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Make spin locks go faster

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Justine Tunney 2024-07-25 17:14:30 -07:00
parent a31d5ea399
commit c8e25d811c
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GPG key ID: BE714B4575D6E328
16 changed files with 150 additions and 123 deletions
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7
libc/intrin/pthread_mutex_unlock.c
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@ -28,9 +28,8 @@
#include "third_party/nsync/futex.internal.h"
#include "third_party/nsync/mu.h"
static void pthread_mutex_unlock_naive(pthread_mutex_t *mutex, uint64_t word) {
uint64_t lock = MUTEX_UNLOCK(word);
atomic_store_explicit(&mutex->_word, lock, memory_order_release);
static void pthread_mutex_unlock_spin(atomic_int *word) {
atomic_store_explicit(word, 0, memory_order_release);
}
// see "take 3" algorithm in "futexes are tricky" by ulrich drepper
@ -102,7 +101,7 @@ errno_t pthread_mutex_unlock(pthread_mutex_t *mutex) {
if (_weaken(nsync_futex_wake_)) {
pthread_mutex_unlock_drepper(&mutex->_futex, MUTEX_PSHARED(word));
} else {
pthread_mutex_unlock_naive(mutex, word);
pthread_mutex_unlock_spin(&mutex->_futex);
}
return 0;
}