xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

timekeeping: Increase granularity of read_persistent_clock()

Browse Source 
The persistent clock of some architectures (e.g. s390) have a
better granularity than seconds. To reduce the delta between the
host clock and the guest clock in a virtualized system change the 
read_persistent_clock function to return a struct timespec.

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: <20090814134811.013873340@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Martin Schwidefsky
2009-08-14 15:47:31 +02:00
committed by Thomas Gleixner
parent 75c5158f70
commit d4f587c67f
16 changed files with 83 additions and 74 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
arch/s390/kernel/time.c
View File

@@ -182,12 +182,9 @@ static void timing_alert_interrupt(__u16 code)
static void etr_reset(void);
static void stp_reset(void);
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
struct timespec ts;
tod_to_timeval(get_clock() - TOD_UNIX_EPOCH, &ts);
return ts.tv_sec;
tod_to_timeval(get_clock() - TOD_UNIX_EPOCH, ts);
}
static cycle_t read_tod_clock(struct clocksource *cs)
@@ -248,7 +245,6 @@ void __init time_init(void)
{
struct timespec ts;
unsigned long flags;
cycle_t now;
/* Reset time synchronization interfaces. */
etr_reset();
@@ -266,20 +262,10 @@ void __init time_init(void)
panic("Could not register TOD clock source");
/*
* The TOD clock is an accurate clock. The xtime should be
* initialized in a way that the difference between TOD and
* xtime is reasonably small. Too bad that timekeeping_init
* sets xtime.tv_nsec to zero. In addition the clock source
* change from the jiffies clock source to the TOD clock
* source add another error of up to 1/HZ second. The same
* function sets wall_to_monotonic to a value that is too
* small for /proc/uptime to be accurate.
* Reset xtime and wall_to_monotonic to sane values.
* Reset wall_to_monotonic to the initial timestamp created
* in head.S to get a precise value in /proc/uptime.
*/
write_seqlock_irqsave(&xtime_lock, flags);
now = get_clock();
tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime);
clocksource_tod.cycle_last = now;
tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &ts);
set_normalized_timespec(&wall_to_monotonic, -ts.tv_sec, -ts.tv_nsec);
write_sequnlock_irqrestore(&xtime_lock, flags);