From 97813f2fe77804a4464564c75ba8d8826377feea Mon Sep 17 00:00:00 2001 From: Jon Hunter Date: Tue, 18 Aug 2009 12:45:11 -0500 Subject: 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 Cc: John Stultz LKML-Reference: <1250617512-23567-3-git-send-email-jon-hunter@ti.com> Signed-off-by: Thomas Gleixner --- kernel/hrtimer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/hrtimer.c') 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 -- cgit v1.2.3