linux-kernel - [PATCH] sched: skip autogroup when looking for all rt sched groups

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Date:	Wed, 22 Jun 2011 13:22:24 +0800
From:	Yong Zhang <yong.zhang0@...il.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>,
	Mike Galbraith <efault@....de>,
	Cheng Xu <chengxu@...ux.vnet.ibm.com>
Subject: [PATCH] sched: skip autogroup when looking for all rt sched groups

From: Yong Zhang <yong.zhang0@...il.com>
Subject: [PATCH] sched: skip autogroup when looking for all rt sched groups

Since [commit ec514c48: sched: Fix rt_rq runtime leakage bug],
'cat /proc/sched_debug' will print data of root_task_group.rt_rq
multi times, this is due to autogroup has no its own rt group,
instead rt group of autogroup is linked to root_task_group.

So skip it when we are looking for all rt sched groups, and it
will also save some noop operation against root_task_group when
__disable_runtime()/__enable_runtime().

Signed-off-by: Yong Zhang <yong.zhang0@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Mike Galbraith <efault@....de>
---

Since webmail may mangle the patch, attach it too.

 kernel/sched_autogroup.h |    1 +
 kernel/sched_rt.c        |   29 ++++++++++++++++++++++++-----
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/kernel/sched_autogroup.h b/kernel/sched_autogroup.h
index 0557705..c2f0e72 100644
--- a/kernel/sched_autogroup.h
+++ b/kernel/sched_autogroup.h
@@ -13,6 +13,7 @@ struct autogroup {
 	int			nice;
 };

+static inline bool task_group_is_autogroup(struct task_group *tg);
 static inline struct task_group *
 autogroup_task_group(struct task_struct *p, struct task_group *tg);

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 10d0182..8edf487 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -185,11 +185,30 @@ static inline u64 sched_rt_period(struct rt_rq *rt_rq)

 typedef struct task_group *rt_rq_iter_t;

-#define for_each_rt_rq(rt_rq, iter, rq) \
-	for (iter = list_entry_rcu(task_groups.next, typeof(*iter), list); \
-	     (&iter->list != &task_groups) && \
-	     (rt_rq = iter->rt_rq[cpu_of(rq)]); \
-	     iter = list_entry_rcu(iter->list.next, typeof(*iter), list))
+/* autogroup is not related to rt group, skip it */
+#define find_first_valid_task_group(iter)				\
+	({								\
+		list_for_each_entry_rcu(iter, &task_groups, list)	\
+			if (!task_group_is_autogroup(iter))		\
+				break;					\
+		iter;							\
+	})
+
+#define find_next_valid_task_group(iter)				\
+	({								\
+		do {							\
+			iter = list_entry_rcu(iter->list.next,		\
+					typeof(*iter),	list);		\
+		} while (&iter->list != &task_groups &&			\
+			task_group_is_autogroup(iter));			\
+		iter;							\
+	})
+
+#define for_each_rt_rq(rt_rq, iter, rq)					\
+	for (find_first_valid_task_group(iter);				\
+	     (&iter->list != &task_groups) &&				\
+	     (rt_rq = iter->rt_rq[cpu_of(rq)]);				\
+	     find_next_valid_task_group(iter))

 static inline void list_add_leaf_rt_rq(struct rt_rq *rt_rq)
 {
-- 
1.7.4.1

View attachment "0001-sched-skip-autogroup-when-looking-for-all-rt-sched-g.patch" of type "text/x-patch" (2747 bytes)