linux-kernel - [PATCH 1/2] sched: Make set_*_buddy work on non-task entity -v2

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Date:	Wed, 13 Apr 2011 18:21:09 -0700
From:	Venkatesh Pallipadi <venki@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Paul Turner <pjt@...gle.com>, Mike Galbraith <efault@....de>,
	Rik van Riel <riel@...hat.com>,
	Venkatesh Pallipadi <venki@...gle.com>
Subject: [PATCH 1/2] sched: Make set_*_buddy work on non-task entity -v2

Make set_*_buddy work on non-task sched_entity, to facilitate the
use of next_buddy to cache a group entity in cases where one of the tasks
within that entity sleeps or gets preempted.

set_skip_buddy was wrongly comparing the policy of task that is yielding
to be not equal to SCHED_IDLE. Yielding should happen even when task yielding
is SCHED_IDLE. This change removes the policy check on the yielding task.

Signed-off-by: Venkatesh Pallipadi <venki@...gle.com>
---
 kernel/sched_fair.c |   24 ++++++++++++------------
 1 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 80ecd09..d3513b7 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1826,26 +1826,26 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
 
 static void set_last_buddy(struct sched_entity *se)
 {
-	if (likely(task_of(se)->policy != SCHED_IDLE)) {
-		for_each_sched_entity(se)
-			cfs_rq_of(se)->last = se;
-	}
+	if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
+		return;
+
+	for_each_sched_entity(se)
+		cfs_rq_of(se)->last = se;
 }
 
 static void set_next_buddy(struct sched_entity *se)
 {
-	if (likely(task_of(se)->policy != SCHED_IDLE)) {
-		for_each_sched_entity(se)
-			cfs_rq_of(se)->next = se;
-	}
+	if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
+		return;
+
+	for_each_sched_entity(se)
+		cfs_rq_of(se)->next = se;
 }
 
 static void set_skip_buddy(struct sched_entity *se)
 {
-	if (likely(task_of(se)->policy != SCHED_IDLE)) {
-		for_each_sched_entity(se)
-			cfs_rq_of(se)->skip = se;
-	}
+	for_each_sched_entity(se)
+		cfs_rq_of(se)->skip = se;
 }
 
 /*
-- 
1.7.3.1

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