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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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17
libc/intrin/virtualprotect.c
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@ -16,13 +16,8 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/intrin/describeflags.h"
#include "libc/intrin/strace.h"
#include "libc/log/libfatal.internal.h"
#include "libc/nt/memory.h"
__msabi extern typeof(VirtualProtect) *const __imp_VirtualProtect;
#include "libc/nt/runtime.h"
/**
* Protects memory on the New Technology.
@ -31,12 +26,6 @@ __msabi extern typeof(VirtualProtect) *const __imp_VirtualProtect;
textwindows bool32 VirtualProtect(void *lpAddress, uint64_t dwSize,
uint32_t flNewProtect,
uint32_t *lpflOldProtect) {
bool32 bOk;
bOk = __imp_VirtualProtect(lpAddress, dwSize, flNewProtect, lpflOldProtect);
if (!bOk)
__winerr();
NTTRACE("VirtualProtect(%p, %'zu, %s, [%s]) → %hhhd% m", lpAddress, dwSize,
DescribeNtPageFlags(flNewProtect),
DescribeNtPageFlags(*lpflOldProtect), bOk);
return bOk;
return VirtualProtectEx(GetCurrentProcess(), lpAddress, dwSize, flNewProtect,
lpflOldProtect);
}