From c19384b5b296905d4988c7c684ff540a0f9d65be Mon Sep 17 00:00:00 2001 From: Pierre Peiffer Date: Wed, 9 May 2007 02:35:02 -0700 Subject: Make futex_wait() use an hrtimer for timeout This patch modifies futex_wait() to use an hrtimer + schedule() in place of schedule_timeout(). schedule_timeout() is tick based, therefore the timeout granularity is the tick (1 ms, 4 ms or 10 ms depending on HZ). By using a high resolution timer for timeout wakeup, we can attain a much finer timeout granularity (in the microsecond range). This parallels what is already done for futex_lock_pi(). The timeout passed to the syscall is no longer converted to jiffies and is therefore passed to do_futex() and futex_wait() as an absolute ktime_t therefore keeping nanosecond resolution. Also this removes the need to pass the nanoseconds timeout part to futex_lock_pi() in val2. In futex_wait(), if there is no timeout then a regular schedule() is performed. Otherwise, an hrtimer is fired before schedule() is called. [akpm@linux-foundation.org: fix `make headers_check'] Signed-off-by: Sebastien Dugue Signed-off-by: Pierre Peiffer Cc: Ingo Molnar Cc: Ulrich Drepper Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/futex.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux/futex.h') diff --git a/include/linux/futex.h b/include/linux/futex.h index 820125c628c1..34e54f2b8997 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -3,6 +3,8 @@ #include +union ktime; + /* Second argument to futex syscall */ @@ -94,7 +96,7 @@ struct robust_list_head { #define ROBUST_LIST_LIMIT 2048 #ifdef __KERNEL__ -long do_futex(u32 __user *uaddr, int op, u32 val, unsigned long timeout, +long do_futex(u32 __user *uaddr, int op, u32 val, union ktime *timeout, u32 __user *uaddr2, u32 val2, u32 val3); extern int -- cgit v1.2.3-59-g8ed1b