Author: Remi Meier <[email protected]>
Branch: c8-faster-smallobj-sync
Changeset: r1940:01da8e5d803d
Date: 2015-08-17 16:59 +0200
http://bitbucket.org/pypy/stmgc/changeset/01da8e5d803d/
Log: reuse smallobj pages only after they are half-empty again
Again trying to improve the range-merging chance - again failing.
Probably need a completely different strategy if we can improve this
at all. And I should first find more meaningful benchmarks where the
problem really shows up.
diff --git a/c8/stm/smallmalloc.c b/c8/stm/smallmalloc.c
--- a/c8/stm/smallmalloc.c
+++ b/c8/stm/smallmalloc.c
@@ -36,6 +36,7 @@
static void teardown_smallmalloc(void)
{
memset(small_page_lists, 0, sizeof(small_page_lists));
+ memset(pretty_full_pages, 0, sizeof(pretty_full_pages));
assert(free_uniform_pages == NULL); /* done by the previous line */
first_small_uniform_loc = (uintptr_t) -1;
#ifdef STM_TESTS
@@ -261,6 +262,7 @@
to have it ignored in the end because we put the page into
'free_uniform_pages' */
+ long free_slots_balance = 0;
for (i = 0; i <= 4096 - size; i += size) {
char *p = baseptr + i;
if (p == (char *)fl) {
@@ -268,9 +270,11 @@
flprev = fl;
fl = fl->next;
any_object_dying = true;
+ free_slots_balance++;
}
else if (!_smallmalloc_sweep_keep(p)) {
/* the location should be freed now */
+ free_slots_balance++;
#ifdef STM_TESTS
/* fill location with 0xdd in all segs except seg0 */
int j;
@@ -297,6 +301,7 @@
}
else {
//dprintf(("keep small %p : %lu\n", (char*)(p - stm_object_pages),
szword*8));
+ free_slots_balance--;
any_object_remaining = true;
}
}
@@ -322,9 +327,15 @@
get_full_page_size(baseptr)->sz = szword;
}
else {
- check_order_inside_small_page(page_free);
- page_free->nextpage = small_page_lists[szword];
- small_page_lists[szword] = page_free;
+ if (free_slots_balance < 0) {
+ /* "pretty full" */
+ page_free->nextpage = pretty_full_pages[szword];
+ pretty_full_pages[szword] = page_free;
+ } else {
+ check_order_inside_small_page(page_free);
+ page_free->nextpage = small_page_lists[szword];
+ small_page_lists[szword] = page_free;
+ }
}
}
@@ -333,8 +344,10 @@
long i, szword;
for (szword = 2; szword < GC_N_SMALL_REQUESTS; szword++) {
struct small_free_loc_s *page = small_page_lists[szword];
+ struct small_free_loc_s *pfpage = pretty_full_pages[szword];
struct small_free_loc_s *nextpage;
small_page_lists[szword] = NULL;
+ pretty_full_pages[szword] = NULL;
/* process the pages that the various segments are busy filling */
/* including sharing seg0 for old-malloced things */
@@ -362,6 +375,14 @@
sweep_small_page(getbaseptr(page), page, szword);
page = nextpage;
}
+
+ /* process all the pretty full pages */
+ while (pfpage != NULL) {
+ assert(get_full_page_size((char *)pfpage)->sz == 0);
+ nextpage = pfpage->nextpage;
+ sweep_small_page(getbaseptr(pfpage), pfpage, szword);
+ pfpage = nextpage;
+ }
}
/* process the really full pages, which are the ones which still
diff --git a/c8/stm/smallmalloc.h b/c8/stm/smallmalloc.h
--- a/c8/stm/smallmalloc.h
+++ b/c8/stm/smallmalloc.h
@@ -38,6 +38,11 @@
#define free_uniform_pages (small_page_lists[0])
+/* here are pages that should be in small_page_lists, but since they
+ are "pretty full", let's use them again only after they are less
+ full (XXX: or if we run out of pages). */
+static struct small_free_loc_s *pretty_full_pages[GC_N_SMALL_REQUESTS];
+
/* For is_small_uniform(). */
static uintptr_t first_small_uniform_loc = (uintptr_t) -1;
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