hrtimers: Reorder clock bases
The ordering of the clock bases is historical due to the
CLOCK_REALTIME and CLOCK_MONOTONIC constants. Now the hrtimer bases
have their own enumeration due to the gap between CLOCK_MONOTONIC and
CLOCK_BOOTTIME. So we can be more clever as most timers end up on the
CLOCK_MONOTONIC base due to the virtue of POSIX declaring that
relative CLOCK_REALTIME timers are not affected by time changes. In
desktop environments this is slowly changing as applications switch to
absolute timers, but I've observed empty CLOCK_REALTIME bases often
enough. There is no performance penalty or overhead when
CLOCK_REALTIME timers are active, but in case they are not we don't
skip over a full cache line.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 1b08f6d..c541ee5 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -64,18 +64,18 @@
.clock_base =
{
{
- .index = HRTIMER_BASE_REALTIME,
- .clockid = CLOCK_REALTIME,
- .get_time = &ktime_get_real,
- .resolution = KTIME_LOW_RES,
- },
- {
.index = HRTIMER_BASE_MONOTONIC,
.clockid = CLOCK_MONOTONIC,
.get_time = &ktime_get,
.resolution = KTIME_LOW_RES,
},
{
+ .index = HRTIMER_BASE_REALTIME,
+ .clockid = CLOCK_REALTIME,
+ .get_time = &ktime_get_real,
+ .resolution = KTIME_LOW_RES,
+ },
+ {
.index = HRTIMER_BASE_BOOTTIME,
.clockid = CLOCK_BOOTTIME,
.get_time = &ktime_get_boottime,