power idle state. > > On ARM64 based Qualcomm server platform we measured below overhead > 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 > > Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org> Acked-by: Sudeep Holla <sudeep.holla@arm.com>
diff --git a/arch/arm64/kernel/cpuidle.c b/arch/arm64/kernel/cpuidle.c index fd69108..f2d1381 100644 --- a/arch/arm64/kernel/cpuidle.c +++ b/arch/arm64/kernel/cpuidle.c @@ -47,6 +47,8 @@ int arm_cpuidle_suspend(int index) #include <acpi/processor.h> +#define ARM64_LPI_IS_RETENTION_STATE(arch_flags) (!(arch_flags)) + int acpi_processor_ffh_lpi_probe(unsigned int cpu) { return arm_cpuidle_init(cpu); @@ -54,6 +56,10 @@ int acpi_processor_ffh_lpi_probe(unsigned int cpu) int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi) { - return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, lpi->index); + if (ARM64_LPI_IS_RETENTION_STATE(lpi->arch_flags)) + return CPU_PM_CPU_IDLE_ENTER_RETENTION(arm_cpuidle_suspend, + lpi->index); + else + return CPU_PM_CPU_IDLE_ENTER(arm_cpuidle_suspend, lpi->index); } #endif
CPU_PM_CPU_IDLE_ENTER_RETENTION skips calling cpu_pm_enter() and cpu_pm_exit(). By not calling cpu_pm functions in idle entry/exit paths we can reduce the latency involved in entering and exiting the low power idle state. On ARM64 based Qualcomm server platform we measured below overhead 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 Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org> --- arch/arm64/kernel/cpuidle.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)