From 7c032df5570388044b4efda3d9f4d2ffb96a3116 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 16 Jul 2014 21:04:10 +0000 Subject: [PATCH] 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 Signed-off-by: John Stultz --- include/linux/timekeeper_internal.h | 3 +++ kernel/time/timekeeping.c | 22 ++++++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h index 2cb96235c249..87e0992564f2 100644 --- a/include/linux/timekeeper_internal.h +++ b/include/linux/timekeeper_internal.h @@ -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 */ diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index bfe3ea09afc9..86a92476c027 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -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)); -- 2.20.1