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NAMECK_ELIDE_PROTOTYPE ,
CK_ELIDE_LOCK_ADAPTIVE ,
CK_ELIDE_UNLOCK_ADAPTIVE ,
CK_ELIDE_LOCK ,
CK_ELIDE_UNLOCK ,
CK_ELIDE_TRYLOCK_PROTOTYPE ,
CK_ELIDE_TRYLOCK —
lock elision wrappers
LIBRARYConcurrency Kit (libck, -lck)SYNOPSIS#include <ck_elide.h>
struct ck_elide_config { unsigned short skip_busy; short retry_busy; unsigned short skip_other; short retry_other; unsigned short skip_conflict; short retry_conflict; };
DESCRIPTIONThese macros implement lock elision wrappers for a user-specified single-argument lock interface. The wrappers will attempt to elide lock acquisition, allowing concurrent execution of critical sections that do not issue conflicting memory operations. If any threads have successfully elided a lock acquisition, conflicting memory operations will roll-back any side-effects of the critical section and force every thread to retry the lock acquisition regularly.
Both ck_spinlock.h and ck_rwlock.h define ck_elide wrappers under the ck_spinlock and ck_rwlock namespace, respectively. EXAMPLESThis example utilizes built-in lock elision facilities in ck_rwlock and ck_spinlock.#include <ck_rwlock.h> #include <ck_spinlock.h> static ck_rwlock_t rw = CK_RWLOCK_INITIALIZER; static struct ck_elide_config rw_config = CK_ELIDE_CONFIG_DEFAULT_INITIALIZER; static __thread ck_elide_stat_t rw_stat = CK_ELIDE_STAT_INITIALIZER; static ck_spinlock_t spinlock = CK_SPINLOCK_INITIALIZER; static struct ck_elide_config spinlock_config = CK_ELIDE_CONFIG_DEFAULT_INITIALIZER; static __thread ck_elide_stat_t spinlock_stat = CK_ELIDE_STAT_INITIALIZER; void function(void) { /* Lock-unlock write-side lock in weak best-effort manner. */ CK_ELIDE_LOCK(ck_rwlock_write, &rw); CK_ELIDE_UNLOCK(ck_rwlock_write, &rw); /* Attempt to acquire the write-side lock. */ if (CK_ELIDE_TRYLOCK(ck_rwlock_write, &rw) == true) CK_ELIDE_UNLOCK(ck_rwlock_write, &rw); /* Lock-unlock read-side lock in weak best-effort manner. */ CK_ELIDE_LOCK(ck_rwlock_read, &rw); CK_ELIDE_UNLOCK(ck_rwlock_read, &rw); /* Attempt to acquire the read-side lock. */ if (CK_ELIDE_TRYLOCK(ck_rwlock_read, &rw) == true) CK_ELIDE_UNLOCK(ck_rwlock_read, &rw); /* Lock-unlock write-side lock in an adaptive manner. */ CK_ELIDE_LOCK_ADAPTIVE(ck_rwlock_write, &rw_stat, &rw_config, &rw); CK_ELIDE_UNLOCK_ADAPTIVE(ck_rwlock_write, &rw_stat, &rw_config, &rw); /* Lock-unlock read-side lock in an adaptive manner. */ CK_ELIDE_LOCK_ADAPTIVE(ck_rwlock_read, &rw_stat, &rw_config, &rw); CK_ELIDE_UNLOCK_ADAPTIVE(ck_rwlock_read, &rw_stat, &rw_config, &rw); /* Lock-unlock spinlock in weak best-effort manner. */ CK_ELIDE_LOCK(ck_spinlock, &spinlock); CK_ELIDE_UNLOCK(ck_spinlock, &spinlock); /* Attempt to acquire the lock. */ if (CK_ELIDE_TRYLOCK(ck_spinlock, &lock) == true) CK_ELIDE_UNLOCK(ck_spinlock, &spinlock); /* Lock-unlock spinlock in an adaptive manner. */ CK_ELIDE_LOCK_ADAPTIVE(ck_spinlock, &spinlock_stat, &spinlock_config, &spinlock); CK_ELIDE_UNLOCK_ADAPTIVE(ck_spinlock, &spinlock_stat, &spinlock_config, &spinlock); } In this example, user-defined locking functions are provided an elision implementation. /* Assume lock_t has been previously defined. */ #include <ck_elide.h> /* * This function returns true if the lock is unavailable at the time * it was called or false if the lock is available. */ bool is_locked(lock_t *); /* * This function acquires the supplied lock. */ void lock(lock_t *); /* * This function releases the lock. */ void unlock(lock_t *); CK_ELIDE_PROTOTYPE(my_lock, lock_t, is_locked, lock, is_locked, unlock) static lock_t lock; void function(void) { CK_ELIDE_LOCK(my_lock, &lock); CK_ELIDE_UNLOCK(my_lock, &lock); } SEE ALSOck_rwlock(3), ck_spinlock(3)Ravi Rajwar and James R. Goodman. 2001. Speculative lock elision: enabling highly concurrent multithreaded execution. In Proceedings of the 34th annual ACM/IEEE international symposium on Microarchitecture (MICRO 34). IEEE Computer Society, Washington, DC, USA, 294-305. Additional information available at http://en.wikipedia.org/wiki/Transactional_Synchronization_Extensions and http://concurrencykit.org/
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