#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/perf_event.h>
+#include <asm/trace.h>
#include <asm/io.h>
#include <asm/processor.h>
struct clock_event_device *evt = &decrementer->event;
u64 now;
+ trace_timer_interrupt_entry(regs);
+
/* Ensure a positive value is written to the decrementer, or else
* some CPUs will continuue to take decrementer exceptions */
set_dec(DECREMENTER_MAX);
now = decrementer->next_tb - now;
if (now <= DECREMENTER_MAX)
set_dec((int)now);
+ trace_timer_interrupt_exit(regs);
return;
}
old_regs = set_irq_regs(regs);
irq_exit();
set_irq_regs(old_regs);
+
+ trace_timer_interrupt_exit(regs);
}
void wakeup_decrementer(void)
return (cycle_t)get_tb();
}
- void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
+ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock,
+ u32 mult)
{
u64 t2x, stamp_xsec;
/* XXX this assumes clock->shift == 22 */
/* 4611686018 ~= 2^(20+64-22) / 1e9 */
- t2x = (u64) clock->mult * 4611686018ULL;
+ t2x = (u64) mult * 4611686018ULL;
stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
do_div(stamp_xsec, 1000000000);
stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
*dec = decrementer_clockevent;
dec->cpumask = cpumask_of(cpu);
- printk(KERN_DEBUG "clockevent: %s mult[%lx] shift[%d] cpu[%d]\n",
+ printk(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
dec->name, dec->mult, dec->shift, cpu);
clockevents_register_device(dec);
* subtraction of non 64 bit counters
* @mult: cycle to nanosecond multiplier
* @shift: cycle to nanosecond divisor (power of two)
+ * @max_idle_ns: max idle time permitted by the clocksource (nsecs)
* @flags: flags describing special properties
* @vread: vsyscall based read
* @resume: resume function for the clocksource, if necessary
cycle_t mask;
u32 mult;
u32 shift;
+ u64 max_idle_ns;
unsigned long flags;
cycle_t (*vread)(void);
void (*resume)(void);
extern struct clocksource * __init __weak clocksource_default_clock(void);
extern void clocksource_mark_unstable(struct clocksource *cs);
+extern void
+clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
+
+static inline void
+clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
+{
+ return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
+ NSEC_PER_SEC, minsec);
+}
+
#ifdef CONFIG_GENERIC_TIME_VSYSCALL
- extern void update_vsyscall(struct timespec *ts, struct clocksource *c);
+ extern void
+ update_vsyscall(struct timespec *ts, struct clocksource *c, u32 mult);
extern void update_vsyscall_tz(void);
#else
- static inline void update_vsyscall(struct timespec *ts, struct clocksource *c)
+ static inline void
+ update_vsyscall(struct timespec *ts, struct clocksource *c, u32 mult)
{
}
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
-static struct timespec xtime_cache __attribute__ ((aligned (16)));
-void update_xtime_cache(u64 nsec)
-{
- xtime_cache = xtime;
- timespec_add_ns(&xtime_cache, nsec);
-}
-
/* must hold xtime_lock */
void timekeeping_leap_insert(int leapsecond)
{
xtime.tv_sec += leapsecond;
wall_to_monotonic.tv_sec -= leapsecond;
- update_vsyscall(&xtime, timekeeper.clock);
+ update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
}
#ifdef CONFIG_GENERIC_TIME
xtime = *tv;
- update_xtime_cache(0);
-
timekeeper.ntp_error = 0;
ntp_clear();
- update_vsyscall(&xtime, timekeeper.clock);
+ update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
write_sequnlock_irqrestore(&xtime_lock, flags);
return ret;
}
+/**
+ * timekeeping_max_deferment - Returns max time the clocksource can be deferred
+ *
+ * Caller must observe xtime_lock via read_seqbegin/read_seqretry to
+ * ensure that the clocksource does not change!
+ */
+u64 timekeeping_max_deferment(void)
+{
+ return timekeeper.clock->max_idle_ns;
+}
+
/**
* read_persistent_clock - Return time from the persistent clock.
*
}
set_normalized_timespec(&wall_to_monotonic,
-boot.tv_sec, -boot.tv_nsec);
- update_xtime_cache(0);
total_sleep_time.tv_sec = 0;
total_sleep_time.tv_nsec = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
wall_to_monotonic = timespec_sub(wall_to_monotonic, ts);
total_sleep_time = timespec_add_safe(total_sleep_time, ts);
}
- update_xtime_cache(0);
/* re-base the last cycle value */
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
timekeeper.ntp_error = 0;
timekeeper.ntp_error_shift;
}
+/**
+ * logarithmic_accumulation - shifted accumulation of cycles
+ *
+ * This functions accumulates a shifted interval of cycles into
+ * into a shifted interval nanoseconds. Allows for O(log) accumulation
+ * loop.
+ *
+ * Returns the unconsumed cycles.
+ */
+static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
+{
+ u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
+
+ /* If the offset is smaller then a shifted interval, do nothing */
+ if (offset < timekeeper.cycle_interval<<shift)
+ return offset;
+
+ /* Accumulate one shifted interval */
+ offset -= timekeeper.cycle_interval << shift;
+ timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
+
+ timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
+ while (timekeeper.xtime_nsec >= nsecps) {
+ timekeeper.xtime_nsec -= nsecps;
+ xtime.tv_sec++;
+ second_overflow();
+ }
+
+ /* Accumulate into raw time */
+ raw_time.tv_nsec += timekeeper.raw_interval << shift;;
+ while (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 */
+ timekeeper.ntp_error += tick_length << shift;
+ timekeeper.ntp_error -= timekeeper.xtime_interval <<
+ (timekeeper.ntp_error_shift + shift);
+
+ return offset;
+}
+
/**
* update_wall_time - Uses the current clocksource to increment the wall time
*
{
struct clocksource *clock;
cycle_t offset;
- u64 nsecs;
+ int shift = 0, maxshift;
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
#endif
timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift;
- /* normally this loop will run just once, however in the
- * case of lost or late ticks, it will accumulate correctly.
+ /*
+ * With NO_HZ we may have to accumulate many cycle_intervals
+ * (think "ticks") worth of time at once. To do this efficiently,
+ * we calculate the largest doubling multiple of cycle_intervals
+ * that is smaller then the offset. We then accumulate that
+ * chunk in one go, and then try to consume the next smaller
+ * doubled multiple.
*/
+ shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
+ shift = max(0, shift);
+ /* Bound shift to one less then what overflows tick_length */
+ maxshift = (8*sizeof(tick_length) - (ilog2(tick_length)+1)) - 1;
+ shift = min(shift, maxshift);
while (offset >= timekeeper.cycle_interval) {
- u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.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();
- }
-
- 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 */
- timekeeper.ntp_error += tick_length;
- timekeeper.ntp_error -= timekeeper.xtime_interval <<
- timekeeper.ntp_error_shift;
+ offset = logarithmic_accumulation(offset, shift);
+ shift--;
}
/* correct the clock when NTP error is too big */
timekeeper.ntp_error += timekeeper.xtime_nsec <<
timekeeper.ntp_error_shift;
- nsecs = clocksource_cyc2ns(offset, timekeeper.mult, timekeeper.shift);
- update_xtime_cache(nsecs);
-
/* check to see if there is a new clocksource to use */
- update_vsyscall(&xtime, timekeeper.clock);
+ update_vsyscall(&xtime, timekeeper.clock, timekeeper.mult);
}
/**
unsigned long get_seconds(void)
{
- return xtime_cache.tv_sec;
+ return xtime.tv_sec;
}
EXPORT_SYMBOL(get_seconds);
struct timespec __current_kernel_time(void)
{
- return xtime_cache;
+ return xtime;
}
struct timespec current_kernel_time(void)
do {
seq = read_seqbegin(&xtime_lock);
-
- now = xtime_cache;
+ now = xtime;
} while (read_seqretry(&xtime_lock, seq));
return now;
do {
seq = read_seqbegin(&xtime_lock);
-
- now = xtime_cache;
+ now = xtime;
mono = wall_to_monotonic;
} while (read_seqretry(&xtime_lock, seq));
projects / linux-2.6-block.git / commitdiff