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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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36
libc/intrin/writeprocessmemory.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2024 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ 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/strace.h"
#include "libc/nt/memory.h"
#include "libc/nt/thunk/msabi.h"
__msabi extern typeof(WriteProcessMemory) *const __imp_WriteProcessMemory;
bool32 WriteProcessMemory(int64_t hProcess, void *lpBaseAddress,
const void *lpBuffer, uint64_t nSize,
uint64_t *opt_out_lpNumberOfBytesWritten) {
bool32 ok = __imp_WriteProcessMemory(hProcess, lpBaseAddress, lpBuffer, nSize,
opt_out_lpNumberOfBytesWritten);
if (!ok)
__winerr();
NTTRACE("WriteProcessMemory(%ld, %p, %p, %'lu, %p) → %hhhd% m", hProcess,
lpBaseAddress, lpBuffer, nSize, opt_out_lpNumberOfBytesWritten, ok);
return ok;
}