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ARM64 / cpuidle: Use new cpuidle macro for entering retention state 

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

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>
This commit is contained in:
Prashanth Prakash 2017-11-15 10:11:50 -07:00 committed by Catalin Marinas
parent db50a74d81
commit 8b9951ed7e
1 changed files with 7 additions and 1 deletions
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8
arch/arm64/kernel/cpuidle.c
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@ -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