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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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30
libc/runtime/winmain.greg.c
View file

@ -52,6 +52,7 @@
#include "libc/sock/internal.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/prot.h"
#include "libc/thread/tls.h"
#ifdef __x86_64__
#define abi __msabi textwindows dontinstrument
@ -87,11 +88,15 @@ void __stack_call(int, char **, char **, long (*)[2],
void (*)(int, char **, char **, long (*)[2]),
intptr_t) wontreturn;
bool __winmain_isfork;
intptr_t __winmain_jmpbuf[5];
struct CosmoTib *__winmain_tib;
__funline int IsAlpha(int c) {
return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
}
static abi char16_t *StrStr(const char16_t *haystack, const char16_t *needle) {
abi static char16_t *StrStr(const char16_t *haystack, const char16_t *needle) {
size_t i;
for (;;) {
for (i = 0;; ++i) {
@ -108,13 +113,13 @@ static abi char16_t *StrStr(const char16_t *haystack, const char16_t *needle) {
return 0;
}
static abi void PrintError(const char *s, size_t n) {
abi static void PrintError(const char *s, size_t n) {
#define PrintError(s) PrintError(s, sizeof(s) - 1)
__imp_WriteFile(__imp_GetStdHandle(kNtStdErrorHandle), s, n, 0, 0);
}
// detect the unholiest of environments
static abi bool32 IsWslChimera(void) {
abi static bool32 IsWslChimera(void) {
char16_t path[PATH_MAX];
return __imp_GetCurrentDirectoryW(PATH_MAX, path) && //
path[0] == '\\' && //
@ -125,7 +130,7 @@ static abi bool32 IsWslChimera(void) {
}
// returns true if utf-8 path is a win32-style path that exists
static abi bool32 WinFileExists(const char *path) {
abi static bool32 WinFileExists(const char *path) {
uint16_t path16[PATH_MAX];
size_t z = ARRAYLEN(path16);
size_t n = tprecode8to16(path16, z, path).ax;
@ -135,7 +140,7 @@ static abi bool32 WinFileExists(const char *path) {
}
// this ensures close(1) won't accidentally close(2) for example
static abi void DeduplicateStdioHandles(void) {
abi static void DeduplicateStdioHandles(void) {
for (long i = 0; i < 3; ++i) {
int64_t h1 = __imp_GetStdHandle(kNtStdio[i]);
for (long j = i + 1; j < 3; ++j) {
@ -150,19 +155,19 @@ static abi void DeduplicateStdioHandles(void) {
}
}
static bool32 HasEnvironmentVariable(const char16_t *name) {
abi static bool32 HasEnvironmentVariable(const char16_t *name) {
char16_t buf[4];
return __imp_GetEnvironmentVariableW(name, buf, ARRAYLEN(buf));
}
static abi unsigned OnWinCrash(struct NtExceptionPointers *ep) {
abi static unsigned OnWinCrash(struct NtExceptionPointers *ep) {
int code, sig = __sig_crash_sig(ep->ExceptionRecord->ExceptionCode, &code);
TerminateThisProcess(sig);
}
// main function of windows init process
// i.e. first process spawned that isn't forked
static abi wontreturn void WinInit(const char16_t *cmdline) {
abi wontreturn static void WinInit(const char16_t *cmdline) {
__oldstack = (intptr_t)__builtin_frame_address(0);
__imp_SetConsoleOutputCP(kNtCpUtf8);
@ -314,7 +319,7 @@ static int Atoi(const char16_t *str) {
return x;
}
static abi int WinGetPid(const char16_t *var, bool *out_is_inherited) {
abi static int WinGetPid(const char16_t *var, bool *out_is_inherited) {
uint32_t len;
char16_t val[12];
if ((len = __imp_GetEnvironmentVariableW(var, val, ARRAYLEN(val)))) {
@ -338,6 +343,8 @@ abi int64_t WinMain(int64_t hInstance, int64_t hPrevInstance,
extern char os asm("__hostos");
os = _HOSTWINDOWS; // madness https://news.ycombinator.com/item?id=21019722
kStartTsc = rdtsc();
__tls_enabled = false;
ftrace_enabled(-1);
if (!IsTiny() && IsWslChimera()) {
PrintError("error: APE is running on WIN32 inside WSL. You need to run: "
"sudo sh -c 'echo -1 > /proc/sys/fs/binfmt_misc/WSLInterop'\n");
@ -351,6 +358,8 @@ abi int64_t WinMain(int64_t hInstance, int64_t hPrevInstance,
__pid = WinGetPid(u"_COSMO_PID", &pid_is_inherited);
if (!(__sig.process = __sig_map_process(__pid, kNtOpenAlways)))
__sig.process = &fake_process_signals;
if (__winmain_isfork)
__builtin_longjmp(__winmain_jmpbuf, 1);
if (!pid_is_inherited)
atomic_store_explicit(__sig.process, 0, memory_order_release);
cmdline = __imp_GetCommandLineW();
@ -359,11 +368,10 @@ abi int64_t WinMain(int64_t hInstance, int64_t hPrevInstance,
if (StrStr(cmdline, u"--strace"))
++__strace;
#endif
ftrace_enabled(+1);
if (_weaken(WinSockInit))
_weaken(WinSockInit)();
DeduplicateStdioHandles();
if (_weaken(WinMainForked))
_weaken(WinMainForked)();
WinInit(cmdline);
}