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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
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
44 changed files with 769 additions and 649 deletions
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41
libc/intrin/pthread_setcancelstate.c
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@ -47,28 +47,30 @@
* @asyncsignalsafe
*/
errno_t pthread_setcancelstate(int state, int *oldstate) {
int old;
errno_t err;
struct PosixThread *pt;
if (__tls_enabled && (pt = _pthread_self())) {
if (pt->pt_flags & PT_NOCANCEL) {
old = PTHREAD_CANCEL_DISABLE;
} else if (pt->pt_flags & PT_MASKED) {
old = PTHREAD_CANCEL_MASKED;
} else {
old = PTHREAD_CANCEL_ENABLE;
}
switch (state) {
case PTHREAD_CANCEL_ENABLE:
case PTHREAD_CANCEL_DISABLE:
case PTHREAD_CANCEL_MASKED:
if (oldstate) {
if (pt->pt_flags & PT_NOCANCEL) {
*oldstate = PTHREAD_CANCEL_DISABLE;
} else if (pt->pt_flags & PT_MASKED) {
*oldstate = PTHREAD_CANCEL_MASKED;
} else {
*oldstate = PTHREAD_CANCEL_ENABLE;
}
}
pt->pt_flags &= ~(PT_NOCANCEL | PT_MASKED);
if (state == PTHREAD_CANCEL_MASKED) {
pt->pt_flags |= PT_MASKED;
} else if (state == PTHREAD_CANCEL_DISABLE) {
pt->pt_flags |= PT_NOCANCEL;
}
err = 0;
break;
case PTHREAD_CANCEL_DISABLE:
pt->pt_flags &= ~(PT_NOCANCEL | PT_MASKED);
pt->pt_flags |= PT_NOCANCEL;
err = 0;
break;
case PTHREAD_CANCEL_MASKED:
pt->pt_flags &= ~(PT_NOCANCEL | PT_MASKED);
pt->pt_flags |= PT_MASKED;
err = 0;
break;
default:
@ -76,11 +78,12 @@ errno_t pthread_setcancelstate(int state, int *oldstate) {
break;
}
} else {
if (oldstate) {
*oldstate = 0;
}
old = 0;
err = 0;
}
if (!err)
if (oldstate)
*oldstate = old;
#if IsModeDbg() && 0
STRACE("pthread_setcancelstate(%s, [%s]) → %s",
DescribeCancelState(0, &state), DescribeCancelState(err, oldstate),