[PATCH] sched: TASK_NONINTERACTIVE

d79fc0fc · Ingo Molnar <[email protected]> · 2005-09-10 00:26:12 -07:00

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 <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: d79fc0fc6645b0cf5cd980da76942ca6d6300fa4
Parents: 95cdf3b7

Changes

3 files changed · +16 −2

File	Status	Add	Del	Content
fs/pipe.c	modified	+5	−1	View file
include/linux/sched.h	modified	+1	−0	View file
kernel/sched.c	modified	+10	−1	View file

fs/pipe.c

View file

diff --git a/fs/pipe.c b/fs/pipe.c
index 2c7a23d..66aa0b9 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -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);

include/linux/sched.h

View file

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8a1fcfe..ac70f84 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -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)

kernel/sched.c

View file

diff --git a/kernel/sched.c b/kernel/sched.c
index 24eed37..6da13bb 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1261,6 +1261,16 @@ out_activate:
 	}
 
 	/*
+	 * 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)
 	 * don't trigger a preemption, if the woken up task will run on
@@ -1268,7 +1278,6 @@ out_activate:
 	 * 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);