mirror/glibc
2
0
Fork 0
mirror of git://sourceware.org/git/glibc.git synced 2025-03-31 14:01:18 +08:00
Code Issues Packages Projects Releases Wiki Activity

malloc: Improve arena_for_chunk()

Browse Source 
Change heap_max_size() to improve performance of arena_for_chunk().
Instead of a complex calculation, using a simple mask operation to get the
arena base pointer.  HEAP_MAX_SIZE should be larger than the huge page size,
otherwise heaps will use not huge pages.

On AArch64 this removes 6 instructions from arena_for_chunk(), and
bench-malloc-thread improves by 1.1% - 1.8%.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Wilco Dijkstra 2025-03-18 12:30:10 +00:00
parent dd003db8d1
commit 9f551e28a7
1 changed files with 7 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
malloc/arena.c
View File

@ -40,19 +40,20 @@
mmap threshold, so that requests with a size just below that
threshold can be fulfilled without creating too many heaps. */
/* When huge pages are used to create new arenas, the maximum and minimum
size are based on the runtime defined huge page size. */
/* HEAP_MAX_SIZE should be larger than the huge page size, otherwise heaps will
use not huge pages. It is a constant so arena_for_chunk() is efficient. */
static inline size_t
heap_min_size (void)
{
return mp_.hp_pagesize == 0 ? HEAP_MIN_SIZE : mp_.hp_pagesize;
return mp_.hp_pagesize == 0 || mp_.hp_pagesize > HEAP_MAX_SIZE
? HEAP_MIN_SIZE : mp_.hp_pagesize;
}
static inline size_t
heap_max_size (void)
{
return mp_.hp_pagesize == 0 ? HEAP_MAX_SIZE : mp_.hp_pagesize * 4;
return HEAP_MAX_SIZE;
}
/***************************************************************************/
@ -313,7 +314,7 @@ ptmalloc_init (void)
TUNABLE_GET (mxfast, size_t, TUNABLE_CALLBACK (set_mxfast));
TUNABLE_GET (hugetlb, size_t, TUNABLE_CALLBACK (set_hugetlb));
if (mp_.hp_pagesize > 0)
if (mp_.hp_pagesize > 0 && mp_.hp_pagesize <= heap_max_size ())
{
/* Force mmap for main arena instead of sbrk, so MAP_HUGETLB is always
tried. Also tune the mmap threshold, so allocation smaller than the
@ -460,7 +461,7 @@ alloc_new_heap (size_t size, size_t top_pad, size_t pagesize,
static heap_info *
new_heap (size_t size, size_t top_pad)
{
if (__glibc_unlikely (mp_.hp_pagesize != 0))
if (mp_.hp_pagesize != 0 && mp_.hp_pagesize <= heap_max_size ())
{
heap_info *h = alloc_new_heap (size, top_pad, mp_.hp_pagesize,
mp_.hp_flags);