From f1b82746c1e93daf24e1ab9bfbd39bcdb2e7018b Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Fri, 14 Aug 2009 15:47:21 +0200 Subject: clocksource: Cleanup clocksource selection If a non high-resolution clocksource is first set as override clock and then registered it becomes active even if the system is in one-shot mode. Move the override check from sysfs_override_clocksource to the clocksource selection. That fixes the bug and simplifies the code. The check in clocksource_register for double registration of the same clocksource is removed without replacement. To find the initial clocksource a new weak function in jiffies.c is defined that returns the jiffies clocksource. The architecture code can then override the weak function with a more suitable clocksource, e.g. the TOD clock on s390. [ tglx: Folded in a fix from John Stultz ] Signed-off-by: Martin Schwidefsky Acked-by: John Stultz Cc: Daniel Walker LKML-Reference: <20090814134808.388024160@de.ibm.com> Signed-off-by: Thomas Gleixner --- arch/s390/kernel/time.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/s390/kernel/time.c') diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index d4c8e9c47c8..afefe514df0 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -205,6 +205,10 @@ static struct clocksource clocksource_tod = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; +struct clocksource * __init clocksource_default_clock(void) +{ + return &clocksource_tod; +} void update_vsyscall(struct timespec *wall_time, struct clocksource *clock) { -- cgit v1.2.3 From 155ec60226ae0ae2aadaa57c951a58a359331030 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Fri, 14 Aug 2009 15:47:26 +0200 Subject: timekeeping: Introduce struct timekeeper Add struct timekeeper to keep the internal values timekeeping.c needs in regard to the currently selected clock source. This moves the timekeeping intervals, xtime_nsec and the ntp error value from struct clocksource to struct timekeeper. The raw_time is removed from the clocksource as well. It gets treated like xtime as a global variable. Eventually xtime raw_time should be moved to struct timekeeper. [ tglx: minor cleanup ] Signed-off-by: Martin Schwidefsky Cc: Ingo Molnar Acked-by: John Stultz Cc: Daniel Walker LKML-Reference: <20090814134809.613209842@de.ibm.com> Signed-off-by: Thomas Gleixner --- arch/s390/kernel/time.c | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/s390/kernel/time.c') diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index afefe514df0..e76c2e7a8b9 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -280,7 +280,6 @@ void __init time_init(void) now = get_clock(); tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime); clocksource_tod.cycle_last = now; - clocksource_tod.raw_time = xtime; 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); -- cgit v1.2.3 From d4f587c67fc39e0030ddd718675e252e208da4d7 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Fri, 14 Aug 2009 15:47:31 +0200 Subject: 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 Cc: Ingo Molnar Acked-by: John Stultz Cc: Daniel Walker LKML-Reference: <20090814134811.013873340@de.ibm.com> Signed-off-by: Thomas Gleixner --- arch/s390/kernel/time.c | 22 ++++------------------ 1 file changed, 4 insertions(+), 18 deletions(-) (limited to 'arch/s390/kernel/time.c') diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index e76c2e7a8b9..a94ec48587b 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); -- cgit v1.2.3 From 23970e389e9cee43c4b41023935e1417271708b2 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Fri, 14 Aug 2009 15:47:32 +0200 Subject: timekeeping: Introduce read_boot_clock Add the new function read_boot_clock to get the exact time the system has been started. For architectures without support for exact boot time a new weak function is added that returns 0. Use the exact boot time to initialize wall_to_monotonic, or xtime if the read_boot_clock returned 0. Signed-off-by: Martin Schwidefsky Cc: Ingo Molnar Acked-by: John Stultz Cc: Daniel Walker LKML-Reference: <20090814134811.296703241@de.ibm.com> Signed-off-by: Thomas Gleixner --- arch/s390/kernel/time.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) (limited to 'arch/s390/kernel/time.c') diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index a94ec48587b..6bff1a1d906 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -187,6 +187,11 @@ void read_persistent_clock(struct timespec *ts) tod_to_timeval(get_clock() - TOD_UNIX_EPOCH, ts); } +void read_boot_clock(struct timespec *ts) +{ + tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, ts); +} + static cycle_t read_tod_clock(struct clocksource *cs) { return get_clock(); @@ -243,9 +248,6 @@ void update_vsyscall_tz(void) */ void __init time_init(void) { - struct timespec ts; - unsigned long flags; - /* Reset time synchronization interfaces. */ etr_reset(); stp_reset(); @@ -261,15 +263,6 @@ void __init time_init(void) if (clocksource_register(&clocksource_tod) != 0) panic("Could not register TOD clock source"); - /* - * 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); - 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); - /* Enable TOD clock interrupts on the boot cpu. */ init_cpu_timer(); -- cgit v1.2.3