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Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  timers, init: Limit the number of per cpu calibration bootup messages
  posix-cpu-timers: optimize and document timer_create callback
  clockevents: Add missing include to pacify sparse
  x86: vmiclock: Fix printk format
  x86: Fix printk format due to variable type change
  sparc: fix printk for change of variable type
  clocksource/events: Fix fallout of generic code changes
  nohz: Allow 32-bit machines to sleep for more than 2.15 seconds
  nohz: Track last do_timer() cpu
  nohz: Prevent clocksource wrapping during idle
  nohz: Type cast printk argument
  mips: Use generic mult/shift factor calculation for clocks
  clocksource: Provide a generic mult/shift factor calculation
  clockevents: Use u32 for mult and shift factors
  nohz: Introduce arch_needs_cpu
  nohz: Reuse ktime in sub-functions of tick_check_idle.
  time: Remove xtime_cache
  time: Implement logarithmic time accumulation
This commit is contained in:
Linus Torvalds
2009-12-08 19:27:08 -08:00
parent 849e8dea09 feae3203d7
commit 60d8ce2cd6
26 changed files with 353 additions and 178 deletions
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119
kernel/time/timekeeping.c
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@@ -165,13 +165,6 @@ struct timespec raw_time;
/* 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)
{
@@ -332,8 +325,6 @@ int do_settimeofday(struct timespec *tv)
xtime = *tv;
update_xtime_cache(0);
timekeeper.ntp_error = 0;
ntp_clear();
@@ -487,6 +478,17 @@ int timekeeping_valid_for_hres(void)
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.
*
@@ -548,7 +550,6 @@ void __init timekeeping_init(void)
}
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);
@@ -582,7 +583,6 @@ static int timekeeping_resume(struct sys_device *dev)
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;
@@ -722,6 +722,49 @@ static void timekeeping_adjust(s64 offset)
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
*
@@ -731,7 +774,7 @@ void update_wall_time(void)
{
struct clocksource *clock;
cycle_t offset;
u64 nsecs;
int shift = 0, maxshift;
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
@@ -745,33 +788,22 @@ void update_wall_time(void)
#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 */
@@ -807,9 +839,6 @@ void update_wall_time(void)
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);
}
@@ -846,13 +875,13 @@ void monotonic_to_bootbased(struct timespec *ts)
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)
@@ -862,8 +891,7 @@ 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;
@@ -877,8 +905,7 @@ struct timespec get_monotonic_coarse(void)
do {
seq = read_seqbegin(&xtime_lock);
now = xtime_cache;
now = xtime;
mono = wall_to_monotonic;
} while (read_seqretry(&xtime_lock, seq));