[PATCH] sched: dont decrease idle sleep avg

e72ff0bb · Con Kolivas <[email protected]> · 2006-03-31 02:31:26 -08:00

We watch for tasks that sleep extended periods and don't allow one single
prolonged sleep period from elevating priority to maximum bonus to prevent cpu
bound tasks from getting high priority with single long sleeps.  There is a
bug in the current code that also penalises tasks that already have high
priority.  Correct that bug.

Signed-off-by: Con Kolivas <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: e72ff0bb2c163eb13014ba113701bd42dab382fe
Parents: e7c38cb4

Changes

1 files changed · +10 −5

File	Status	Add	Del	Content
kernel/sched.c	modified	+10	−5	View file

kernel/sched.c

View file

diff --git a/kernel/sched.c b/kernel/sched.c
index 589e55a..7b37193 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -700,14 +700,19 @@ static int recalc_task_prio(task_t *p, unsigned long long now)
 	if (likely(sleep_time > 0)) {
 		/*
 		 * User tasks that sleep a long time are categorised as
-		 * idle and will get just interactive status to stay active &
-		 * prevent them suddenly becoming cpu hogs and starving
-		 * other processes.
+		 * idle. They will only have their sleep_avg increased to a
+		 * level that makes them just interactive priority to stay
+		 * active yet prevent them suddenly becoming cpu hogs and
+		 * starving other processes.
 		 */
 		if (p->mm && p->sleep_type != SLEEP_NONINTERACTIVE &&
 			sleep_time > INTERACTIVE_SLEEP(p)) {
-				p->sleep_avg = JIFFIES_TO_NS(MAX_SLEEP_AVG -
-						DEF_TIMESLICE);
+				unsigned long ceiling;
+
+				ceiling = JIFFIES_TO_NS(MAX_SLEEP_AVG -
+					DEF_TIMESLICE);
+				if (p->sleep_avg < ceiling)
+					p->sleep_avg = ceiling;
 		} else {
 			/*
 			 * Tasks waking from uninterruptible sleep are