summaryrefslogtreecommitdiff
path: root/include/linux/rtmutex.h
diff options
context:
space:
mode:
authorPeter Zijlstra <peterz@infradead.org>2013-11-07 17:43:43 +0400
committerIngo Molnar <mingo@kernel.org>2014-01-13 16:41:50 +0400
commitfb00aca474405f4fa8a8519c3179fed722eabd83 (patch)
tree8a779629a771dd3340d5a3ba0ba16b732b8de1c8 /include/linux/rtmutex.h
parentaf6ace764d03900524e9b1ac621a1c520ee49fc6 (diff)
downloadlinux-fb00aca474405f4fa8a8519c3179fed722eabd83.tar.xz
rtmutex: Turn the plist into an rb-tree
Turn the pi-chains from plist to rb-tree, in the rt_mutex code, and provide a proper comparison function for -deadline and -priority tasks. This is done mainly because: - classical prio field of the plist is just an int, which might not be enough for representing a deadline; - manipulating such a list would become O(nr_deadline_tasks), which might be to much, as the number of -deadline task increases. Therefore, an rb-tree is used, and tasks are queued in it according to the following logic: - among two -priority (i.e., SCHED_BATCH/OTHER/RR/FIFO) tasks, the one with the higher (lower, actually!) prio wins; - among a -priority and a -deadline task, the latter always wins; - among two -deadline tasks, the one with the earliest deadline wins. Queueing and dequeueing functions are changed accordingly, for both the list of a task's pi-waiters and the list of tasks blocked on a pi-lock. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Dario Faggioli <raistlin@linux.it> Signed-off-by: Juri Lelli <juri.lelli@gmail.com> Signed-off-again-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1383831828-15501-10-git-send-email-juri.lelli@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/rtmutex.h')
-rw-r--r--include/linux/rtmutex.h18
1 files changed, 6 insertions, 12 deletions
diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
index de17134244f3..3aed8d737e1a 100644
--- a/include/linux/rtmutex.h
+++ b/include/linux/rtmutex.h
@@ -13,7 +13,7 @@
#define __LINUX_RT_MUTEX_H
#include <linux/linkage.h>
-#include <linux/plist.h>
+#include <linux/rbtree.h>
#include <linux/spinlock_types.h>
extern int max_lock_depth; /* for sysctl */
@@ -22,12 +22,14 @@ extern int max_lock_depth; /* for sysctl */
* The rt_mutex structure
*
* @wait_lock: spinlock to protect the structure
- * @wait_list: pilist head to enqueue waiters in priority order
+ * @waiters: rbtree root to enqueue waiters in priority order
+ * @waiters_leftmost: top waiter
* @owner: the mutex owner
*/
struct rt_mutex {
raw_spinlock_t wait_lock;
- struct plist_head wait_list;
+ struct rb_root waiters;
+ struct rb_node *waiters_leftmost;
struct task_struct *owner;
#ifdef CONFIG_DEBUG_RT_MUTEXES
int save_state;
@@ -66,7 +68,7 @@ struct hrtimer_sleeper;
#define __RT_MUTEX_INITIALIZER(mutexname) \
{ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
- , .wait_list = PLIST_HEAD_INIT(mutexname.wait_list) \
+ , .waiters = RB_ROOT \
, .owner = NULL \
__DEBUG_RT_MUTEX_INITIALIZER(mutexname)}
@@ -98,12 +100,4 @@ extern int rt_mutex_trylock(struct rt_mutex *lock);
extern void rt_mutex_unlock(struct rt_mutex *lock);
-#ifdef CONFIG_RT_MUTEXES
-# define INIT_RT_MUTEXES(tsk) \
- .pi_waiters = PLIST_HEAD_INIT(tsk.pi_waiters), \
- INIT_RT_MUTEX_DEBUG(tsk)
-#else
-# define INIT_RT_MUTEXES(tsk)
-#endif
-
#endif