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Make fork() go 30% faster

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This change makes fork() go nearly as fast as sys_fork() on UNIX. As for
Windows this change shaves about 4-5ms off fork() + wait() latency. This
is accomplished by using WriteProcessMemory() from the parent process to
setup the address space of a suspended process; it is better than a pipe
This commit is contained in:
Justine Tunney 2025-01-01 04:59:38 -08:00
parent 98c5847727
commit 0b3c81dd4e
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GPG key ID: BE714B4575D6E328
44 changed files with 769 additions and 649 deletions
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13
libc/intrin/pthread_mutex_wipe_np.c
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@ -16,6 +16,7 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/atomic.h"
#include "libc/str/str.h"
#include "libc/thread/lock.h"
#include "libc/thread/posixthread.internal.h"
@ -25,11 +26,13 @@
* Unlocks mutex from child process after fork.
*/
int _pthread_mutex_wipe_np(pthread_mutex_t *mutex) {
void *edges = mutex->_edges;
uint64_t word = mutex->_word;
bzero(mutex, sizeof(*mutex));
mutex->_word = MUTEX_UNLOCK(word);
mutex->_edges = edges;
atomic_init(&mutex->_word, MUTEX_UNLOCK(atomic_load_explicit(
&mutex->_word, memory_order_relaxed)));
atomic_init(&mutex->_futex, 0);
mutex->_pid = 0;
mutex->_nsync[0] = 0;
atomic_signal_fence(memory_order_relaxed); // avoid xmm
mutex->_nsync[1] = 0;
return 0;
}