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| author |   Prashanth Prakash <pprakash@codeaurora.org> | 2017-11-15 10:11:49 -0700 |
|---|---|---|
| committer |   Catalin Marinas <catalin.marinas@arm.com> | 2018-01-02 13:48:55 +0000 |
| commit | db50a74d8193944dd1ee488fd2a813a364fbbaa7 (patch) | |
| tree | d67d11acbee21cbc202701cba4150ccb2b659a20 /include/linux/cpuidle.h | |
| parent | Merge branch 'for-next/52-bit-pa' into for-next/core (diff) | |
| download | linux-dev-db50a74d8193944dd1ee488fd2a813a364fbbaa7.tar.xz linux-dev-db50a74d8193944dd1ee488fd2a813a364fbbaa7.zip | |
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 'include/linux/cpuidle.h')
| -rw-r--r-- | include/linux/cpuidle.h | 40 |
1 files changed, 24 insertions, 16 deletions
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index 8f7788d23b57..871f9e21810c 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -257,22 +257,30 @@ static inline int cpuidle_register_governor(struct cpuidle_governor *gov) {return 0;} #endif -#define CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx) \ -({ \ - int __ret; \ - \ - if (!idx) { \ - cpu_do_idle(); \ - return idx; \ - } \ - \ - __ret = cpu_pm_enter(); \ - if (!__ret) { \ - __ret = low_level_idle_enter(idx); \ - cpu_pm_exit(); \ - } \ - \ - __ret ? -1 : idx; \ +#define __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, is_retention) \ +({ \ + int __ret = 0; \ + \ + if (!idx) { \ + cpu_do_idle(); \ + return idx; \ + } \ + \ + if (!is_retention) \ + __ret = cpu_pm_enter(); \ + if (!__ret) { \ + __ret = low_level_idle_enter(idx); \ + if (!is_retention) \ + cpu_pm_exit(); \ + } \ + \ + __ret ? -1 : idx; \ }) +#define CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx) \ + __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, 0) + +#define CPU_PM_CPU_IDLE_ENTER_RETENTION(low_level_idle_enter, idx) \ + __CPU_PM_CPU_IDLE_ENTER(low_level_idle_enter, idx, 1) + #endif /* _LINUX_CPUIDLE_H */ |