Author: Remi Meier <[email protected]>
Branch: use-gcc
Changeset: r1937:f3b1d74a2633
Date: 2015-08-17 15:35 +0200
http://bitbucket.org/pypy/stmgc/changeset/f3b1d74a2633/
Log: avoid synchronizing operation in smallmalloc fastpath
Probably doesn't matter much, but change the accounting of allocated
memory to page instead of (small) obj granularity. In a sense, this
is also correct and avoids a synchronizing instruction in the
fastpath of smallmalloc-allocate.
diff --git a/c8/stm/pages.c b/c8/stm/pages.c
--- a/c8/stm/pages.c
+++ b/c8/stm/pages.c
@@ -28,7 +28,7 @@
uint64_t ta = __sync_add_and_fetch(&pages_ctl.total_allocated,
add_or_remove);
- if (ta >= pages_ctl.total_allocated_bound)
+ if (UNLIKELY(ta >= pages_ctl.total_allocated_bound))
pages_ctl.major_collection_requested = true;
return ta;
diff --git a/c8/stm/smallmalloc.c b/c8/stm/smallmalloc.c
--- a/c8/stm/smallmalloc.c
+++ b/c8/stm/smallmalloc.c
@@ -126,12 +126,15 @@
Maybe we can pick one from free_uniform_pages.
*/
smallpage = free_uniform_pages;
- if (smallpage != NULL) {
+ if (LIKELY(smallpage != NULL)) {
if (UNLIKELY(!__sync_bool_compare_and_swap(&free_uniform_pages,
smallpage,
smallpage->nextpage)))
goto retry;
+ /* got a new page: */
+ increment_total_allocated(4096);
+
/* Succeeded: we have a page in 'smallpage', which is not
initialized so far, apart from the 'nextpage' field read
above. Initialize it.
@@ -174,8 +177,6 @@
struct small_free_loc_s *result = *fl;
- increment_total_allocated(size);
-
if (UNLIKELY(result == NULL)) {
char *addr = _allocate_small_slowpath(size);
((struct object_s*)addr)->stm_flags = 0;
@@ -270,7 +271,6 @@
}
else if (!_smallmalloc_sweep_keep(p)) {
/* the location should be freed now */
- increment_total_allocated(-szword*8);
#ifdef STM_TESTS
/* fill location with 0xdd in all segs except seg0 */
int j;
@@ -311,6 +311,9 @@
((struct small_free_loc_s *)baseptr)->nextpage = free_uniform_pages;
free_uniform_pages = (struct small_free_loc_s *)baseptr;
+
+ /* gave the page back */
+ increment_total_allocated(-4096);
}
else if (!any_object_dying) {
get_fpsz(baseptr)->sz = szword;
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