From 68fa61c026057a39d6ccb850aa8785043afbee02 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 20 May 2011 23:14:04 +0200 Subject: [PATCH] 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 Reviewed-by: Peter Zijlstra --- 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 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 @@ -63,18 +63,18 @@ 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, -- 2.20.1