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authorJon Hunter <jon-hunter@ti.com>2009-08-18 12:45:11 -0500
committerThomas Gleixner <tglx@linutronix.de>2009-11-13 20:46:24 +0100
commit97813f2fe77804a4464564c75ba8d8826377feea (patch)
tree5dc7154c5687edaee5712408c8baf605463ff093 /kernel/hrtimer.c
parent27185016b806d5a1181ff501cae120582b2b27dd (diff)
downloadlinaro-lsk-97813f2fe77804a4464564c75ba8d8826377feea.tar.gz
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.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 6d7020490f9..c215b74cd95 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