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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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66
libc/intrin/pthread_atfork_actual.c
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@ -16,21 +16,11 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/atomic.h"
#include "libc/calls/state.internal.h"
#include "libc/cosmo.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/dll.h"
#include "libc/intrin/strace.h"
#include "libc/macros.internal.h"
#include "libc/proc/proc.internal.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/thread.h"
#include "libc/thread/tls.h"
struct AtFork {
struct AtFork *p[2];
@ -38,16 +28,16 @@ struct AtFork {
};
static struct AtForks {
pthread_spinlock_t lock;
pthread_mutex_t lock;
struct AtFork *list;
struct AtFork pool[64];
atomic_int allocated;
} _atforks;
struct AtFork pool[256];
int allocated;
} _atforks = {
PTHREAD_MUTEX_INITIALIZER,
};
static void _pthread_onfork(int i, const char *op) {
struct AtFork *a;
if (!i)
pthread_spin_lock(&_atforks.lock);
for (a = _atforks.list; a; a = a->p[!i]) {
if (a->f[i]) {
STRACE("pthread_atfork(%s, %t)", op, a->f[i]);
@ -55,47 +45,41 @@ static void _pthread_onfork(int i, const char *op) {
}
_atforks.list = a;
}
if (i)
pthread_spin_unlock(&_atforks.lock);
}
void _pthread_onfork_prepare(void) {
pthread_mutex_lock(&_atforks.lock);
_pthread_onfork(0, "prepare");
}
void _pthread_onfork_parent(void) {
_pthread_onfork(1, "parent");
pthread_mutex_unlock(&_atforks.lock);
}
void _pthread_onfork_child(void) {
pthread_mutex_init(&_atforks.lock, 0);
_pthread_onfork(2, "child");
}
static struct AtFork *_pthread_atfork_alloc(void) {
int i, n = ARRAYLEN(_atforks.pool);
if (atomic_load_explicit(&_atforks.allocated, memory_order_relaxed) < n &&
(i = atomic_fetch_add(&_atforks.allocated, 1)) < n) {
return _atforks.pool + i;
} else {
return 0;
}
}
int _pthread_atfork(atfork_f prepare, atfork_f parent, atfork_f child) {
int rc;
struct AtFork *a;
if (!(a = _pthread_atfork_alloc()))
return ENOMEM;
a->f[0] = prepare;
a->f[1] = parent;
a->f[2] = child;
pthread_spin_lock(&_atforks.lock);
a->p[0] = 0;
a->p[1] = _atforks.list;
if (_atforks.list)
_atforks.list->p[0] = a;
_atforks.list = a;
pthread_spin_unlock(&_atforks.lock);
rc = 0;
pthread_mutex_lock(&_atforks.lock);
if (_atforks.allocated < ARRAYLEN(_atforks.pool)) {
a = &_atforks.pool[_atforks.allocated++];
a->f[0] = prepare;
a->f[1] = parent;
a->f[2] = child;
a->p[0] = 0;
a->p[1] = _atforks.list;
if (_atforks.list)
_atforks.list->p[0] = a;
_atforks.list = a;
rc = 0;
} else {
rc = ENOMEM;
}
pthread_mutex_unlock(&_atforks.lock);
return rc;
}