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timekeeping: Provide internal ktime_t based data 

The ktime_t based interfaces are used a lot in performance critical
code pathes. Add ktime_t based data so the interfaces don't have to
convert from the xtime/timespec based data.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Thomas Gleixner 2014-07-16 21:04:10 +00:00 committed by John Stultz
parent f111adfdd7
commit 7c032df557
2 changed files with 25 additions and 0 deletions
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3
include/linux/timekeeper_internal.h
View File

@ -36,6 +36,9 @@ struct timekeeper {
/* Clock shifted nano seconds */
u64 xtime_nsec;
/* Monotonic base time */
ktime_t base_mono;
/* Current CLOCK_REALTIME time in seconds */
u64 xtime_sec;
/* CLOCK_REALTIME to CLOCK_MONOTONIC offset */

22
kernel/time/timekeeping.c
View File

@ -291,6 +291,26 @@ int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
}
EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
/*
* Update the ktime_t based scalar nsec members of the timekeeper
*/
static inline void tk_update_ktime_data(struct timekeeper *tk)
{
s64 nsec;
/*
* The xtime based monotonic readout is:
* nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
* The ktime based monotonic readout is:
* nsec = base_mono + now();
* ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
*/
nsec = (s64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
nsec *= NSEC_PER_SEC;
nsec += tk->wall_to_monotonic.tv_nsec;
tk->base_mono = ns_to_ktime(nsec);
}
/* must hold timekeeper_lock */
static void timekeeping_update(struct timekeeper *tk, unsigned int action)
{
@ -301,6 +321,8 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action)
update_vsyscall(tk);
update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
tk_update_ktime_data(tk);
if (action & TK_MIRROR)
memcpy(&shadow_timekeeper, &tk_core.timekeeper,
sizeof(tk_core.timekeeper));