timekeeping: Introduce struct timekeeper
Add struct timekeeper to keep the internal values timekeeping.c needs
in regard to the currently selected clock source. This moves the
timekeeping intervals, xtime_nsec and the ntp error value from struct
clocksource to struct timekeeper. The raw_time is removed from the
clocksource as well. It gets treated like xtime as a global variable.
Eventually xtime raw_time should be moved to struct timekeeper.
[ tglx: minor cleanup ]
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
LKML-Reference: <20090814134809.613209842@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 325a9b6..7af45cb 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -19,6 +19,65 @@
#include <linux/time.h>
#include <linux/tick.h>
+/* Structure holding internal timekeeping values. */
+struct timekeeper {
+ /* Current clocksource used for timekeeping. */
+ struct clocksource *clock;
+
+ /* Number of clock cycles in one NTP interval. */
+ cycle_t cycle_interval;
+ /* Number of clock shifted nano seconds in one NTP interval. */
+ u64 xtime_interval;
+ /* Raw nano seconds accumulated per NTP interval. */
+ u32 raw_interval;
+
+ /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
+ u64 xtime_nsec;
+ /* Difference between accumulated time and NTP time in ntp
+ * shifted nano seconds. */
+ s64 ntp_error;
+};
+
+struct timekeeper timekeeper;
+
+/**
+ * timekeeper_setup_internals - Set up internals to use clocksource clock.
+ *
+ * @clock: Pointer to clocksource.
+ *
+ * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
+ * pair and interval request.
+ *
+ * Unless you're the timekeeping code, you should not be using this!
+ */
+static void timekeeper_setup_internals(struct clocksource *clock)
+{
+ cycle_t interval;
+ u64 tmp;
+
+ timekeeper.clock = clock;
+ clock->cycle_last = clock->read(clock);
+
+ /* Do the ns -> cycle conversion first, using original mult */
+ tmp = NTP_INTERVAL_LENGTH;
+ tmp <<= clock->shift;
+ tmp += clock->mult_orig/2;
+ do_div(tmp, clock->mult_orig);
+ if (tmp == 0)
+ tmp = 1;
+
+ interval = (cycle_t) tmp;
+ timekeeper.cycle_interval = interval;
+
+ /* Go back from cycles -> shifted ns */
+ timekeeper.xtime_interval = (u64) interval * clock->mult;
+ timekeeper.raw_interval =
+ ((u64) interval * clock->mult_orig) >> clock->shift;
+
+ timekeeper.xtime_nsec = 0;
+
+ timekeeper.ntp_error = 0;
+}
/*
* This read-write spinlock protects us from races in SMP while
@@ -46,6 +105,11 @@
struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
static unsigned long total_sleep_time; /* seconds */
+/*
+ * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
+ */
+struct timespec raw_time;
+
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
@@ -56,42 +120,42 @@
timespec_add_ns(&xtime_cache, nsec);
}
-struct clocksource *clock;
-
/* must hold xtime_lock */
void timekeeping_leap_insert(int leapsecond)
{
xtime.tv_sec += leapsecond;
wall_to_monotonic.tv_sec -= leapsecond;
- update_vsyscall(&xtime, clock);
+ update_vsyscall(&xtime, timekeeper.clock);
}
#ifdef CONFIG_GENERIC_TIME
/**
- * clocksource_forward_now - update clock to the current time
+ * timekeeping_forward_now - update clock to the current time
*
* Forward the current clock to update its state since the last call to
* update_wall_time(). This is useful before significant clock changes,
* as it avoids having to deal with this time offset explicitly.
*/
-static void clocksource_forward_now(void)
+static void timekeeping_forward_now(void)
{
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
s64 nsec;
+ clock = timekeeper.clock;
cycle_now = clock->read(clock);
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
clock->cycle_last = cycle_now;
- nsec = cyc2ns(clock, cycle_delta);
+ nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
/* If arch requires, add in gettimeoffset() */
nsec += arch_gettimeoffset();
timespec_add_ns(&xtime, nsec);
- nsec = ((s64)cycle_delta * clock->mult_orig) >> clock->shift;
- clock->raw_time.tv_nsec += nsec;
+ nsec = clocksource_cyc2ns(cycle_delta, clock->mult_orig, clock->shift);
+ timespec_add_ns(&raw_time, nsec);
}
/**
@@ -103,6 +167,7 @@
void getnstimeofday(struct timespec *ts)
{
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
unsigned long seq;
s64 nsecs;
@@ -114,13 +179,15 @@
*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 = cyc2ns(clock, cycle_delta);
+ nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,
+ clock->shift);
/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();
@@ -135,6 +202,7 @@
ktime_t ktime_get(void)
{
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
unsigned int seq;
s64 secs, nsecs;
@@ -146,13 +214,15 @@
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 += cyc2ns(clock, cycle_delta);
+ nsecs += clocksource_cyc2ns(cycle_delta, clock->mult,
+ clock->shift);
} while (read_seqretry(&xtime_lock, seq));
/*
@@ -174,6 +244,7 @@
void ktime_get_ts(struct timespec *ts)
{
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
struct timespec tomono;
unsigned int seq;
s64 nsecs;
@@ -186,13 +257,15 @@
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 = cyc2ns(clock, cycle_delta);
+ nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,
+ clock->shift);
} while (read_seqretry(&xtime_lock, seq));
@@ -233,7 +306,7 @@
write_seqlock_irqsave(&xtime_lock, flags);
- clocksource_forward_now();
+ timekeeping_forward_now();
ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec;
ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec;
@@ -243,10 +316,10 @@
update_xtime_cache(0);
- clock->error = 0;
+ timekeeper.ntp_error = 0;
ntp_clear();
- update_vsyscall(&xtime, clock);
+ update_vsyscall(&xtime, timekeeper.clock);
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -269,10 +342,10 @@
new = clocksource_get_next();
- if (!new || clock == new)
+ if (!new || timekeeper.clock == new)
return;
- clocksource_forward_now();
+ timekeeping_forward_now();
if (new->enable && !new->enable(new))
return;
@@ -284,9 +357,9 @@
*/
new->mult_orig = new->mult;
- new->raw_time = clock->raw_time;
- old = clock;
- clock = new;
+ old = timekeeper.clock;
+ timekeeper_setup_internals(new);
+
/*
* Save mult_orig in mult so that the value can be restored
* regardless if ->enable() updates the value of mult or not.
@@ -295,22 +368,10 @@
if (old->disable)
old->disable(old);
- clock->cycle_last = clock->read(clock);
- clock->error = 0;
- clock->xtime_nsec = 0;
- clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
-
tick_clock_notify();
-
- /*
- * We're holding xtime lock and waking up klogd would deadlock
- * us on enqueue. So no printing!
- printk(KERN_INFO "Time: %s clocksource has been installed.\n",
- clock->name);
- */
}
#else /* GENERIC_TIME */
-static inline void clocksource_forward_now(void) { }
+static inline void timekeeping_forward_now(void) { }
static inline void change_clocksource(void) { }
/**
@@ -380,20 +441,23 @@
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 = ((s64)cycle_delta * clock->mult_orig) >> clock->shift;
+ nsecs = clocksource_cyc2ns(cycle_delta, clock->mult_orig,
+ clock->shift);
- *ts = clock->raw_time;
+ *ts = raw_time;
} while (read_seqretry(&xtime_lock, seq));
@@ -413,7 +477,7 @@
do {
seq = read_seqbegin(&xtime_lock);
- ret = clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
+ ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
} while (read_seqretry(&xtime_lock, seq));
@@ -439,6 +503,7 @@
*/
void __init timekeeping_init(void)
{
+ struct clocksource *clock;
unsigned long flags;
unsigned long sec = read_persistent_clock();
@@ -451,11 +516,13 @@
clock->enable(clock);
/* set mult_orig on enable */
clock->mult_orig = clock->mult;
- clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
- clock->cycle_last = clock->read(clock);
+
+ timekeeper_setup_internals(clock);
xtime.tv_sec = sec;
xtime.tv_nsec = 0;
+ raw_time.tv_sec = 0;
+ raw_time.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
update_xtime_cache(0);
@@ -492,8 +559,8 @@
}
update_xtime_cache(0);
/* re-base the last cycle value */
- clock->cycle_last = clock->read(clock);
- clock->error = 0;
+ timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
+ timekeeper.ntp_error = 0;
timekeeping_suspended = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -514,7 +581,7 @@
timekeeping_suspend_time = read_persistent_clock();
write_seqlock_irqsave(&xtime_lock, flags);
- clocksource_forward_now();
+ timekeeping_forward_now();
timekeeping_suspended = 1;
write_sequnlock_irqrestore(&xtime_lock, flags);
@@ -549,7 +616,7 @@
* If the error is already larger, we look ahead even further
* to compensate for late or lost adjustments.
*/
-static __always_inline int clocksource_bigadjust(s64 error, s64 *interval,
+static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,
s64 *offset)
{
s64 tick_error, i;
@@ -565,7 +632,7 @@
* here. This is tuned so that an error of about 1 msec is adjusted
* within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
*/
- error2 = clock->error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
+ error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
error2 = abs(error2);
for (look_ahead = 0; error2 > 0; look_ahead++)
error2 >>= 2;
@@ -574,8 +641,9 @@
* Now calculate the error in (1 << look_ahead) ticks, but first
* remove the single look ahead already included in the error.
*/
- tick_error = tick_length >> (NTP_SCALE_SHIFT - clock->shift + 1);
- tick_error -= clock->xtime_interval >> 1;
+ tick_error = tick_length >>
+ (NTP_SCALE_SHIFT - timekeeper.clock->shift + 1);
+ tick_error -= timekeeper.xtime_interval >> 1;
error = ((error - tick_error) >> look_ahead) + tick_error;
/* Finally calculate the adjustment shift value. */
@@ -600,18 +668,19 @@
* this is optimized for the most common adjustments of -1,0,1,
* for other values we can do a bit more work.
*/
-static void clocksource_adjust(s64 offset)
+static void timekeeping_adjust(s64 offset)
{
- s64 error, interval = clock->cycle_interval;
+ s64 error, interval = timekeeper.cycle_interval;
int adj;
- error = clock->error >> (NTP_SCALE_SHIFT - clock->shift - 1);
+ error = timekeeper.ntp_error >>
+ (NTP_SCALE_SHIFT - timekeeper.clock->shift - 1);
if (error > interval) {
error >>= 2;
if (likely(error <= interval))
adj = 1;
else
- adj = clocksource_bigadjust(error, &interval, &offset);
+ adj = timekeeping_bigadjust(error, &interval, &offset);
} else if (error < -interval) {
error >>= 2;
if (likely(error >= -interval)) {
@@ -619,15 +688,15 @@
interval = -interval;
offset = -offset;
} else
- adj = clocksource_bigadjust(error, &interval, &offset);
+ adj = timekeeping_bigadjust(error, &interval, &offset);
} else
return;
- clock->mult += adj;
- clock->xtime_interval += interval;
- clock->xtime_nsec -= offset;
- clock->error -= (interval - offset) <<
- (NTP_SCALE_SHIFT - clock->shift);
+ timekeeper.clock->mult += adj;
+ timekeeper.xtime_interval += interval;
+ timekeeper.xtime_nsec -= offset;
+ timekeeper.ntp_error -= (interval - offset) <<
+ (NTP_SCALE_SHIFT - timekeeper.clock->shift);
}
/**
@@ -637,53 +706,59 @@
*/
void update_wall_time(void)
{
+ struct clocksource *clock;
cycle_t offset;
+ s64 nsecs;
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
return;
+ clock = timekeeper.clock;
#ifdef CONFIG_GENERIC_TIME
offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
#else
- offset = clock->cycle_interval;
+ offset = timekeeper.cycle_interval;
#endif
- clock->xtime_nsec = (s64)xtime.tv_nsec << clock->shift;
+ timekeeper.xtime_nsec = (s64)xtime.tv_nsec << clock->shift;
/* normally this loop will run just once, however in the
* case of lost or late ticks, it will accumulate correctly.
*/
- while (offset >= clock->cycle_interval) {
- /* accumulate one interval */
- offset -= clock->cycle_interval;
- clock->cycle_last += clock->cycle_interval;
+ while (offset >= timekeeper.cycle_interval) {
+ u64 nsecps = (u64)NSEC_PER_SEC << clock->shift;
- clock->xtime_nsec += clock->xtime_interval;
- if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
- clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;
+ /* accumulate one interval */
+ offset -= timekeeper.cycle_interval;
+ clock->cycle_last += timekeeper.cycle_interval;
+
+ timekeeper.xtime_nsec += timekeeper.xtime_interval;
+ if (timekeeper.xtime_nsec >= nsecps) {
+ timekeeper.xtime_nsec -= nsecps;
xtime.tv_sec++;
second_overflow();
}
- clock->raw_time.tv_nsec += clock->raw_interval;
- if (clock->raw_time.tv_nsec >= NSEC_PER_SEC) {
- clock->raw_time.tv_nsec -= NSEC_PER_SEC;
- clock->raw_time.tv_sec++;
+ raw_time.tv_nsec += timekeeper.raw_interval;
+ if (raw_time.tv_nsec >= NSEC_PER_SEC) {
+ raw_time.tv_nsec -= NSEC_PER_SEC;
+ raw_time.tv_sec++;
}
/* accumulate error between NTP and clock interval */
- clock->error += tick_length;
- clock->error -= clock->xtime_interval << (NTP_SCALE_SHIFT - clock->shift);
+ timekeeper.ntp_error += tick_length;
+ timekeeper.ntp_error -= timekeeper.xtime_interval <<
+ (NTP_SCALE_SHIFT - clock->shift);
}
/* correct the clock when NTP error is too big */
- clocksource_adjust(offset);
+ timekeeping_adjust(offset);
/*
* Since in the loop above, we accumulate any amount of time
* in xtime_nsec over a second into xtime.tv_sec, its possible for
* xtime_nsec to be fairly small after the loop. Further, if we're
- * slightly speeding the clocksource up in clocksource_adjust(),
+ * slightly speeding the clocksource up in timekeeping_adjust(),
* its possible the required corrective factor to xtime_nsec could
* cause it to underflow.
*
@@ -695,24 +770,26 @@
* We'll correct this error next time through this function, when
* xtime_nsec is not as small.
*/
- if (unlikely((s64)clock->xtime_nsec < 0)) {
- s64 neg = -(s64)clock->xtime_nsec;
- clock->xtime_nsec = 0;
- clock->error += neg << (NTP_SCALE_SHIFT - clock->shift);
+ if (unlikely((s64)timekeeper.xtime_nsec < 0)) {
+ s64 neg = -(s64)timekeeper.xtime_nsec;
+ timekeeper.xtime_nsec = 0;
+ timekeeper.ntp_error += neg << (NTP_SCALE_SHIFT - clock->shift);
}
/* store full nanoseconds into xtime after rounding it up and
* add the remainder to the error difference.
*/
- xtime.tv_nsec = ((s64)clock->xtime_nsec >> clock->shift) + 1;
- clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
- clock->error += clock->xtime_nsec << (NTP_SCALE_SHIFT - clock->shift);
+ xtime.tv_nsec = ((s64)timekeeper.xtime_nsec >> clock->shift) + 1;
+ timekeeper.xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
+ timekeeper.ntp_error += timekeeper.xtime_nsec <<
+ (NTP_SCALE_SHIFT - clock->shift);
- update_xtime_cache(cyc2ns(clock, offset));
+ nsecs = clocksource_cyc2ns(offset, clock->mult, clock->shift);
+ update_xtime_cache(nsecs);
/* check to see if there is a new clocksource to use */
change_clocksource();
- update_vsyscall(&xtime, clock);
+ update_vsyscall(&xtime, timekeeper.clock);
}
/**