From bc947631d1d532c758f8fcbdeb1f7fc2f4c863f8 Mon Sep 17 00:00:00 2001 From: Peter Williams <pwil3058@bigpond.net.au> Date: Tue, 19 Dec 2006 12:48:50 +1000 Subject: [PATCH] sched: improve efficiency of sched_fork() Problem: sched_fork() has always called scheduler_tick() in some (unlikely) circumstances in order to update the current task in light of those circumstances. It has always been the case that the work done by scheduler_tick() was more than was required to handle the problem in hand but no harm was done except for the waste of a few CPU cycles. However, the splitting of scheduler_tick() into two procedures in 2.6.20-rc1 enables the wasted cycles to be saved as the new procedure task_running_tick() does all the work that is required to rectify the problem being handled. Solution: Replace the call to scheduler_tick() in sched_fork() with a call to task_running_tick(). Signed-off-by: Peter Williams <pwil3058@bigpond.com.au> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@osdl.org> --- kernel/sched.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched.c b/kernel/sched.c index 5cd833bc2173..b81ed8703f70 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1567,6 +1567,7 @@ int fastcall wake_up_state(struct task_struct *p, unsigned int state) return try_to_wake_up(p, state, 0); } +static void task_running_tick(struct rq *rq, struct task_struct *p); /* * Perform scheduler related setup for a newly forked process p. * p is forked by current. @@ -1627,7 +1628,7 @@ void fastcall sched_fork(struct task_struct *p, int clone_flags) * runqueue lock is not a problem. */ current->time_slice = 1; - scheduler_tick(); + task_running_tick(cpu_rq(cpu), current); } local_irq_enable(); put_cpu(); -- cgit v1.2.3-70-g09d2