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locking/rwlocks: Add contention detection for rwlocks

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rwlocks do not currently have any facility to detect contention
like spinlocks do. In order to allow users of rwlocks to better manage
latency, add contention detection for queued rwlocks.

CC: Ingo Molnar <[email protected]>
CC: Will Deacon <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Acked-by: Davidlohr Bueso <[email protected]>
Acked-by: Waiman Long <[email protected]>
Acked-by: Paolo Bonzini <[email protected]>
Signed-off-by: Ben Gardon <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
This commit is contained in:
Ben Gardon authored and Paolo Bonzini committed 2021-02-04 05:27:42 -05:00
1 parent 7cca2d0b7e
commit 26128cb6c7
2 files changed
+25 -6
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include/asm-generic/qrwlock.h
+18 -6
View File
@@ -14,6 +14,7 @@
#include <asm/processor.h>
#include <asm-generic/qrwlock_types.h>
#include <asm-generic/qspinlock.h>
/*
* Writer states & reader shift and bias.
@@ -116,15 +117,26 @@ static inline void queued_write_unlock(struct qrwlock *lock)
smp_store_release(&lock->wlocked, 0);
}
/**
* queued_rwlock_is_contended - check if the lock is contended
* @lock : Pointer to queue rwlock structure
* Return: 1 if lock contended, 0 otherwise
*/
static inline int queued_rwlock_is_contended(struct qrwlock *lock)
{
return arch_spin_is_locked(&lock->wait_lock);
}
/*
* Remapping rwlock architecture specific functions to the corresponding
* queue rwlock functions.
*/
#define arch_read_lock(l) queued_read_lock(l)
#define arch_write_lock(l) queued_write_lock(l)
#define arch_read_trylock(l) queued_read_trylock(l)
#define arch_write_trylock(l) queued_write_trylock(l)
#define arch_read_unlock(l) queued_read_unlock(l)
#define arch_write_unlock(l) queued_write_unlock(l)
#define arch_read_lock(l) queued_read_lock(l)
#define arch_write_lock(l) queued_write_lock(l)
#define arch_read_trylock(l) queued_read_trylock(l)
#define arch_write_trylock(l) queued_write_trylock(l)
#define arch_read_unlock(l) queued_read_unlock(l)
#define arch_write_unlock(l) queued_write_unlock(l)
#define arch_rwlock_is_contended(l) queued_rwlock_is_contended(l)
#endif /* __ASM_GENERIC_QRWLOCK_H */
include/linux/rwlock.h
+7
View File
@@ -128,4 +128,11 @@ do { \
1 : ({ local_irq_restore(flags); 0; }); \
})
#ifdef arch_rwlock_is_contended
#define rwlock_is_contended(lock) \
arch_rwlock_is_contended(&(lock)->raw_lock)
#else
#define rwlock_is_contended(lock) ((void)(lock), 0)
#endif /* arch_rwlock_is_contended */
#endif /* __LINUX_RWLOCK_H */