lib/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2025-07-29 11:41:21 +03:00
Code Activity

malloc: Improve performance of __libc_calloc

Browse Source 
Improve performance of __libc_calloc by splitting it into 2 parts: first handle
the tcache fastpath, then do the rest in a separate tailcalled function.
This results in significant performance gains since __libc_calloc doesn't need
to setup a frame.

On Neoverse V2, bench-calloc-simple improves by 5.0% overall.
Bench-calloc-thread 1 improves by 24%.

Reviewed-by: DJ Delorie <dj@redhat.com>
This commit is contained in:
Wilco Dijkstra
2025-05-09 16:02:14 +00:00
parent 0fc76d8762
commit 36189c76fb
1 changed files with 43 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

70
malloc/malloc.c
View File

@ -591,6 +591,8 @@ tag_at (void *ptr)
void* __libc_malloc(size_t);
libc_hidden_proto (__libc_malloc)
static void *__libc_calloc2 (size_t);
/*
free(void* p)
Releases the chunk of memory pointed to by p, that had been previously
@ -3324,6 +3326,13 @@ tcache_init(void)
}
static void * __attribute_noinline__
tcache_calloc_init (size_t bytes)
{
tcache_init ();
return __libc_calloc2 (bytes);
}
# define MAYBE_INIT_TCACHE() \
if (__glibc_unlikely (tcache == NULL)) \
tcache_init();
@ -3711,38 +3720,13 @@ __libc_pvalloc (size_t bytes)
}
void *
__libc_calloc (size_t n, size_t elem_size)
__libc_calloc2 (size_t sz)
{
mstate av;
mchunkptr oldtop, p;
INTERNAL_SIZE_T sz, oldtopsize, csz;
INTERNAL_SIZE_T oldtopsize, csz;
void *mem;
unsigned long clearsize;
ptrdiff_t bytes;
if (__glibc_unlikely (__builtin_mul_overflow (n, elem_size, &bytes)))
{
__set_errno (ENOMEM);
return NULL;
}
sz = bytes;
#if USE_TCACHE
size_t tc_idx = usize2tidx (bytes);
if (tcache_available (tc_idx))
{
mem = tcache_get (tc_idx);
p = mem2chunk (mem);
if (__glibc_unlikely (mtag_enabled))
return tag_new_zero_region (mem, memsize (p));
csz = chunksize (p);
clearsize = csz - SIZE_SZ;
return clear_memory ((INTERNAL_SIZE_T *) mem, clearsize);
}
MAYBE_INIT_TCACHE ();
#endif
if (SINGLE_THREAD_P)
av = &main_arena;
@ -3828,6 +3812,38 @@ __libc_calloc (size_t n, size_t elem_size)
clearsize = csz - SIZE_SZ;
return clear_memory ((INTERNAL_SIZE_T *) mem, clearsize);
}
void *
__libc_calloc (size_t n, size_t elem_size)
{
size_t bytes;
if (__glibc_unlikely (__builtin_mul_overflow (n, elem_size, &bytes)))
{
__set_errno (ENOMEM);
return NULL;
}
#if USE_TCACHE
size_t tc_idx = usize2tidx (bytes);
if (__glibc_likely (tc_idx < mp_.tcache_bins))
{
if (__glibc_unlikely (tcache == NULL))
return tcache_calloc_init (bytes);
if (__glibc_likely (tcache->entries[tc_idx] != NULL))
{
void *mem = tcache_get (tc_idx);
if (__glibc_unlikely (mtag_enabled))
return tag_new_zero_region (mem, memsize (mem2chunk (mem)));
return clear_memory ((INTERNAL_SIZE_T *) mem, tidx2usize (tc_idx));
}
}
#endif
return __libc_calloc2 (bytes);
}
#endif /* IS_IN (libc) */
/*