[RFC][patch 11/12] timekeeper read clock helper functions

Martin Schwidefsky
2009-07-29T13:44:33Z

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From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Add timekeeper_read_clock_ntp and timekeeper_read_clock_raw and use
them for getnstimeofday, ktime_get, ktime_get_ts and getrawmonotonic.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
kernel/time/timekeeping.c | 91 +++++++++++++++++++---------------------------
1 file changed, 38 insertions(+), 53 deletions(-)

Index: linux-2.6/kernel/time/timekeeping.c
===================================================================
--- linux-2.6.orig/kernel/time/timekeeping.c
+++ linux-2.6/kernel/time/timekeeping.c
@@ -84,6 +84,40 @@ static void timekeeper_setup_internals(s
timekeeper.shift = clock->shift;
}

+/* Timekeeper helper functions. */
+static inline s64 timekeeper_read_clock_ntp(void)
+{
+ cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
+
+ /* read clocksource: */
+ clock = timekeeper.clock;
+ cycle_now = clock->read(clock);
+
+ /* calculate the delta since the last update_wall_time: */
+ cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
+
+ /* return delta convert to nanoseconds using ntp adjusted mult. */
+ return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
+ timekeeper.shift);
+}
+
+static inline s64 timekeeper_read_clock_raw(void)
+{
+ cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
+
+ /* read clocksource: */
+ clock = timekeeper.clock;
+ cycle_now = clock->read(clock);
+
+ /* calculate the delta since the last update_wall_time: */
+ cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
+
+ /* return delta convert to nanoseconds using ntp adjusted mult. */
+ return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
+}
+
/*
* This read-write spinlock protects us from races in SMP while
* playing with xtime.
@@ -172,8 +206,6 @@ static void timekeeping_forward_now(void
*/
void getnstimeofday(struct timespec *ts)
{
- cycle_t cycle_now, cycle_delta;
- struct clocksource *clock;
unsigned long seq;
s64 nsecs;

@@ -183,17 +215,7 @@ void getnstimeofday(struct timespec *ts)
seq = read_seqbegin(&xtime_lock);

*ts = xtime;
-
- /* read clocksource: */
- clock = timekeeper.clock;
- cycle_now = clock->read(clock);
-
- /* calculate the delta since the last update_wall_time: */
- cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
-
- /* convert to nanoseconds: */
- nsecs = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
- timekeeper.shift);
+ nsecs = timekeeper_read_clock_ntp();

/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();
@@ -207,8 +229,6 @@ EXPORT_SYMBOL(getnstimeofday);

ktime_t ktime_get(void)
{
- cycle_t cycle_now, cycle_delta;
- struct clocksource *clock;
unsigned int seq;
s64 secs, nsecs;

@@ -218,17 +238,7 @@ ktime_t ktime_get(void)
seq = read_seqbegin(&xtime_lock);
secs = xtime.tv_sec + wall_to_monotonic.tv_sec;
nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec;
-
- /* read clocksource: */
- clock = timekeeper.clock;
- cycle_now = clock->read(clock);
-
- /* calculate the delta since the last update_wall_time: */
- cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
-
- /* convert to nanoseconds: */
- nsecs += clocksource_cyc2ns(cycle_delta, timekeeper.mult,
- timekeeper.shift);
+ nsecs += timekeeper_read_clock_ntp();

} while (read_seqretry(&xtime_lock, seq));
/*
@@ -249,8 +259,6 @@ EXPORT_SYMBOL_GPL(ktime_get);
*/
void ktime_get_ts(struct timespec *ts)
{
- cycle_t cycle_now, cycle_delta;
- struct clocksource *clock;
struct timespec tomono;
unsigned int seq;
s64 nsecs;
@@ -261,17 +269,7 @@ void ktime_get_ts(struct timespec *ts)
seq = read_seqbegin(&xtime_lock);
*ts = xtime;
tomono = wall_to_monotonic;
-
- /* read clocksource: */
- clock = timekeeper.clock;
- cycle_now = clock->read(clock);
-
- /* calculate the delta since the last update_wall_time: */
- cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
-
- /* convert to nanoseconds: */
- nsecs = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
- timekeeper.shift);
+ nsecs = timekeeper_read_clock_ntp();

} while (read_seqretry(&xtime_lock, seq));

@@ -433,23 +431,10 @@ void getrawmonotonic(struct timespec *ts
{
unsigned long seq;
s64 nsecs;
- cycle_t cycle_now, cycle_delta;
- struct clocksource *clock;

do {
seq = read_seqbegin(&xtime_lock);
-
- /* read clocksource: */
- clock = timekeeper.clock;
- cycle_now = clock->read(clock);
-
- /* calculate the delta since the last update_wall_time: */
- cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
-
- /* convert to nanoseconds: */
- nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,
- clock->shift);
-
+ nsecs = timekeeper_read_clock_raw();
*ts = raw_time;

} while (read_seqretry(&xtime_lock, seq));