lkml.org 
[lkml]   [2009]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:timers/core] timekeeping: Increase granularity of read_persistent_clock()
Commit-ID:  d4f587c67fc39e0030ddd718675e252e208da4d7
Gitweb: http://git.kernel.org/tip/d4f587c67fc39e0030ddd718675e252e208da4d7
Author: Martin Schwidefsky <schwidefsky@de.ibm.com>
AuthorDate: Fri, 14 Aug 2009 15:47:31 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 15 Aug 2009 10:55:46 +0200

timekeeping: Increase granularity of read_persistent_clock()

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>


---
arch/m68knommu/kernel/time.c | 5 ++-
arch/mips/dec/time.c | 5 ++-
arch/mips/lasat/ds1603.c | 5 ++-
arch/mips/lasat/sysctl.c | 8 ++++-
arch/mips/lemote/lm2e/setup.c | 5 ++-
arch/mips/mti-malta/malta-time.c | 5 ++-
arch/mips/pmc-sierra/yosemite/setup.c | 5 ++-
arch/mips/sibyte/swarm/setup.c | 15 +++++++--
arch/mips/sni/time.c | 5 ++-
arch/powerpc/kernel/time.c | 7 ++--
arch/s390/kernel/time.c | 22 ++-----------
arch/sh/kernel/time.c | 6 +--
arch/x86/kernel/rtc.c | 5 ++-
arch/xtensa/kernel/time.c | 5 +--
include/linux/time.h | 2 +-
kernel/time/timekeeping.c | 52 ++++++++++++++++++--------------
16 files changed, 83 insertions(+), 74 deletions(-)

diff --git a/arch/m68knommu/kernel/time.c b/arch/m68knommu/kernel/time.c
index d182b2f..6843224 100644
--- a/arch/m68knommu/kernel/time.c
+++ b/arch/m68knommu/kernel/time.c
@@ -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)
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c
index 463136e..02f505f 100644
--- a/arch/mips/dec/time.c
+++ b/arch/mips/dec/time.c
@@ -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;
}

/*
diff --git a/arch/mips/lasat/ds1603.c b/arch/mips/lasat/ds1603.c
index 52cb143..c6fd96f 100644
--- a/arch/mips/lasat/ds1603.c
+++ b/arch/mips/lasat/ds1603.c
@@ -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)
diff --git a/arch/mips/lasat/sysctl.c b/arch/mips/lasat/sysctl.c
index 8f88886..3f04d4c 100644
--- a/arch/mips/lasat/sysctl.c
+++ b/arch/mips/lasat/sysctl.c
@@ -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);
diff --git a/arch/mips/lemote/lm2e/setup.c b/arch/mips/lemote/lm2e/setup.c
index ebd6cea..24b355d 100644
--- a/arch/mips/lemote/lm2e/setup.c
+++ b/arch/mips/lemote/lm2e/setup.c
@@ -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);
diff --git a/arch/mips/mti-malta/malta-time.c b/arch/mips/mti-malta/malta-time.c
index 0b97d47..3c6f190 100644
--- a/arch/mips/mti-malta/malta-time.c
+++ b/arch/mips/mti-malta/malta-time.c
@@ -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)
diff --git a/arch/mips/pmc-sierra/yosemite/setup.c b/arch/mips/pmc-sierra/yosemite/setup.c
index 2d3c0dc..3498ac9 100644
--- a/arch/mips/pmc-sierra/yosemite/setup.c
+++ b/arch/mips/pmc-sierra/yosemite/setup.c
@@ -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)
diff --git a/arch/mips/sibyte/swarm/setup.c b/arch/mips/sibyte/swarm/setup.c
index 672e45d..623ffc9 100644
--- a/arch/mips/sibyte/swarm/setup.c
+++ b/arch/mips/sibyte/swarm/setup.c
@@ -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)
diff --git a/arch/mips/sni/time.c b/arch/mips/sni/time.c
index 0d9ec1a..62df6a5 100644
--- a/arch/mips/sni/time.c
+++ b/arch/mips/sni/time.c
@@ -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;
}
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index eae4511..ad63f30 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -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 */
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index e76c2e7..a94ec48 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -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);
diff --git a/arch/sh/kernel/time.c b/arch/sh/kernel/time.c
index 9b352a1..3f4706a 100644
--- a/arch/sh/kernel/time.c
+++ b/arch/sh/kernel/time.c
@@ -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)
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 5d465b2..bf67dcb 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -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)
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index 8848120..19085ff 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -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);

diff --git a/include/linux/time.h b/include/linux/time.h
index e7c8445..53a3216 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -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);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 41579e7..f1a21ce 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -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)

\
 
 \ /
  Last update: 2009-08-15 11:27    [W:0.189 / U:5.028 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site