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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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1
libc/sysv/consts.sh
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@ -227,7 +227,6 @@ syscon mmap MAP_LOCKED 0x00002000 0x00002000 0 0 0 0 0 0
syscon mmap MAP_NORESERVE 0x00004000 0x00004000 0x00000040 0x00000040 0 0 0x00000040 0 # Linux calls it "reserve"; NT calls it "commit"? which is default?
syscon mmap MAP_POPULATE 0x00008000 0x00008000 0 0 0x00040000 0 0 0 # MAP_PREFAULT_READ on FreeBSD; can avoid madvise(MADV_WILLNEED) on private file mapping
syscon mmap MAP_NONBLOCK 0x00010000 0x00010000 0 0 0 0 0 0
syscon mmap MAP_NOFORK 0 0 0 0 0 0 0 0x10000000 # used on pages internal to our mmap() implemention on windows
syscon mmap MAP_SYNC 0x00080000 0x00080000 0 0 0 0 0 0 # perform synchronous page faults for mapping (Linux 4.15+)
syscon mmap MAP_HUGETLB 0x00040000 -1 -1 -1 -1 -1 -1 -1 # make it inherit across execve()
syscon mmap MAP_INHERIT -1 -1 -1 -1 -1 -1 0x00000080 -1 # make it inherit across execve()

2
libc/sysv/consts/MAP_NOFORK.S
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@ -1,2 +0,0 @@
#include "libc/sysv/consts/syscon.internal.h"
.syscon mmap,MAP_NOFORK,0,0,0,0,0,0,0,0x10000000

1
libc/sysv/consts/map.h
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@ -19,7 +19,6 @@ extern const int MAP_JIT;
extern const int MAP_LOCKED;
extern const int MAP_NOCACHE;
extern const int MAP_NOEXTEND;
extern const int MAP_NOFORK;
extern const int MAP_NONBLOCK;
extern const int MAP_NORESERVE;
extern const int MAP_NOSYNC;

8
libc/sysv/hostos.S
View file

@ -22,4 +22,10 @@
.balign 8
__hostos:
.quad 0
.endfn __hostos,globl
.endobj __hostos,globl
__tls_index:
.long 0
.endobj __tls_index,globl
__tls_enabled:
.long 0
.endobj __tls_enabled,globl