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authorThomas Gleixner <tglx@linutronix.de>2011-05-20 23:14:04 +0200
committerThomas Gleixner <tglx@linutronix.de>2011-05-23 13:59:54 +0200
commit68fa61c026057a39d6ccb850aa8785043afbee02 (patch)
treeaa8a96849d4bd9b1e46c602d398cda0e72d4115c
parentab8177bc53e8ae3a3ba6d200ce2c2dae263f7ee5 (diff)
downloadlinux-68fa61c026057a39d6ccb850aa8785043afbee02.tar.bz2
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>
-rw-r--r--include/linux/hrtimer.h2
-rw-r--r--kernel/hrtimer.c12
2 files changed, 7 insertions, 7 deletions
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 771c95802edc..51932e5acf7c 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -153,8 +153,8 @@ struct hrtimer_clock_base {
};
enum hrtimer_base_type {
- HRTIMER_BASE_REALTIME,
HRTIMER_BASE_MONOTONIC,
+ HRTIMER_BASE_REALTIME,
HRTIMER_BASE_BOOTTIME,
HRTIMER_MAX_CLOCK_BASES,
};
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 1b08f6d67f12..c541ee527ecb 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -64,18 +64,18 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
.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,