Author: Remi Meier <remi.me...@inf.ethz.ch>
Branch: c8-new-page-handling
Changeset: r1438:b4042a2af79d
Date: 2014-09-30 17:20 +0200
http://bitbucket.org/pypy/stmgc/changeset/b4042a2af79d/
Log: introduce GCFLAG_WB_EXECUTED to check if we already executed the
write barrier in the same transaction. Alternatively, we could
introduce write-locks again or some other mechanism.
diff --git a/c8/stm/core.c b/c8/stm/core.c
--- a/c8/stm/core.c
+++ b/c8/stm/core.c
@@ -10,7 +10,7 @@
*/
static void import_objects(
int from_segnum, /* or -1: from undo->backup,
- or -2: from undo->backup if not
stm_was_read(obj) */
+ or -2: from undo->backup if not
modified */
uintptr_t pagenum, /* or -1: "all accessible" */
struct stm_undo_s *undo,
struct stm_undo_s *end)
@@ -33,8 +33,16 @@
continue;
}
- if (from_segnum == -2 && _stm_was_read(obj))
+ if (from_segnum == -2 && _stm_was_read(obj) && (obj->stm_flags &
GCFLAG_WB_EXECUTED)) {
+ /* called from stm_validate():
+ > if not was_read(), we certainly didn't modify
+ > if not WB_EXECUTED, we may have read from the obj in a
different page but
+ did not modify it (should not occur right now, but future
proof!)
+ only the WB_EXECUTED alone is not enough, since we may have
imported from a
+ segment's private page (which had the flag set) */
+ assert(IMPLY(_stm_was_read(obj), (obj->stm_flags &
GCFLAG_WB_EXECUTED))); /* for now */
continue; /* only copy unmodified */
+ }
dprintf(("import slice seg=%d obj=%p off=%lu sz=%d pg=%lu\n",
from_segnum, obj, SLICE_OFFSET(undo->slice),
@@ -46,6 +54,11 @@
src = undo->backup + SLICE_OFFSET(undo->slice);
dst = REAL_ADDRESS(STM_SEGMENT->segment_base, oslice);
memcpy(dst, src, SLICE_SIZE(undo->slice));
+
+ if (src_segment_base == NULL) {
+ /* backups never should have WB_EXECUTED */
+ assert(!(obj->stm_flags & GCFLAG_WB_EXECUTED));
+ }
}
}
@@ -57,7 +70,8 @@
{
/* looks at all bk copies of objects overlapping page 'pagenum' and
copies the part in 'pagenum' back to the current segment */
- dprintf(("copy_bk_objs_in_page_from(%d, %lu)\n", from_segnum, pagenum));
+ dprintf(("copy_bk_objs_in_page_from(%d, %lu, %d)\n",
+ from_segnum, pagenum, only_if_not_modified));
struct list_s *list = get_priv_segment(from_segnum)->modified_old_objects;
struct stm_undo_s *undo = (struct stm_undo_s *)list->items;
@@ -429,17 +443,13 @@
/* add to read set: */
stm_read(obj);
- /* XXX: add overflow number again? n^2 algorithm ahead... */
- struct list_s *list = STM_PSEGMENT->modified_old_objects;
- int i, c = list_count(list);
- for (i = 0; i < c; i += 3) {
- if (list->items[i] == (uintptr_t)obj) {
- /* already executed WB once in this transaction. do GC
- part again: */
- obj->stm_flags &= ~GCFLAG_WRITE_BARRIER;
- LIST_APPEND(STM_PSEGMENT->objects_pointing_to_nursery, obj);
- return;
- }
+ if (obj->stm_flags & GCFLAG_WB_EXECUTED) {
+ /* already executed WB once in this transaction. do GC
+ part again: */
+ dprintf(("write_slowpath-fast(%p)\n", obj));
+ obj->stm_flags &= ~GCFLAG_WRITE_BARRIER;
+ LIST_APPEND(STM_PSEGMENT->objects_pointing_to_nursery, obj);
+ return;
}
/* create backup copy (this may cause several page faults
@@ -447,6 +457,7 @@
pages around anyway (kind of card marking)): */
struct object_s *bk_obj = malloc(obj_size);
memcpy(bk_obj, realobj, obj_size);
+ assert(!(bk_obj->stm_flags & GCFLAG_WB_EXECUTED));
dprintf(("write_slowpath(%p): sz=%lu, bk=%p\n", obj, obj_size, bk_obj));
retry:
@@ -483,6 +494,7 @@
update the shared page in stm_validate() except if it is the sole
reader of it. But then we don't actually know which revision the
page is at. */
/* XXX this is a temporary solution I suppose */
+ int i;
for (i = 0; i < NB_SEGMENTS; i++) {
if (i == my_segnum)
continue;
@@ -498,12 +510,6 @@
/* all pages are either private or we were the first to write to a shared
page and therefore got it as our private one */
- /* remove the WRITE_BARRIER flag */
- obj->stm_flags &= ~GCFLAG_WRITE_BARRIER;
-
- /* also add it to the GC list for minor collections */
- LIST_APPEND(STM_PSEGMENT->objects_pointing_to_nursery, obj);
-
/* phew, now add the obj to the write-set and register the
backup copy. */
/* XXX: we should not be here at all fiddling with page status
@@ -538,9 +544,15 @@
OPT_ASSERT(remaining_obj_sz == 0);
release_modified_objs_lock(STM_SEGMENT->segment_num);
-
/* done fiddling with protection and privatization */
release_all_privatization_locks();
+
+ /* remove the WRITE_BARRIER flag and add WB_EXECUTED */
+ obj->stm_flags &= ~GCFLAG_WRITE_BARRIER;
+ obj->stm_flags |= GCFLAG_WB_EXECUTED;
+
+ /* also add it to the GC list for minor collections */
+ LIST_APPEND(STM_PSEGMENT->objects_pointing_to_nursery, obj);
}
static void reset_transaction_read_version(void)
@@ -563,6 +575,18 @@
STM_SEGMENT->transaction_read_version = 1;
}
+static void reset_wb_executed_flags(void)
+{
+ struct list_s *list = STM_PSEGMENT->modified_old_objects;
+ struct stm_undo_s *undo = (struct stm_undo_s *)list->items;
+ struct stm_undo_s *end = (struct stm_undo_s *)(list->items + list->count);
+
+ for (; undo < end; undo++) {
+ object_t *obj = undo->object;
+ obj->stm_flags &= ~GCFLAG_WB_EXECUTED;
+ }
+}
+
static void _stm_start_transaction(stm_thread_local_t *tl)
{
@@ -660,6 +684,7 @@
object_t *obj = undo->object;
char *dst = REAL_ADDRESS(segbase, obj);
assert(((struct object_s *)dst)->stm_flags & GCFLAG_WRITE_BARRIER);
+ assert(!(((struct object_s *)dst)->stm_flags & GCFLAG_WB_EXECUTED));
}
#endif
}
@@ -673,6 +698,8 @@
dprintf(("> stm_commit_transaction()\n"));
minor_collection(1);
+ reset_wb_executed_flags();
+
/* minor_collection() above should have set again all WRITE_BARRIER flags.
Check that again here for the objects that are about to be copied into
the commit log. */
@@ -739,7 +766,6 @@
list_clear(list);
release_modified_objs_lock(segment_num);
-
#pragma pop_macro("STM_SEGMENT")
#pragma pop_macro("STM_PSEGMENT")
}
diff --git a/c8/stm/core.h b/c8/stm/core.h
--- a/c8/stm/core.h
+++ b/c8/stm/core.h
@@ -37,9 +37,11 @@
enum /* stm_flags */ {
GCFLAG_WRITE_BARRIER = _STM_GCFLAG_WRITE_BARRIER,
GCFLAG_HAS_SHADOW = 0x02,
+ GCFLAG_WB_EXECUTED = 0x04,
};
+
/************************************************************/
diff --git a/c8/stm/nursery.c b/c8/stm/nursery.c
--- a/c8/stm/nursery.c
+++ b/c8/stm/nursery.c
@@ -164,7 +164,9 @@
struct list_s *lst = STM_PSEGMENT->objects_pointing_to_nursery;
while (!list_is_empty(lst)) {
- object_t *obj = (object_t *)list_pop_item(lst);;
+ object_t *obj = (object_t *)list_pop_item(lst);
+
+ assert(!_is_in_nursery(obj));
_collect_now(obj);
diff --git a/c8/test/test_random.py b/c8/test/test_random.py
--- a/c8/test/test_random.py
+++ b/c8/test/test_random.py
@@ -8,10 +8,12 @@
def __init__(self, test):
self.content = {'self': test}
self.thread_num = 0
+ self.executed = []
def do(self, cmd):
color = ">> \033[%dm" % (31 + (self.thread_num + 5) % 6)
print >> sys.stderr, color + cmd + "\033[0m"
+ self.executed.append(cmd)
exec cmd in globals(), self.content
@@ -579,7 +581,7 @@
op_minor_collect,
#op_major_collect,
]
- for _ in range(500):
+ for _ in range(1000):
# make sure we are in a transaction:
curr_thread = op_switch_thread(ex, global_state, curr_thread)
@@ -616,6 +618,6 @@
test_fun.__name__ = 'test_random_%d' % seed
return test_fun
- for _seed in range(5000, 5200):
+ for _seed in range(5000, 5400):
_fn = _make_fun(_seed)
locals()[_fn.__name__] = _fn
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