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[PATCH] sched: TASK_NONINTERACTIVE

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This patch implements a task state bit (TASK_NONINTERACTIVE), which can be
used by blocking points to mark the task's wait as "non-interactive".  This
does not mean the task will be considered a CPU-hog - the wait will simply
not have an effect on the waiting task's priority - positive or negative
alike.  Right now only pipe_wait() will make use of it, because it's a
common source of not-so-interactive waits (kernel compilation jobs, etc.).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ingo Molnar 2005-09-10 00:26:12 -07:00 committed by Linus Torvalds
parent 95cdf3b799
commit d79fc0fc66
3 changed files with 16 additions and 2 deletions
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6
fs/pipe.c
View file

@ -39,7 +39,11 @@ void pipe_wait(struct inode * inode)
{
DEFINE_WAIT(wait);
prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE);
/*
* Pipes are system-local resources, so sleeping on them
* is considered a noninteractive wait:
*/
prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE|TASK_NONINTERACTIVE);
up(PIPE_SEM(*inode));
schedule();
finish_wait(PIPE_WAIT(*inode), &wait);

1
include/linux/sched.h
View file

@ -114,6 +114,7 @@ extern unsigned long nr_iowait(void);
#define TASK_TRACED 8
#define EXIT_ZOMBIE 16
#define EXIT_DEAD 32
#define TASK_NONINTERACTIVE 64
#define __set_task_state(tsk, state_value) \
do { (tsk)->state = (state_value); } while (0)

11
kernel/sched.c
View file

@ -1260,6 +1260,16 @@ static int try_to_wake_up(task_t *p, unsigned int state, int sync)
p->activated = -1;
}
/*
* Tasks that have marked their sleep as noninteractive get
* woken up without updating their sleep average. (i.e. their
* sleep is handled in a priority-neutral manner, no priority
* boost and no penalty.)
*/
if (old_state & TASK_NONINTERACTIVE)
__activate_task(p, rq);
else
activate_task(p, rq, cpu == this_cpu);
/*
* Sync wakeups (i.e. those types of wakeups where the waker
* has indicated that it will leave the CPU in short order)
@ -1268,7 +1278,6 @@ static int try_to_wake_up(task_t *p, unsigned int state, int sync)
* the waker guarantees that the freshly woken up task is going
* to be considered on this CPU.)
*/
activate_task(p, rq, cpu == this_cpu);
if (!sync || cpu != this_cpu) {
if (TASK_PREEMPTS_CURR(p, rq))
resched_task(rq->curr);