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time: Remove xtime_cache 

With the prior logarithmic time accumulation patch, xtime will now
always be within one "tick" of the current time, instead of
possibly half a second off.

This removes the need for the xtime_cache value, which always
stored the time at the last interrupt, so this patch cleans that up
removing the xtime_cache related code.

This is a bit simpler, but still could use some wider testing.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: John Kacur <jkacur@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <1254525855.7741.95.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
john stultz 2009-10-02 16:24:15 -07:00 committed by Ingo Molnar
parent a092ff0f90
commit 7bc7d63745
2 changed files with 4 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
kernel/time.c
View File

@ -136,7 +136,6 @@ static inline void warp_clock(void)
write_seqlock_irq(&xtime_lock);
wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
xtime.tv_sec += sys_tz.tz_minuteswest * 60;
update_xtime_cache(0);
write_sequnlock_irq(&xtime_lock);
clock_was_set();
}

27
kernel/time/timekeeping.c
View File

@ -164,13 +164,6 @@ 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)
{
@ -331,8 +324,6 @@ int do_settimeofday(struct timespec *tv)
xtime = *tv;
update_xtime_cache(0);
timekeeper.ntp_error = 0;
ntp_clear();
@ -547,7 +538,6 @@ 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);
@ -581,7 +571,6 @@ 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;
@ -721,7 +710,6 @@ static void timekeeping_adjust(s64 offset)
timekeeper.ntp_error_shift;
}
/**
* logarithmic_accumulation - shifted accumulation of cycles
*
@ -765,7 +753,6 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
return offset;
}
/**
* update_wall_time - Uses the current clocksource to increment the wall time
*
@ -775,7 +762,6 @@ void update_wall_time(void)
{
struct clocksource *clock;
cycle_t offset;
u64 nsecs;
int shift = 0, maxshift;
/* Make sure we're fully resumed: */
@ -841,9 +827,6 @@ 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);
}
@ -880,13 +863,13 @@ 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)
@ -896,8 +879,7 @@ 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;
@ -911,8 +893,7 @@ 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));