Commit-ID: 7c032df5570388044b4efda3d9f4d2ffb96a3116
Gitweb: http://git.kernel.org/tip/7c032df5570388044b4efda3d9f4d2ffb96a3116
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Wed, 16 Jul 2014 21:04:10 +0000
Committer: John Stultz <john.stultz@xxxxxxxxxx>
CommitDate: Wed, 23 Jul 2014 10:17:57 -0700
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@xxxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
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 2cb9623..87e0992 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 bfe3ea0..86a9247 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));
--
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