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authorThomas Gleixner <tglx@linutronix.de>2014-07-16 21:04:10 +0000
committerJohn Stultz <john.stultz@linaro.org>2014-07-23 10:17:57 -0700
commit7c032df5570388044b4efda3d9f4d2ffb96a3116 (patch)
treeab8242028af30b3b914b8c33cdfe30fb2feca6c2 /kernel
parentf111adfdd7ff7d9fe54b6efa440b80824984749c (diff)
downloadlinux-7c032df5570388044b4efda3d9f4d2ffb96a3116.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/timekeeping.c22
1 files changed, 22 insertions, 0 deletions
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));