From 8f4d37ec073c17e2d4aa8851df5837d798606d6f Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 25 Jan 2008 21:08:29 +0100 Subject: sched: high-res preemption tick Use HR-timers (when available) to deliver an accurate preemption tick. The regular scheduler tick that runs at 1/HZ can be too coarse when nice level are used. The fairness system will still keep the cpu utilisation 'fair' by then delaying the task that got an excessive amount of CPU time but try to minimize this by delivering preemption points spot-on. The average frequency of this extra interrupt is sched_latency / nr_latency. Which need not be higher than 1/HZ, its just that the distribution within the sched_latency period is important. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- include/asm-x86/thread_info_32.h | 2 ++ include/asm-x86/thread_info_64.h | 5 +++++ include/linux/hrtimer.h | 9 +++++++++ include/linux/sched.h | 3 ++- 4 files changed, 18 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/asm-x86/thread_info_32.h b/include/asm-x86/thread_info_32.h index 22a8cbcd35e..ef58fd2a6eb 100644 --- a/include/asm-x86/thread_info_32.h +++ b/include/asm-x86/thread_info_32.h @@ -132,6 +132,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_SYSCALL_AUDIT 6 /* syscall auditing active */ #define TIF_SECCOMP 7 /* secure computing */ #define TIF_RESTORE_SIGMASK 8 /* restore signal mask in do_signal() */ +#define TIF_HRTICK_RESCHED 9 /* reprogram hrtick timer */ #define TIF_MEMDIE 16 #define TIF_DEBUG 17 /* uses debug registers */ #define TIF_IO_BITMAP 18 /* uses I/O bitmap */ @@ -147,6 +148,7 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_SYSCALL_AUDIT (1<base->get_time(); } +static inline int hrtimer_is_hres_active(struct hrtimer *timer) +{ + return timer->base->cpu_base->hres_active; +} + /* * The resolution of the clocks. The resolution value is returned in * the clock_getres() system call to give application programmers an @@ -248,6 +253,10 @@ static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer) return timer->base->softirq_time; } +static inline int hrtimer_is_hres_active(struct hrtimer *timer) +{ + return 0; +} #endif extern ktime_t ktime_get(void); diff --git a/include/linux/sched.h b/include/linux/sched.h index 7907845c234..43e0339d65f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -257,6 +257,7 @@ extern void trap_init(void); extern void account_process_tick(struct task_struct *task, int user); extern void update_process_times(int user); extern void scheduler_tick(void); +extern void hrtick_resched(void); extern void sched_show_task(struct task_struct *p); @@ -849,7 +850,7 @@ struct sched_class { #endif void (*set_curr_task) (struct rq *rq); - void (*task_tick) (struct rq *rq, struct task_struct *p); + void (*task_tick) (struct rq *rq, struct task_struct *p, int queued); void (*task_new) (struct rq *rq, struct task_struct *p); void (*set_cpus_allowed)(struct task_struct *p, cpumask_t *newmask); -- cgit v1.2.3