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| author | Jon Hunter <jon-hunter@ti.com> | 2009-08-18 12:45:11 -0500 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2009-11-13 20:46:24 +0100 |
| commit | 97813f2fe77804a4464564c75ba8d8826377feea (patch) | |
| tree | 5dc7154c5687edaee5712408c8baf605463ff093 /kernel/hrtimer.c | |
| parent | 27185016b806d5a1181ff501cae120582b2b27dd (diff) | |
| download | linux-stable-97813f2fe77804a4464564c75ba8d8826377feea.tar.gz linux-stable-97813f2fe77804a4464564c75ba8d8826377feea.tar.bz2 linux-stable-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>
Diffstat (limited to 'kernel/hrtimer.c')
| -rw-r--r-- | kernel/hrtimer.c | 3 |
1 files changed, 2 insertions, 1 deletions
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 |