Commit 7bc7d637 authored by john stultz's avatar john stultz Committed by Ingo Molnar
Browse files

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: default avatarJohn Stultz <johnstul@us.ibm.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarJohn 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: default avatarIngo Molnar <mingo@elte.hu>
parent a092ff0f

kernel/time.c

+0 −1
Original line number Diff line number Diff line
@@ -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();

}

kernel/time/timekeeping.c

+4 −23
Original line number Diff line number Diff line
@@ -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));

CRA Git | Maintained and supported by SUSTech CRA and CCSE