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Write some lock contention tests

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This commit is contained in:
Justine Tunney 2022-06-16 09:06:09 -07:00
parent 42c38bc3e3
commit c06ffd458c
19 changed files with 205 additions and 76 deletions
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25
libc/intrin/pthread_mutex_lock.c
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@ -29,11 +29,12 @@
* @return 0 on success, or error number on failure
*/
int pthread_mutex_lock(pthread_mutex_t *mutex) {
int me, owner;
unsigned tries;
int i, me, owner, tries;
for (tries = 0, me = gettid();;) {
owner = 0;
if (atomic_compare_exchange_strong(&mutex->owner, &owner, me)) {
owner = atomic_load_explicit(&mutex->lock, memory_order_relaxed);
if (!owner && atomic_compare_exchange_weak_explicit(
&mutex->lock, &owner, me, memory_order_acquire,
memory_order_relaxed)) {
break;
} else if (owner == me) {
if (mutex->attr != PTHREAD_MUTEX_ERRORCHECK) {
@ -42,15 +43,17 @@ int pthread_mutex_lock(pthread_mutex_t *mutex) {
return EDEADLK;
}
}
atomic_fetch_add(&mutex->waits, 1);
if (!IsLinux() || LinuxFutexWait((void *)&mutex->owner, owner, 0)) {
if (++tries & 7) {
__builtin_ia32_pause();
} else {
sched_yield();
if (tries < 7) {
for (i = 0; i != 1 << tries; i++) {
}
tries++;
} else if (IsLinux()) {
atomic_fetch_add(&mutex->waits, 1);
LinuxFutexWait(&mutex->lock, owner, 0);
atomic_fetch_sub(&mutex->waits, 1);
} else {
sched_yield();
}
atomic_fetch_sub(&mutex->waits, 1);
}
++mutex->reent;
return 0;