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author | 2009-08-18 12:45:11 -0500 | |
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committer | 2009-11-13 20:46:24 +0100 | |
commit | 97813f2fe77804a4464564c75ba8d8826377feea (patch) | |
tree | 5dc7154c5687edaee5712408c8baf605463ff093 | |
parent | nohz: Track last do_timer() cpu (diff) | |
download | linux-97813f2fe77804a4464564c75ba8d8826377feea.tar.gz linux-97813f2fe77804a4464564c75ba8d8826377feea.tar.bz2 linux-97813f2fe77804a4464564c75ba8d8826377feea.zip |
nohz: Allow 32-bit machines to sleep for more than 2.15 seconds
In the dynamic tick code, "max_delta_ns" (member of the
"clock_event_device" structure) represents the maximum sleep time
that can occur between timer events in nanoseconds.
The variable, "max_delta_ns", is defined as an unsigned long
which is a 32-bit integer for 32-bit machines and a 64-bit
integer for 64-bit machines (if -m64 option is used for gcc).
The value of max_delta_ns is set by calling the function
"clockevent_delta2ns()" which returns a maximum value of LONG_MAX.
For a 32-bit machine LONG_MAX is equal to 0x7fffffff and in
nanoseconds this equates to ~2.15 seconds. Hence, the maximum
sleep time for a 32-bit machine is ~2.15 seconds, where as for
a 64-bit machine it will be many years.
This patch changes the type of max_delta_ns to be "u64" instead of
"unsigned long" so that this variable is a 64-bit type for both 32-bit
and 64-bit machines. It also changes the maximum value returned by
clockevent_delta2ns() to KTIME_MAX. Hence this allows a 32-bit
machine to sleep for longer than ~2.15 seconds. Please note that this
patch also changes "min_delta_ns" to be "u64" too and although this is
unnecessary, it makes the patch simpler as it avoids to fixup all
callers of clockevent_delta2ns().
[ tglx: changed "unsigned long long" to u64 as we use this data type
through out the time code ]
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Cc: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <1250617512-23567-3-git-send-email-jon-hunter@ti.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r-- | include/linux/clockchips.h | 8 | ||||
-rw-r--r-- | kernel/hrtimer.c | 3 | ||||
-rw-r--r-- | kernel/time/clockevents.c | 11 | ||||
-rw-r--r-- | kernel/time/tick-oneshot.c | 4 | ||||
-rw-r--r-- | kernel/time/timer_list.c | 6 |
5 files changed, 17 insertions, 15 deletions
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h index 4d438b0bc10a..0cf725bdd2a1 100644 --- a/include/linux/clockchips.h +++ b/include/linux/clockchips.h @@ -77,8 +77,8 @@ enum clock_event_nofitiers { struct clock_event_device { const char *name; unsigned int features; - unsigned long max_delta_ns; - unsigned long min_delta_ns; + u64 max_delta_ns; + u64 min_delta_ns; u32 mult; u32 shift; int rating; @@ -116,8 +116,8 @@ static inline unsigned long div_sc(unsigned long ticks, unsigned long nsec, } /* Clock event layer functions */ -extern unsigned long clockevent_delta2ns(unsigned long latch, - struct clock_event_device *evt); +extern u64 clockevent_delta2ns(unsigned long latch, + struct clock_event_device *evt); extern void clockevents_register_device(struct clock_event_device *dev); extern void clockevents_exchange_device(struct clock_event_device *old, diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 6d7020490f94..c215b74cd953 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1240,7 +1240,8 @@ hrtimer_interrupt_hanging(struct clock_event_device *dev, force_clock_reprogram = 1; dev->min_delta_ns = (unsigned long)try_time.tv64 * 3; printk(KERN_WARNING "hrtimer: interrupt too slow, " - "forcing clock min delta to %lu ns\n", dev->min_delta_ns); + "forcing clock min delta to %llu ns\n", + (unsigned long long) dev->min_delta_ns); } /* * High resolution timer interrupt diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 620b58abdc32..05e8aeedcdf3 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -37,10 +37,9 @@ static DEFINE_SPINLOCK(clockevents_lock); * * Math helper, returns latch value converted to nanoseconds (bound checked) */ -unsigned long clockevent_delta2ns(unsigned long latch, - struct clock_event_device *evt) +u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt) { - u64 clc = ((u64) latch << evt->shift); + u64 clc = (u64) latch << evt->shift; if (unlikely(!evt->mult)) { evt->mult = 1; @@ -50,10 +49,10 @@ unsigned long clockevent_delta2ns(unsigned long latch, do_div(clc, evt->mult); if (clc < 1000) clc = 1000; - if (clc > LONG_MAX) - clc = LONG_MAX; + if (clc > KTIME_MAX) + clc = KTIME_MAX; - return (unsigned long) clc; + return clc; } EXPORT_SYMBOL_GPL(clockevent_delta2ns); diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c index a96c0e2b89cf..0a8a213016f0 100644 --- a/kernel/time/tick-oneshot.c +++ b/kernel/time/tick-oneshot.c @@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires, dev->min_delta_ns += dev->min_delta_ns >> 1; printk(KERN_WARNING - "CE: %s increasing min_delta_ns to %lu nsec\n", + "CE: %s increasing min_delta_ns to %llu nsec\n", dev->name ? dev->name : "?", - dev->min_delta_ns << 1); + (unsigned long long) dev->min_delta_ns << 1); i = 0; } diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c index fa00da108a14..665c76edbf17 100644 --- a/kernel/time/timer_list.c +++ b/kernel/time/timer_list.c @@ -204,8 +204,10 @@ print_tickdevice(struct seq_file *m, struct tick_device *td, int cpu) return; } SEQ_printf(m, "%s\n", dev->name); - SEQ_printf(m, " max_delta_ns: %lu\n", dev->max_delta_ns); - SEQ_printf(m, " min_delta_ns: %lu\n", dev->min_delta_ns); + SEQ_printf(m, " max_delta_ns: %llu\n", + (unsigned long long) dev->max_delta_ns); + SEQ_printf(m, " min_delta_ns: %llu\n", + (unsigned long long) dev->min_delta_ns); SEQ_printf(m, " mult: %u\n", dev->mult); SEQ_printf(m, " shift: %u\n", dev->shift); SEQ_printf(m, " mode: %d\n", dev->mode); |