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Remove adaptive mutex implementation

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Since the Linux 2.6.29 kernel all mutexes have been adaptive mutexs.
There is no longer any point in keeping this code so it is being
removed to simplify the code.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Brian Behlendorf
2014-09-29 16:48:35 -04:00
parent 56cfabd3e8
commit a80d69caf0
4 changed files with 9 additions and 124 deletions
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include/sys/mutex.h
+6 -40
View File
@@ -35,7 +35,8 @@ typedef enum {
MUTEX_ADAPTIVE = 2
} kmutex_type_t;
#if defined(HAVE_MUTEX_OWNER) && defined(CONFIG_SMP) && !defined(CONFIG_DEBUG_MUTEXES)
#if defined(HAVE_MUTEX_OWNER) && defined(CONFIG_SMP) && \
!defined(CONFIG_DEBUG_MUTEXES)
/*
* We define a 1-field struct rather than a straight typedef to enforce type
@@ -82,7 +83,7 @@ mutex_owner(kmutex_t *mp)
({ \
ASSERT3P(mutex_owner(mp), !=, current); \
mutex_lock(&(mp)->m); \
})
})
#define mutex_exit(mp) mutex_unlock(&(mp)->m)
#else /* HAVE_MUTEX_OWNER */
@@ -92,13 +93,6 @@ typedef struct {
kthread_t *m_owner;
} kmutex_t;
#ifdef HAVE_TASK_CURR
extern int spl_mutex_spin_max(void);
#else /* HAVE_TASK_CURR */
# define task_curr(owner) 0
# define spl_mutex_spin_max() 0
#endif /* HAVE_TASK_CURR */
#define MUTEX(mp) (&((mp)->m_mutex))
static inline void
@@ -150,39 +144,11 @@ spl_mutex_clear_owner(kmutex_t *mp)
_rc_; \
})
/*
* Adaptive mutexs assume that the lock may be held by a task running
* on a different cpu. The expectation is that the task will drop the
* lock before leaving the head of the run queue. So the ideal thing
* to do is spin until we acquire the lock and avoid a context switch.
* However it is also possible the task holding the lock yields the
* processor with out dropping lock. In this case, we know it's going
* to be a while so we stop spinning and go to sleep waiting for the
* lock to be available. This should strike the optimum balance
* between spinning and sleeping waiting for a lock.
*/
#define mutex_enter(mp) \
({ \
kthread_t *_owner_; \
int _rc_, _count_; \
\
_rc_ = 0; \
_count_ = 0; \
_owner_ = mutex_owner(mp); \
ASSERT3P(_owner_, !=, current); \
\
while (_owner_ && task_curr(_owner_) && \
_count_ <= spl_mutex_spin_max()) { \
if ((_rc_ = mutex_trylock(MUTEX(mp)))) \
break; \
\
_count_++; \
} \
\
if (!_rc_) \
mutex_lock(MUTEX(mp)); \
\
spl_mutex_set_owner(mp); \
ASSERT3P(mutex_owner(mp), !=, current); \
mutex_lock(MUTEX(mp)); \
spl_mutex_set_owner(mp); \
})
#define mutex_exit(mp) \