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timekeeping: Increase granularity of read_persistent_clock()

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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/m68knommu/kernel/time.c
View File

@ -72,9 +72,10 @@ static unsigned long read_rtc_mmss(void)
return mktime(year, mon, day, hour, min, sec);;
}
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
return read_rtc_mmss();
ts->tv_sec = read_rtc_mmss();
ts->tv_nsec = 0;
}
int update_persistent_clock(struct timespec now)

5
arch/mips/dec/time.c
View File

@ -18,7 +18,7 @@
#include <asm/dec/ioasic.h>
#include <asm/dec/machtype.h>
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
unsigned int year, mon, day, hour, min, sec, real_year;
unsigned long flags;
@ -53,7 +53,8 @@ unsigned long read_persistent_clock(void)
year += real_year - 72 + 2000;
return mktime(year, mon, day, hour, min, sec);
ts->tv_sec = mktime(year, mon, day, hour, min, sec);
ts->tv_nsec = 0;
}
/*

5
arch/mips/lasat/ds1603.c
View File

@ -135,7 +135,7 @@ static void rtc_end_op(void)
lasat_ndelay(1000);
}
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
unsigned long word;
unsigned long flags;
@ -147,7 +147,8 @@ unsigned long read_persistent_clock(void)
rtc_end_op();
spin_unlock_irqrestore(&rtc_lock, flags);
return word;
ts->tv_sec = word;
ts->tv_nsec = 0;
}
int rtc_mips_set_mmss(unsigned long time)

8
arch/mips/lasat/sysctl.c
View File

@ -92,10 +92,12 @@ static int rtctmp;
int proc_dolasatrtc(ctl_table *table, int write, struct file *filp,
void *buffer, size_t *lenp, loff_t *ppos)
{
struct timespec ts;
int r;
if (!write) {
rtctmp = read_persistent_clock();
read_persistent_clock(&ts);
rtctmp = ts.tv_sec;
/* check for time < 0 and set to 0 */
if (rtctmp < 0)
rtctmp = 0;
@ -134,9 +136,11 @@ int sysctl_lasat_rtc(ctl_table *table,
void *oldval, size_t *oldlenp,
void *newval, size_t newlen)
{
struct timespec ts;
int r;
rtctmp = read_persistent_clock();
read_persistent_clock(&ts);
rtctmp = ts.tv_sec;
if (rtctmp < 0)
rtctmp = 0;
r = sysctl_intvec(table, oldval, oldlenp, newval, newlen);

5
arch/mips/lemote/lm2e/setup.c
View File

@ -54,9 +54,10 @@ void __init plat_time_init(void)
mips_hpt_frequency = cpu_clock_freq / 2;
}
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
return mc146818_get_cmos_time();
ts->tv_sec = mc146818_get_cmos_time();
ts->tv_nsec = 0;
}
void (*__wbflush)(void);

5
arch/mips/mti-malta/malta-time.c
View File

@ -100,9 +100,10 @@ static unsigned int __init estimate_cpu_frequency(void)
return count;
}
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
return mc146818_get_cmos_time();
ts->tv_sec = mc146818_get_cmos_time();
ts->tv_nsec = 0;
}
static void __init plat_perf_setup(void)

5
arch/mips/pmc-sierra/yosemite/setup.c
View File

@ -70,7 +70,7 @@ void __init bus_error_init(void)
}
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
unsigned int year, month, day, hour, min, sec;
unsigned long flags;
@ -92,7 +92,8 @@ unsigned long read_persistent_clock(void)
m48t37_base->control = 0x00;
spin_unlock_irqrestore(&rtc_lock, flags);
return mktime(year, month, day, hour, min, sec);
ts->tv_sec = mktime(year, month, day, hour, min, sec);
ts->tv_nsec = 0;
}
int rtc_mips_set_time(unsigned long tim)

15
arch/mips/sibyte/swarm/setup.c
View File

@ -87,19 +87,26 @@ enum swarm_rtc_type {
enum swarm_rtc_type swarm_rtc_type;
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
unsigned long sec;
switch (swarm_rtc_type) {
case RTC_XICOR:
return xicor_get_time();
sec = xicor_get_time();
break;
case RTC_M4LT81:
return m41t81_get_time();
sec = m41t81_get_time();
break;
case RTC_NONE:
default:
return mktime(2000, 1, 1, 0, 0, 0);
sec = mktime(2000, 1, 1, 0, 0, 0);
break;
}
ts->tv_sec = sec;
tv->tv_nsec = 0;
}
int rtc_mips_set_time(unsigned long sec)

5
arch/mips/sni/time.c
View File

@ -182,7 +182,8 @@ void __init plat_time_init(void)
setup_pit_timer();
}
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
return -1;
ts->tv_sec = -1;
ts->tv_nsec = 0;
}

7
arch/powerpc/kernel/time.c
View File

@ -769,7 +769,7 @@ int update_persistent_clock(struct timespec now)
return ppc_md.set_rtc_time(&tm);
}
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
struct rtc_time tm;
static int first = 1;
@ -787,8 +787,9 @@ unsigned long read_persistent_clock(void)
if (!ppc_md.get_rtc_time)
return 0;
ppc_md.get_rtc_time(&tm);
return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
tm.tm_hour, tm.tm_min, tm.tm_sec);
ts->tv_sec = mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
tm.tm_hour, tm.tm_min, tm.tm_sec);
ts->tv_nsec = 0;
}
/* clocksource code */

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);

6
arch/sh/kernel/time.c
View File

@ -39,11 +39,9 @@ void (*rtc_sh_get_time)(struct timespec *) = null_rtc_get_time;
int (*rtc_sh_set_time)(const time_t) = null_rtc_set_time;
#ifdef CONFIG_GENERIC_CMOS_UPDATE
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
struct timespec tv;
rtc_sh_get_time(&tv);
return tv.tv_sec;
rtc_sh_get_time(&ts);
}
int update_persistent_clock(struct timespec now)

5
arch/x86/kernel/rtc.c
View File

@ -178,7 +178,7 @@ static int set_rtc_mmss(unsigned long nowtime)
}
/* not static: needed by APM */
unsigned long read_persistent_clock(void)
void read_persistent_clock(struct timespec *ts)
{
unsigned long retval, flags;
@ -186,7 +186,8 @@ unsigned long read_persistent_clock(void)
retval = get_wallclock();
spin_unlock_irqrestore(&rtc_lock, flags);
return retval;
ts->tv_sec = retval;
ts->tv_nsec = 0;
}
int update_persistent_clock(struct timespec now)

5
arch/xtensa/kernel/time.c
View File

@ -59,9 +59,8 @@ static struct irqaction timer_irqaction = {
void __init time_init(void)
{
xtime.tv_nsec = 0;
xtime.tv_sec = read_persistent_clock();
/* FIXME: xtime&wall_to_monotonic are set in timekeeping_init. */
read_persistent_clock(&xtime);
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);

2
include/linux/time.h
View File

@ -101,7 +101,7 @@ extern struct timespec xtime;
extern struct timespec wall_to_monotonic;
extern seqlock_t xtime_lock;
extern unsigned long read_persistent_clock(void);
extern void read_persistent_clock(struct timespec *ts);
extern int update_persistent_clock(struct timespec now);
extern int no_sync_cmos_clock __read_mostly;
void timekeeping_init(void);

52
kernel/time/timekeeping.c
View File

@ -154,7 +154,7 @@ __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
*/
struct timespec xtime __attribute__ ((aligned (16)));
struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
static unsigned long total_sleep_time; /* seconds */
static struct timespec total_sleep_time;
/*
* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
@ -487,17 +487,18 @@ int timekeeping_valid_for_hres(void)
}
/**
* read_persistent_clock - Return time in seconds from the persistent clock.
* read_persistent_clock - Return time from the persistent clock.
*
* Weak dummy function for arches that do not yet support it.
* Returns seconds from epoch using the battery backed persistent clock.
* Returns zero if unsupported.
* Reads the time from the battery backed persistent clock.
* Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
*
* XXX - Do be sure to remove it once all arches implement it.
*/
unsigned long __attribute__((weak)) read_persistent_clock(void)
void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
{
return 0;
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
/*
@ -507,7 +508,9 @@ void __init timekeeping_init(void)
{
struct clocksource *clock;
unsigned long flags;
unsigned long sec = read_persistent_clock();
struct timespec now;
read_persistent_clock(&now);
write_seqlock_irqsave(&xtime_lock, flags);
@ -518,19 +521,20 @@ void __init timekeeping_init(void)
clock->enable(clock);
timekeeper_setup_internals(clock);
xtime.tv_sec = sec;
xtime.tv_nsec = 0;
xtime.tv_sec = now.tv_sec;
xtime.tv_nsec = now.tv_nsec;
raw_time.tv_sec = 0;
raw_time.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
update_xtime_cache(0);
total_sleep_time = 0;
total_sleep_time.tv_sec = 0;
total_sleep_time.tv_nsec = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
}
/* time in seconds when suspend began */
static unsigned long timekeeping_suspend_time;
static struct timespec timekeeping_suspend_time;
/**
* timekeeping_resume - Resumes the generic timekeeping subsystem.
@ -543,18 +547,19 @@ static unsigned long timekeeping_suspend_time;
static int timekeeping_resume(struct sys_device *dev)
{
unsigned long flags;
unsigned long now = read_persistent_clock();
struct timespec ts;
read_persistent_clock(&ts);
clocksource_resume();
write_seqlock_irqsave(&xtime_lock, flags);
if (now && (now > timekeeping_suspend_time)) {
unsigned long sleep_length = now - timekeeping_suspend_time;
xtime.tv_sec += sleep_length;
wall_to_monotonic.tv_sec -= sleep_length;
total_sleep_time += sleep_length;
if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
ts = timespec_sub(ts, timekeeping_suspend_time);
xtime = timespec_add_safe(xtime, ts);
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 */
@ -577,7 +582,7 @@ static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
{
unsigned long flags;
timekeeping_suspend_time = read_persistent_clock();
read_persistent_clock(&timekeeping_suspend_time);
write_seqlock_irqsave(&xtime_lock, flags);
timekeeping_forward_now();
@ -801,9 +806,10 @@ void update_wall_time(void)
*/
void getboottime(struct timespec *ts)
{
set_normalized_timespec(ts,
- (wall_to_monotonic.tv_sec + total_sleep_time),
- wall_to_monotonic.tv_nsec);
struct timespec boottime;
boottime = timespec_add_safe(wall_to_monotonic, total_sleep_time);
set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
}
/**
@ -812,7 +818,7 @@ void getboottime(struct timespec *ts)
*/
void monotonic_to_bootbased(struct timespec *ts)
{
ts->tv_sec += total_sleep_time;
*ts = timespec_add_safe(*ts, total_sleep_time);
}
unsigned long get_seconds(void)