diff mbox series

[v3,3/5] malloc: Arena is not needed for tcache path in free()

Message ID 20240829062732.1663342-4-wangyang.guo@intel.com
State Under Review
Delegated to: Florian Weimer
Headers
Series malloc: TCACHE improvement for free and calloc |

Checks

Context Check Description
redhat-pt-bot/TryBot-apply_patch success Patch applied to master at the time it was sent
linaro-tcwg-bot/tcwg_glibc_build--master-arm success Build passed
linaro-tcwg-bot/tcwg_glibc_build--master-aarch64 success Build passed
linaro-tcwg-bot/tcwg_glibc_check--master-arm success Test passed
linaro-tcwg-bot/tcwg_glibc_check--master-aarch64 success Test passed

Commit Message

Guo, Wangyang Aug. 29, 2024, 6:27 a.m. UTC 
  Arena is not needed for _int_free_check() in non-DEBUG mode. This commit
defers arena deference to _int_free_chunk() thus accelerate tcache path.
When DEBUG enabled, arena can be obtained from p in do_check_inuse_chunk().

Result of bench-malloc-thread benchmark

Test Platform: Xeon-8380
Ratio: New / Original time_per_iteration (Lower is Better)

Threads#   | Ratio
-----------|------
1 thread   | 0.994
4 threads  | 0.968

The data shows it can brings 3% performance gain in multi-thread scenario.

---
Changes in v2:
- _int_free_check() should be put outside of USE_TCACHE.
- Link to v1: https://sourceware.org/pipermail/libc-alpha/2024-August/159360.html
---
 malloc/malloc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/malloc/malloc.c b/malloc/malloc.c
index 264f35e1a3..efb5292e9f 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -2143,6 +2143,9 @@  do_check_inuse_chunk (mstate av, mchunkptr p)
 {
   mchunkptr next;
 
+  if (av == NULL)
+    av = arena_for_chunk (p);
+
   do_check_chunk (av, p);
 
   if (chunk_is_mmapped (p))
@@ -3447,9 +3450,10 @@  __libc_free (void *mem)
       /* Mark the chunk as belonging to the library again.  */
       (void)tag_region (chunk2mem (p), memsize (p));
 
-      ar_ptr = arena_for_chunk (p);
       INTERNAL_SIZE_T size = chunksize (p);
-      _int_free_check (ar_ptr, p, size);
+      /* av is not needed for _int_free_check in non-DEBUG mode,
+	 in DEBUG mode, av will fetch from p in do_check_inuse_chunk.  */
+      _int_free_check (NULL, p, size);
 
 #if USE_TCACHE
       if (tcache_free (p, size))
@@ -3458,6 +3462,8 @@  __libc_free (void *mem)
 	  return;
 	}
 #endif
+
+      ar_ptr = arena_for_chunk (p);
       _int_free_chunk (ar_ptr, p, size, 0);
     }