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Make dlmalloc 2.4x faster for multithreading

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This change adds a TLS freelist for small dynamic memory allocations.
Cosmopolitan's TIB is now 512 bytes in size. Single-threaded malloc()
performance isn't impacted by this, until pthread_create() is called.
Single-threaded programs may also want to consider using:

    #include "libc/mem/tinymalloc.inc"

Which will shave 30k off the executable size and sometimes go faster.
This commit is contained in:
Justine Tunney 2024-05-28 11:13:12 -07:00
parent deaef81463
commit 07cef612c3
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GPG key ID: BE714B4575D6E328
9 changed files with 150 additions and 6 deletions
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47
third_party/dlmalloc/dlmalloc.c vendored
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@ -23,6 +23,7 @@
#include "libc/thread/thread.h"
#include "libc/thread/tls.h"
#include "third_party/dlmalloc/vespene.internal.h"
#include "libc/thread/tls.h"
#include "third_party/nsync/mu.h"
#define FOOTERS 0
@ -584,7 +585,30 @@ static void* tmalloc_small(mstate m, size_t nb) {
#if !ONLY_MSPACES
#define FREEBIE_COUNT 32
#define FREEBIE_MAXSIZE 2048
void* dlmalloc(size_t bytes) {
#if FREEBIE_COUNT && !defined(MODE_DBG)
/* Allocate from thread-local freelist. */
if (__threaded && bytes && bytes <= FREEBIE_MAXSIZE) {
unsigned need = bytes;
unsigned best_index = FREEBIE_COUNT;
unsigned best_delta = FREEBIE_MAXSIZE + 1;
struct CosmoTib *tib = __get_tls();
for (int i = 0; i < FREEBIE_COUNT; ++i) {
unsigned d = tib->tib_freelen[i] - need;
best_index = d < best_delta ? i : best_index;
best_delta = d < best_delta ? d : best_delta;
}
if (best_index < FREEBIE_COUNT) {
tib->tib_freelen[best_index] = 0;
return tib->tib_freemem[best_index];
}
}
#endif
/*
Basic algorithm:
If a small request (< 256 bytes minus per-chunk overhead):
@ -733,7 +757,6 @@ void dlfree(void* mem) {
free chunks, if they exist, and then place in a bin. Intermixed
with special cases for top, dv, mmapped chunks, and usage errors.
*/
if (mem != 0) {
mchunkptr p = mem2chunk(mem);
#if FOOTERS
@ -745,6 +768,28 @@ void dlfree(void* mem) {
#else /* FOOTERS */
#define fm gm
#endif /* FOOTERS */
#if FREEBIE_COUNT && !defined(MODE_DBG)
/* Free small allocations locally. */
if (__threaded) {
struct CosmoTib *tib = __get_tls();
for (int i = 0; i < FREEBIE_COUNT; ++i) {
if (!tib->tib_freelen[i]) {
if (is_inuse(p)) {
size_t len = chunksize(p) - overhead_for(p);
if (len && len < FREEBIE_MAXSIZE) {
tib->tib_freelen[i] = len;
tib->tib_freemem[i] = mem;
return;
}
}
break;
}
}
}
#endif
/* Otherwise free memory globally. */
if (!PREACTION(fm)) {
check_inuse_chunk(fm, p);
if (RTCHECK(ok_address(fm, p) && ok_inuse(p))) {