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Make realloc() go 100x faster on Linux/NetBSD

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Cosmopolitan now supports mremap(), which is only supported on Linux and
NetBSD. First, it allows memory mappings to be relocated without copying
them; this can dramatically speed up data structures like std::vector if
the array size grows larger than 256kb. The mremap() system call is also
10x faster than munmap() when shrinking large memory mappings.

There's now two functions, getpagesize() and getgransize() which help to
write portable code that uses mmap(MAP_FIXED). Alternative sysconf() may
be called with our new _SC_GRANSIZE. The madvise() system call now has a
better wrapper with improved documentation.
This commit is contained in:
Justine Tunney 2024-07-07 12:24:25 -07:00
parent 196942084b
commit f7780de24b
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
71 changed files with 1301 additions and 640 deletions
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31
libc/proc/fork-nt.c
View file

@ -71,9 +71,10 @@ extern long __klog_handle;
void WipeKeystrokes(void);
__msabi extern typeof(GetCurrentProcessId) *const __imp_GetCurrentProcessId;
static textwindows wontreturn void AbortFork(const char *func) {
static textwindows wontreturn void AbortFork(const char *func, void *addr) {
#if SYSDEBUG
kprintf("fork() %!s() failed with win32 error %u\n", func, GetLastError());
kprintf("fork() %!s(%lx) failed with win32 error %u\n", func, addr,
GetLastError());
#endif
TerminateThisProcess(SIGSTKFLT);
}
@ -134,9 +135,9 @@ static dontinline textwindows bool WriteAll(int64_t h, void *buf, size_t n) {
static textwindows dontinline void ReadOrDie(int64_t h, void *buf, size_t n) {
ssize_t got;
if ((got = ForkIo2(h, buf, n, ReadFile, "ReadFile", true)) == -1)
AbortFork("ReadFile1");
AbortFork("ReadFile1", buf);
if (got != n)
AbortFork("ReadFile2");
AbortFork("ReadFile2", buf);
}
static textwindows int64_t MapOrDie(uint32_t prot, uint64_t size) {
@ -159,7 +160,7 @@ static textwindows int64_t MapOrDie(uint32_t prot, uint64_t size) {
break;
}
}
AbortFork("MapOrDie");
AbortFork("MapOrDie", (void *)size);
}
}
@ -172,7 +173,7 @@ TryAgain:
access &= ~kNtFileMapExecute;
goto TryAgain;
}
AbortFork("ViewOrDie");
AbortFork("ViewOrDie", base);
}
}
@ -223,7 +224,7 @@ textwindows void WinMainForked(void) {
}
// map memory into process
int granularity = __granularity();
int granularity = getgransize();
for (struct Tree *e = tree_first(maps); e; e = tree_next(e)) {
struct Map *map = MAP_TREE_CONTAINER(e);
if ((uintptr_t)map->addr & (granularity - 1))
@ -280,14 +281,14 @@ textwindows void WinMainForked(void) {
unsigned old_protect;
if (!VirtualProtect(map->addr, map->size, __prot2nt(map->prot, map->iscow),
&old_protect))
AbortFork("VirtualProtect");
AbortFork("VirtualProtect", map->addr);
}
__maps.maps = maps;
__maps_init();
// mitosis complete
if (!CloseHandle(reader))
AbortFork("CloseHandle");
AbortFork("CloseHandle", (void *)reader);
// rewrap the stdin named pipe hack
// since the handles closed on fork
@ -370,6 +371,8 @@ textwindows int sys_fork_nt(uint32_t dwCreationFlags) {
// this list will be populated with the maps we're transferring
for (struct Map *map = __maps_first(); ok && map;
map = __maps_next(map)) {
if (map->flags & MAP_NOFORK)
continue;
if (MAX((char *)__executable_start, map->addr) <
MIN((char *)_end, map->addr + map->size))
continue; // executable image is loaded by windows
@ -382,9 +385,11 @@ textwindows int sys_fork_nt(uint32_t dwCreationFlags) {
ok = WriteAll(writer, &map, sizeof(map));
}
// now write content of each map to child
int granularity = __granularity();
int granularity = getgransize();
for (struct Map *map = __maps_first(); ok && map;
map = __maps_next(map)) {
if (map->flags & MAP_NOFORK)
continue;
// we only need to worry about the base mapping
if ((uintptr_t)map->addr & (granularity - 1))
continue;
@ -410,15 +415,15 @@ textwindows int sys_fork_nt(uint32_t dwCreationFlags) {
ok = VirtualProtect(
map2->addr, map2->size,
__prot2nt(map2->prot | PROT_READ, map2->iscow),
&map2->oldprot);
&map2->visited);
}
if (ok)
ok = WriteAll(writer, map->addr, size);
for (struct Map *map2 = map; ok && map2; map2 = __maps_next(map2)) {
if (!(map2->prot & PROT_READ))
if (map->addr >= map2->addr && map->addr < map->addr + size)
ok = VirtualProtect(map2->addr, map2->size, map2->oldprot,
&map2->oldprot);
ok = VirtualProtect(map2->addr, map2->size, map2->visited,
&map2->visited);
}
}
if (ok)