diff options
| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-11-07 15:25:12 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-11-11 21:56:07 +0100 |
| commit | c1d51f684c72b5eb2aecbbd47be3a2977a2dc903 (patch) | |
| tree | 4e929d24f9033246e46d08ebf2157d0d438941a1 /drivers/cpuidle/governors/haltpoll.c | |
| parent | 99e98d3fb1008ef7416e16a1fd355cb73a253502 (diff) | |
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 'drivers/cpuidle/governors/haltpoll.c')
| -rw-r--r-- | drivers/cpuidle/governors/haltpoll.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c index 7a703d2e0064..cb2a96eafc02 100644 --- a/drivers/cpuidle/governors/haltpoll.c +++ b/drivers/cpuidle/governors/haltpoll.c @@ -49,7 +49,7 @@ static int haltpoll_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, bool *stop_tick) { - int latency_req = cpuidle_governor_latency_req(dev->cpu); + s64 latency_req = cpuidle_governor_latency_req(dev->cpu); if (!drv->state_count || latency_req == 0) { *stop_tick = false; @@ -75,10 +75,9 @@ static int haltpoll_select(struct cpuidle_driver *drv, return 0; } -static void adjust_poll_limit(struct cpuidle_device *dev, unsigned int block_us) +static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns) { unsigned int val; - u64 block_ns = block_us*NSEC_PER_USEC; /* Grow cpu_halt_poll_us if * cpu_halt_poll_us < block_ns < guest_halt_poll_us @@ -115,7 +114,7 @@ static void haltpoll_reflect(struct cpuidle_device *dev, int index) dev->last_state_idx = index; if (index != 0) - adjust_poll_limit(dev, dev->last_residency); + adjust_poll_limit(dev, dev->last_residency_ns); } /** |