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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 /include/linux | |
| 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 'include/linux')
| -rw-r--r-- | include/linux/clockchips.h | 8 |
1 files changed, 4 insertions, 4 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, |