diff options
| author | Vincent Guittot <vincent.guittot@linaro.org> | 2018-12-14 15:22:25 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2018-12-19 10:31:50 +0100 |
| commit | 8234f6734c5d74ac794e5517437f51c57d65f865 (patch) | |
| tree | 3aadac1af824e3071283ca9bd008eaa5e0980eb0 /include/linux/pm.h | |
| parent | 7566ec393f4161572ba6f11ad5171fd5d59b0fbd (diff) | |
PM-runtime: Switch autosuspend over to using hrtimers
PM-runtime uses the timer infrastructure for autosuspend. This implies
that the minimum time before autosuspending a device is in the range
of 1 tick included to 2 ticks excluded
-On arm64 this means between 4ms and 8ms with default jiffies
configuration
-And on arm, it is between 10ms and 20ms
These values are quite high for embedded systems which sometimes want
the duration to be in the range of 1 ms.
It is possible to switch autosuspend over to using hrtimers to get
finer granularity for short durations and take advantage of slack to
retain some margins and get long timeouts with minimum wakeups.
On an arm64 platform that uses 1ms for autosuspending timeout of its
GPU, idle power is reduced by 10% with hrtimer.
The latency impact on arm64 hikey octo cores is:
- mark_last_busy: from 1.11 us to 1.25 us
- rpm_suspend: from 15.54 us to 15.38 us
[Only the code path of rpm_suspend() that starts hrtimer has been
measured.]
arm64 image (arm64 default defconfig) decreases by around 3KB
with following details:
$ size vmlinux-timer
text data bss dec hex filename
12034646 6869268 386840 19290754 1265a82 vmlinux
$ size vmlinux-hrtimer
text data bss dec hex filename
12030550 6870164 387032 19287746 1264ec2 vmlinux
The latency impact on arm 32bits snowball dual cores is :
- mark_last_busy: from 0.31 us usec to 0.77 us
- rpm_suspend: from 6.83 us to 6.67 usec
The increase of the image for snowball platform that I used for
testing performance impact, is neglictable (244B).
$ size vmlinux-timer
text data bss dec hex filename
7157961 2119580 264120 9541661 91981d build-ux500/vmlinux
size vmlinux-hrtimer
text data bss dec hex filename
7157773 2119884 264248 9541905 919911 vmlinux-hrtimer
And arm 32bits image (multi_v7_defconfig) increases by around 1.7KB
with following details:
$ size vmlinux-timer
text data bss dec hex filename
13304443 6803420 402768 20510631 138f7a7 vmlinux
$ size vmlinux-hrtimer
text data bss dec hex filename
13304299 6805276 402768 20512343 138fe57 vmlinux
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'include/linux/pm.h')
| -rw-r--r-- | include/linux/pm.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/pm.h b/include/linux/pm.h index e723b78d8357..0bd9de116826 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -26,6 +26,7 @@ #include <linux/spinlock.h> #include <linux/wait.h> #include <linux/timer.h> +#include <linux/hrtimer.h> #include <linux/completion.h> /* @@ -608,7 +609,7 @@ struct dev_pm_info { unsigned int should_wakeup:1; #endif #ifdef CONFIG_PM - struct timer_list suspend_timer; + struct hrtimer suspend_timer; unsigned long timer_expires; struct work_struct work; wait_queue_head_t wait_queue; @@ -631,7 +632,7 @@ struct dev_pm_info { enum rpm_status runtime_status; int runtime_error; int autosuspend_delay; - unsigned long last_busy; + u64 last_busy; unsigned long active_jiffies; unsigned long suspended_jiffies; unsigned long accounting_timestamp; |