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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-11-07 17:25:12 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-11-11 23:56:07 +0300 |
| commit | c1d51f684c72b5eb2aecbbd47be3a2977a2dc903 (patch) | |
| tree | 4e929d24f9033246e46d08ebf2157d0d438941a1 /include/linux/cpuidle.h | |
| parent | 99e98d3fb1008ef7416e16a1fd355cb73a253502 (diff) | |
| download | linux-c1d51f684c72b5eb2aecbbd47be3a2977a2dc903.tar.xz | |
cpuidle: Use nanoseconds as the unit of time
Currently, the cpuidle subsystem uses microseconds as the unit of
time which (among other things) causes the idle loop to incur some
integer division overhead for no clear benefit.
In order to allow cpuidle to measure time in nanoseconds, add two
new fields, exit_latency_ns and target_residency_ns, to represent the
exit latency and target residency of an idle state in nanoseconds,
respectively, to struct cpuidle_state and initialize them with the
help of the corresponding values in microseconds provided by drivers.
Additionally, change cpuidle_governor_latency_req() to return the
idle state exit latency constraint in nanoseconds.
Also meeasure idle state residency (last_residency_ns in struct
cpuidle_device and time_ns in struct cpuidle_driver) in nanoseconds
and update the cpuidle core and governors accordingly.
However, the menu governor still computes typical intervals in
microseconds to avoid integer overflows.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Doug Smythies <dsmythies@telus.net>
Tested-by: Doug Smythies <dsmythies@telus.net>
Diffstat (limited to 'include/linux/cpuidle.h')
| -rw-r--r-- | include/linux/cpuidle.h | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index d23a3b1ddcf6..22602747f468 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -35,7 +35,7 @@ struct cpuidle_driver; struct cpuidle_state_usage { unsigned long long disable; unsigned long long usage; - unsigned long long time; /* in US */ + u64 time_ns; unsigned long long above; /* Number of times it's been too deep */ unsigned long long below; /* Number of times it's been too shallow */ #ifdef CONFIG_SUSPEND @@ -48,6 +48,8 @@ struct cpuidle_state { char name[CPUIDLE_NAME_LEN]; char desc[CPUIDLE_DESC_LEN]; + u64 exit_latency_ns; + u64 target_residency_ns; unsigned int flags; unsigned int exit_latency; /* in US */ int power_usage; /* in mW */ @@ -89,7 +91,7 @@ struct cpuidle_device { ktime_t next_hrtimer; int last_state_idx; - int last_residency; + u64 last_residency_ns; u64 poll_limit_ns; struct cpuidle_state_usage states_usage[CPUIDLE_STATE_MAX]; struct cpuidle_state_kobj *kobjs[CPUIDLE_STATE_MAX]; @@ -263,7 +265,7 @@ struct cpuidle_governor { #ifdef CONFIG_CPU_IDLE extern int cpuidle_register_governor(struct cpuidle_governor *gov); -extern int cpuidle_governor_latency_req(unsigned int cpu); +extern s64 cpuidle_governor_latency_req(unsigned int cpu); #else static inline int cpuidle_register_governor(struct cpuidle_governor *gov) {return 0;} |