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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
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GPG key ID: BE714B4575D6E328
71 changed files with 1301 additions and 640 deletions
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13
libc/intrin/maps.h
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@ -18,8 +18,7 @@ struct Map {
int flags; /* memory map flag */
bool iscow; /* windows nt only */
bool readonlyfile; /* windows nt only */
unsigned visited; /* used for checks */
unsigned oldprot; /* in windows fork */
unsigned visited; /* checks and fork */
intptr_t hand; /* windows nt only */
union {
struct Tree tree;
@ -33,7 +32,7 @@ struct Maps {
struct Dll *free;
size_t count;
size_t pages;
atomic_ulong rollo;
atomic_size_t rollo;
struct Map stack;
struct Map guard;
};
@ -45,6 +44,7 @@ struct AddrSize {
extern struct Maps __maps;
void *randaddr(void);
void __maps_init(void);
bool __maps_lock(void);
void __maps_check(void);
@ -52,6 +52,7 @@ void __maps_unlock(void);
void __maps_add(struct Map *);
void __maps_free(struct Map *);
struct Map *__maps_alloc(void);
struct Map *__maps_ceil(const char *);
struct Map *__maps_floor(const char *);
void __maps_stack(char *, int, int, size_t, int, intptr_t);
int __maps_compare(const struct Tree *, const struct Tree *);
@ -61,11 +62,7 @@ forceinline optimizespeed int __maps_search(const void *key,
const struct Tree *node) {
const char *addr = (const char *)key;
const struct Map *map = (const struct Map *)MAP_TREE_CONTAINER(node);
if (addr < map->addr)
return +1;
if (addr >= map->addr + map->size)
return -1;
return 0;
return (addr > map->addr) - (addr < map->addr);
}
static struct Map *__maps_next(struct Map *map) {