Commit-ID: 5218424f2634939bc0deeaea93340010913aca7c
Gitweb: http://git.kernel.org/tip/5218424f2634939bc0deeaea93340010913aca7c
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Fri, 20 May 2011 23:14:04 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 23 May 2011 12:24:18 +0200
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@xxxxxxxxxxxxx>
Reviewed-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
include/linux/hrtimer.h | 2 +-
kernel/hrtimer.c | 12 ++++++------
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 1a4a60b..c41787c 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 1b08f6d..c541ee5 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,
--
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