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NAME ck_spinlock_init, ck_spinlock_lock, ck_spinlock_unlock, ck_spinlock_locked, ck_spinlock_trylock, ck_spinlock_anderson_init, ck_spinlock_anderson_locked, ck_spinlock_anderson_lock, ck_spinlock_anderson_unlock, ck_spinlock_cas_init, ck_spinlock_cas_locked, ck_spinlock_cas_lock, ck_spinlock_cas_lock_eb, ck_spinlock_cas_trylock, ck_spinlock_cas_unlock, ck_spinlock_clh_init, ck_spinlock_clh_locked, ck_spinlock_clh_lock, ck_spinlock_clh_unlock, ck_spinlock_dec_init, ck_spinlock_dec_locked, ck_spinlock_dec_lock, ck_spinlock_dec_lock_eb, ck_spinlock_dec_trylock, ck_spinlock_dec_unlock, ck_spinlock_fas_init, ck_spinlock_fas_lock, ck_spinlock_fas_lock_eb, ck_spinlock_fas_locked, ck_spinlock_fas_trylock, ck_spinlock_fas_unlock, ck_spinlock_hclh_init, ck_spinlock_hclh_locked, ck_spinlock_hclh_lock, ck_spinlock_hclh_unlock, ck_spinlock_mcs_init, ck_spinlock_mcs_locked, ck_spinlock_mcs_lock, ck_spinlock_mcs_trylock, ck_spinlock_mcs_unlock, ck_spinlock_ticket_init, ck_spinlock_ticket_locked, ck_spinlock_ticket_lock, ck_spinlock_ticket_lock_pb, ck_spinlock_ticket_trylock, ck_spinlock_ticket_unlock -- spinlock implementations LIBRARY Concurrency Kit (libck, -lck) SYNOPSIS #include <ck_spinlock.h> ck_spinlock_t spinlock = CK_SPINLOCK_INITIALIZER; void ck_spinlock_init(ck_spinlock_t *lock); void ck_spinlock_lock(ck_spinlock_t *lock); void ck_spinlock_unlock(ck_spinlock_t *lock); bool ck_spinlock_locked(ck_spinlock_t *lock); bool ck_spinlock_trylock(ck_spinlock_t *lock); void ck_spinlock_anderson_init(ck_spinlock_anderson_t *lock, ck_spinlock_anderson_thread_t *slots, unsigned int count); bool ck_spinlock_anderson_locked(ck_spinlock_anderson_t *lock); void ck_spinlock_anderson_lock(ck_spinlock_anderson_t *lock, ck_spinlock_anderson_thread_t **slot); void ck_spinlock_anderson_unlock(ck_spinlock_anderson_t *lock, ck_spinlock_anderson_thread_t *slot); ck_spinlock_cas_t spinlock = CK_SPINLOCK_CAS_INITIALIZER; void ck_spinlock_cas_init(ck_spinlock_cas_t *lock); bool ck_spinlock_cas_locked(ck_spinlock_cas_t *lock); void ck_spinlock_cas_lock(ck_spinlock_cas_t *lock); void ck_spinlock_cas_lock_eb(ck_spinlock_cas_t *lock); bool ck_spinlock_cas_trylock(ck_spinlock_cas_t *lock); void ck_spinlock_cas_unlock(ck_spinlock_cas_t *lock); void ck_spinlock_clh_init(ck_spinlock_clh_t **lock, ck_spinlock_clh_t *unowned); bool ck_spinlock_clh_locked(ck_spinlock_clh_t **lock); void ck_spinlock_clh_lock(ck_spinlock_clh_t **lock, ck_spinlock_clh_t *node); void ck_spinlock_clh_unlock(ck_spinlock_clh_t **node); ck_spinlock_dec_t spinlock = CK_SPINLOCK_DEC_INITIALIZER; void ck_spinlock_dec_init(ck_spinlock_dec_t *lock); bool ck_spinlock_dec_locked(ck_spinlock_dec_t *lock); void ck_spinlock_dec_lock(ck_spinlock_dec_t *lock); void ck_spinlock_dec_lock_eb(ck_spinlock_dec_t *lock); bool ck_spinlock_dec_trylock(ck_spinlock_dec_t *lock); void ck_spinlock_dec_unlock(ck_spinlock_dec_t *lock); ck_spinlock_fas_t spinlock = CK_SPINLOCK_FAS_INITIALIZER; void ck_spinlock_fas_init(ck_spinlock_fas_t *lock); void ck_spinlock_fas_lock(ck_spinlock_fas_t *lock); void ck_spinlock_fas_lock_eb(ck_spinlock_fas_t *lock); bool ck_spinlock_fas_locked(ck_spinlock_fas_t *lock); bool ck_spinlock_fas_trylock(ck_spinlock_fas_t *lock); void ck_spinlock_fas_unlock(ck_spinlock_fas_t *lock); void ck_spinlock_hclh_init(ck_spinlock_hclh_t **lock, ck_spinlock_hclh_t *unowned); bool ck_spinlock_hclh_locked(ck_spinlock_hclh_t **lock); void ck_spinlock_hclh_lock(ck_spinlock_hclh_t **lock, ck_spinlock_hclh_t *node); void ck_spinlock_hclh_unlock(ck_spinlock_hclh_t **node); ck_spinlock_mcs_t spinlock = CK_SPINLOCK_MCS_INITIALIZER; void ck_spinlock_mcs_init(ck_spinlock_mcs_t **lock); bool ck_spinlock_mcs_locked(ck_spinlock_mcs_t **lock); void ck_spinlock_mcs_lock(ck_spinlock_mcs_t **lock, ck_spinlock_mcs_t *node); bool ck_spinlock_mcs_trylock(ck_spinlock_mcs_t **lock, ck_spinlock_mcs_t *node); void ck_spinlock_mcs_unlock(ck_spinlock_mcs_t **lock, ck_spinlock_mcs_t *node); ck_spinlock_ticket_t spinlock = CK_SPINLOCK_TICKET_INITIALIZER; void ck_spinlock_ticket_init(ck_spinlock_ticket_t *lock); bool ck_spinlock_ticket_locked(ck_spinlock_ticket_t *lock); void ck_spinlock_ticket_lock(ck_spinlock_ticket_t *lock); void ck_spinlock_ticket_lock_pb(ck_spinlock_ticket_t *lock, unsigned int period); bool ck_spinlock_ticket_trylock(ck_spinlock_ticket_t *lock); void ck_spinlock_ticket_unlock(ck_spinlock_ticket_t *lock); DESCRIPTION A family of busy-wait spinlock implementations. The ck_spinlock_t implemen- tation is simply a wrapper around the fetch-and-swap (ck_spinlock_fas_t) implementation. The table below provides a summary of the current implemen- tations. | Namespace | Algorithm | Type | Restrictions | Fair | '----------------------|-----------------------------|---------------|-------------------------|--------' ck_spinlock_anderson Anderson Array Fixed number of threads Yes ck_spinlock_cas Compare-and-Swap Centralized None No ck_spinlock_clh Craig, Landin and Hagersten Queue Lifetime requirements Yes ck_spinlock_dec Decrement (Linux kernel) Centralized UINT_MAX concurrency No ck_spinlock_fas Fetch-and-store Centralized None No ck_spinlock_hclh Hierarchical CLH Queue Lifetime requirements Yes * ck_spinlock_mcs Mellor-Crummey and Scott Queue None Yes ck_spinlock_ticket Ticket Centralized None Yes * Hierarchical CLH only offers weak fairness for threads accross cluster nodes. If contention is low and there is no hard requirement for starvation-free- dom then a centralized greedy (unfair) spinlock is recommended. If con- tention is high and there is no requirement for starvation-freedom then a centralized greedy spinlock is recommended to be used with an exponential backoff mechanism. If contention is generally low and there is a hard re- quirement for starvation-freedom then the ticket lock is recommended. If contention is high and there is a hard requirement for starvation-freedom then the Craig and Landin and Hagersten queue spinlock is recommended un- less stack allocation is necessary or NUMA factor is high, in which case the Mellor-Crummey and Scott spinlock is recommended. If you cannot afford O(n) space-usage from array or queue spinlocks but still require fairness under high contention then the ticket lock with proportional back-off is recommended. If NUMA factor is high but prefer a greedy lock, then please see ck_cohort(3). EXAMPLE #include <ck_spinlock.h> #include <stdbool.h> /* * Alternatively, the mutex may be initialized at run-time with * ck_spinlock_init(&mutex). */ ck_spinlock_t mutex = CK_SPINLOCK_INITIALIZER; void example(void) { ck_spinlock_lock(&mutex); /* * Critical section. */ ck_spinlock_unlock(&mutex); ck_spinlock_lock_eb(&mutex); /* * Critical section. */ ck_spinlock_unlock(&mutex); if (ck_spinlock_trylock(&mutex) == true) { /* * Critical section. */ ck_spinlock_unlock(&mutex); } } SEE ALSO ck_cohort(3), ck_elide(3) Additional information available at http://concurrencykit.org/ July 26, 2013. ck_spinlock(3)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | EXAMPLE | SEE ALSO
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