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Make improvements to locking

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This change makes pthread_mutex_lock() as fast as _spinlock() by
default. Thread instability issues on NetBSD have been resolved.
Improvements made to gdtoa thread code. Crash reporting will now
synchronize between threads in a slightly better way.
This commit is contained in:
Justine Tunney 2022-06-19 01:13:03 -07:00
parent 25041b8026
commit d5312b60f7
60 changed files with 890 additions and 629 deletions
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79
libc/intrin/pthread_mutex_lock.c
View file

@ -21,41 +21,68 @@
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/pthread.h"
#include "libc/intrin/spinlock.h"
#include "libc/linux/futex.h"
#include "libc/nexgen32e/threaded.h"
static int pthread_mutex_lock_spin(pthread_mutex_t *mutex, int tries) {
volatile int i;
if (tries < 7) {
for (i = 0; i != 1 << tries; i++) {
}
tries++;
} else if (IsLinux()) {
atomic_fetch_add(&mutex->waits, 1);
LinuxFutexWait(&mutex->lock, 1, 0);
atomic_fetch_sub(&mutex->waits, 1);
} else {
sched_yield();
}
return tries;
}
/**
* Locks mutex.
*
* _spinlock() l: 181,570c 58,646ns
* mutex normal l: 297,965c 96,241ns
* mutex recursive l: 1,112,166c 359,223ns
* mutex errorcheck l: 1,449,723c 468,252ns
*
* @return 0 on success, or error number on failure
*/
int pthread_mutex_lock(pthread_mutex_t *mutex) {
volatile int i;
int(pthread_mutex_lock)(pthread_mutex_t *mutex) {
int me, owner, tries;
for (tries = 0, me = gettid();;) {
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) {
break;
} else {
return EDEADLK;
switch (mutex->attr) {
case PTHREAD_MUTEX_NORMAL:
for (tries = 0;;) {
if (!atomic_load_explicit(&mutex->lock, memory_order_relaxed) &&
!atomic_exchange_explicit(&mutex->lock, 1, memory_order_acquire)) {
break;
}
tries = pthread_mutex_lock_spin(mutex, tries);
}
}
if (tries < 7) {
for (i = 0; i != 1 << tries; i++) {
return 0;
case PTHREAD_MUTEX_RECURSIVE:
case PTHREAD_MUTEX_ERRORCHECK:
for (tries = 0, me = gettid();;) {
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) {
break;
} else {
return EDEADLK;
}
}
tries = pthread_mutex_lock_spin(mutex, tries);
}
tries++;
} else if (IsLinux()) {
atomic_fetch_add(&mutex->waits, 1);
LinuxFutexWait(&mutex->lock, owner, 0);
atomic_fetch_sub(&mutex->waits, 1);
} else {
sched_yield();
}
++mutex->reent;
return 0;
default:
return EINVAL;
}
++mutex->reent;
return 0;
}