Messages in this thread Patch in this message | | | Date | Tue, 14 Feb 2006 11:11:00 +0100 (CET) | From | Roman Zippel <> | Subject | [PATCH 03/12] hrtimer: optimize hrtimer_run_queues |
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Every time hrtimer_run_queues() is called, get_time() is called twice, which can be quite expensive, just reading xtime is much cheaper and does the same job (at least for the current low resolution timer, for high resolution timer we can something different later). Cache the expiry time in last_expired, so run_hrtimer_queue() doesn't has to calculate it (clock sources usually know when their expired).
Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Acked-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/hrtimer.h | 1 + kernel/hrtimer.c | 17 +++++++++++++---- 2 files changed, 14 insertions(+), 4 deletions(-)
Index: linux-2.6-git/include/linux/hrtimer.h =================================================================== --- linux-2.6-git.orig/include/linux/hrtimer.h 2006-02-13 22:29:45.000000000 +0100 +++ linux-2.6-git/include/linux/hrtimer.h 2006-02-13 22:29:56.000000000 +0100 @@ -89,6 +89,7 @@ struct hrtimer_base { ktime_t resolution; ktime_t (*get_time)(void); struct hrtimer *curr_timer; + ktime_t last_expired; }; /* Index: linux-2.6-git/kernel/hrtimer.c =================================================================== --- linux-2.6-git.orig/kernel/hrtimer.c 2006-02-13 22:29:51.000000000 +0100 +++ linux-2.6-git/kernel/hrtimer.c 2006-02-13 22:29:56.000000000 +0100 @@ -541,7 +541,7 @@ int hrtimer_get_res(const clockid_t whic */ static inline void run_hrtimer_queue(struct hrtimer_base *base) { - ktime_t now = base->get_time(); + ktime_t now = base->last_expired; struct rb_node *node; spin_lock_irq(&base->lock); @@ -594,10 +594,19 @@ static inline void run_hrtimer_queue(str void hrtimer_run_queues(void) { struct hrtimer_base *base = __get_cpu_var(hrtimer_bases); - int i; + ktime_t now, mono; + int seq; - for (i = 0; i < MAX_HRTIMER_BASES; i++) - run_hrtimer_queue(&base[i]); + do { + seq = read_seqbegin(&xtime_lock); + now = timespec_to_ktime(xtime); + mono = timespec_to_ktime(wall_to_monotonic); + } while (read_seqretry(&xtime_lock, seq)); + + base[CLOCK_REALTIME].last_expired = now; + run_hrtimer_queue(&base[CLOCK_REALTIME]); + base[CLOCK_MONOTONIC].last_expired = ktime_add(now, mono); + run_hrtimer_queue(&base[CLOCK_MONOTONIC]); } /* - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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