From: Martin Schwidefsky <[email protected]>
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 <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: john stultz <[email protected]>
Cc: Daniel Walker <[email protected]>
Signed-off-by: Martin Schwidefsky <[email protected]>
---
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));
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
On Wed, 2009-07-29 at 15:41 +0200, Martin Schwidefsky wrote:
> plain text document attachment (timekeeper-helper.diff)
> From: Martin Schwidefsky <[email protected]>
>
> 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 <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: john stultz <[email protected]>
> Cc: Daniel Walker <[email protected]>
> Signed-off-by: Martin Schwidefsky <[email protected]>
> ---
> 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);
> +
I know it seems nice to have it here, but I think these helpers would be
more reusable in other contexts if they took the cycle_now value as an
argument. Also I'd drop the ntp bit, just to avoid confusing it with
some ntp specific function. So:
timekeeping_get_ns(cycle_t now);
timekeeping_get_ns_raw(cycle_t now);
That way in some situations we don't have to make two accesses to the
hardware if we want to get both values at the same point.
Seem reasonable?
thanks
-john
> + /* 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));
>
On Thu, 30 Jul 2009 14:39:54 -0700
john stultz <[email protected]> wrote:
> On Wed, 2009-07-29 at 15:41 +0200, Martin Schwidefsky wrote:
> > plain text document attachment (timekeeper-helper.diff)
> > From: Martin Schwidefsky <[email protected]>
> >
> > 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 <[email protected]>
> > Cc: Thomas Gleixner <[email protected]>
> > Cc: john stultz <[email protected]>
> > Cc: Daniel Walker <[email protected]>
> > Signed-off-by: Martin Schwidefsky <[email protected]>
> > ---
> > 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);
> > +
>
> I know it seems nice to have it here, but I think these helpers would be
> more reusable in other contexts if they took the cycle_now value as an
> argument. Also I'd drop the ntp bit, just to avoid confusing it with
> some ntp specific function. So:
>
> timekeeping_get_ns(cycle_t now);
> timekeeping_get_ns_raw(cycle_t now);
>
> That way in some situations we don't have to make two accesses to the
> hardware if we want to get both values at the same point.
>
> Seem reasonable?
The new names are fine but if we pull out the ->read call to the
caller we again have a rather strange mix. The caller gets the cycle
value using some clock, the helper uses the value of the timekeeper
clock or the timerkeeper mult/shift. I would like to keep the ->read
call in the helper. Is there a situation where we need both
calculations for the same cycles value? There is none in the current
code as far as I can see.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
On Fri, 2009-07-31 at 09:45 +0200, Martin Schwidefsky wrote:
> On Thu, 30 Jul 2009 14:39:54 -0700
> john stultz <[email protected]> wrote:
>
> > On Wed, 2009-07-29 at 15:41 +0200, Martin Schwidefsky wrote:
> > > plain text document attachment (timekeeper-helper.diff)
> > > From: Martin Schwidefsky <[email protected]>
> > >
> > > 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 <[email protected]>
> > > Cc: Thomas Gleixner <[email protected]>
> > > Cc: john stultz <[email protected]>
> > > Cc: Daniel Walker <[email protected]>
> > > Signed-off-by: Martin Schwidefsky <[email protected]>
> > > ---
> > > 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);
> > > +
> >
> > I know it seems nice to have it here, but I think these helpers would be
> > more reusable in other contexts if they took the cycle_now value as an
> > argument. Also I'd drop the ntp bit, just to avoid confusing it with
> > some ntp specific function. So:
> >
> > timekeeping_get_ns(cycle_t now);
> > timekeeping_get_ns_raw(cycle_t now);
> >
> > That way in some situations we don't have to make two accesses to the
> > hardware if we want to get both values at the same point.
> >
> > Seem reasonable?
>
> The new names are fine but if we pull out the ->read call to the
> caller we again have a rather strange mix. The caller gets the cycle
> value using some clock, the helper uses the value of the timekeeper
> clock or the timerkeeper mult/shift. I would like to keep the ->read
> call in the helper. Is there a situation where we need both
> calculations for the same cycles value? There is none in the current
> code as far as I can see.
One instance: Changing it would allow us to use this code in
timekeeping_forward() as we want to be able to accumulate the current
cycles into xtime and then set cycles_last equal to the read value at
that time. By embedding the read into the timekeeping_read_clock_x() it
avoids us from using the function with any of the management calls. If
you look at the mega-patch I sent out earlier, I think there were a few
uses for such helper functions in update_wall_time and other spots.
Also I have had some discussions with folks that would like to have the
ability to generate multiple CLOCK_ID values at the same "instance".
There isn't a good interface to userland for such a feature, but I'm
hesitant to make it difficult to compute on the kernel side.
thanks
-john