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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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21
libc/intrin/printmaps.c
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@ -16,6 +16,7 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/dce.h"
#include "libc/fmt/conv.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/bsr.h"
@ -51,13 +52,14 @@ void __print_maps(size_t limit) {
char mappingbuf[8];
struct Map *last = 0;
int pagesz = __pagesize;
int gransz = __gransize;
int digs = get_address_digits(pagesz);
for (struct Tree *e = tree_first(__maps.maps); e; e = tree_next(e)) {
struct Map *map = MAP_TREE_CONTAINER(e);
// show gaps between maps
if (last) {
char *beg = last->addr + ((last->size + pagesz - 1) & -pagesz);
char *beg = last->addr + ((last->size + gransz - 1) & -gransz);
char *end = map->addr;
if (end > beg) {
size_t gap = end - beg;
@ -72,8 +74,21 @@ void __print_maps(size_t limit) {
_DescribeMapping(mappingbuf, map->prot, map->flags));
sizefmt(sb, map->size, 1024);
kprintf(" %!sb", sb);
if (map->hand && map->hand != -1)
kprintf(" hand=%ld", map->hand);
if (IsWindows()) {
switch (map->hand) {
case MAPS_RESERVATION:
kprintf(" reservation");
break;
case MAPS_SUBREGION:
break;
case MAPS_VIRTUAL:
kprintf(" virtual");
break;
default:
kprintf(" hand=%ld", map->hand);
break;
}
}
if (map->iscow)
kprintf(" cow");
if (map->readonlyfile)