[pypy-commit] stmgc default: Use shadowstack markers to avoid re-scanning the complete stack at every
arigo
noreply at buildbot.pypy.org
Tue Apr 15 18:47:35 CEST 2014
Author: Armin Rigo <arigo at tunes.org>
Branch:
Changeset: r1159:918b1901b1f9
Date: 2014-04-15 18:47 +0200
http://bitbucket.org/pypy/stmgc/changeset/918b1901b1f9/
Log: Use shadowstack markers to avoid re-scanning the complete stack at
every minor collection. Needs to be supported explicitly by pypy.
diff --git a/c7/demo/demo2.c b/c7/demo/demo2.c
--- a/c7/demo/demo2.c
+++ b/c7/demo/demo2.c
@@ -194,6 +194,7 @@
{
int status;
stm_register_thread_local(&stm_thread_local);
+ char *org = (char *)stm_thread_local.shadowstack;
STM_PUSH_ROOT(stm_thread_local, global_chained_list); /* remains forever in the shadow stack */
@@ -202,7 +203,7 @@
}
STM_POP_ROOT(stm_thread_local, global_chained_list);
- assert(stm_thread_local.shadowstack == stm_thread_local.shadowstack_base);
+ assert(org == (char *)stm_thread_local.shadowstack);
unregister_thread_local();
status = sem_post(&done); assert(status == 0);
diff --git a/c7/demo/demo_simple.c b/c7/demo/demo_simple.c
--- a/c7/demo/demo_simple.c
+++ b/c7/demo/demo_simple.c
@@ -50,6 +50,7 @@
{
int status;
stm_register_thread_local(&stm_thread_local);
+ char *org = (char *)stm_thread_local.shadowstack;
tl_counter = 0;
object_t *tmp;
@@ -65,7 +66,7 @@
i++;
}
- assert(stm_thread_local.shadowstack == stm_thread_local.shadowstack_base);
+ assert(org == (char *)stm_thread_local.shadowstack);
stm_unregister_thread_local(&stm_thread_local);
status = sem_post(&done); assert(status == 0);
diff --git a/c7/stm/gcpage.c b/c7/stm/gcpage.c
--- a/c7/stm/gcpage.c
+++ b/c7/stm/gcpage.c
@@ -379,8 +379,8 @@
struct stm_shadowentry_s *current = tl->shadowstack;
struct stm_shadowentry_s *base = tl->shadowstack_base;
while (current-- != base) {
- assert(current->ss != (object_t *)-1);
- mark_visit_object(current->ss, segment_base);
+ if (((uintptr_t)current->ss) > STM_STACK_MARKER_OLD)
+ mark_visit_object(current->ss, segment_base);
}
mark_visit_object(tl->thread_local_obj, segment_base);
diff --git a/c7/stm/nursery.c b/c7/stm/nursery.c
--- a/c7/stm/nursery.c
+++ b/c7/stm/nursery.c
@@ -156,10 +156,32 @@
stm_thread_local_t *tl = STM_SEGMENT->running_thread;
struct stm_shadowentry_s *current = tl->shadowstack;
struct stm_shadowentry_s *base = tl->shadowstack_base;
- while (current-- != base) {
- assert(current->ss != (object_t *)-1);
- minor_trace_if_young(¤t->ss);
+ while (1) {
+ --current;
+ OPT_ASSERT(current >= base);
+
+ switch ((uintptr_t)current->ss) {
+
+ case 0: /* NULL */
+ continue;
+
+ case STM_STACK_MARKER_NEW:
+ /* the marker was not already seen: mark it as seen,
+ but continue looking more deeply in the shadowstack */
+ current->ss = (object_t *)STM_STACK_MARKER_OLD;
+ continue;
+
+ case STM_STACK_MARKER_OLD:
+ /* the marker was already seen: we can stop the
+ root stack tracing at this point */
+ goto interrupt;
+
+ default:
+ /* the stack entry is a regular pointer */
+ minor_trace_if_young(¤t->ss);
+ }
}
+ interrupt:
minor_trace_if_young(&tl->thread_local_obj);
}
diff --git a/c7/stm/setup.c b/c7/stm/setup.c
--- a/c7/stm/setup.c
+++ b/c7/stm/setup.c
@@ -153,11 +153,13 @@
struct stm_shadowentry_s *s = (struct stm_shadowentry_s *)start;
tl->shadowstack = s;
tl->shadowstack_base = s;
+ STM_PUSH_ROOT(*tl, STM_STACK_MARKER_OLD);
}
static void _done_shadow_stack(stm_thread_local_t *tl)
{
- assert(tl->shadowstack >= tl->shadowstack_base);
+ assert(tl->shadowstack > tl->shadowstack_base);
+ assert(tl->shadowstack_base->ss == (object_t *)STM_STACK_MARKER_OLD);
char *start = (char *)tl->shadowstack_base;
_shadowstack_trap_page(start, PROT_READ | PROT_WRITE);
diff --git a/c7/stm/timing.c b/c7/stm/timing.c
--- a/c7/stm/timing.c
+++ b/c7/stm/timing.c
@@ -70,7 +70,7 @@
s_mutex_lock();
fprintf(stderr, "thread %p:\n", tl);
for (i = 0; i < _STM_TIME_N; i++) {
- fprintf(stderr, " %-24s %9u %.3f s\n",
+ fprintf(stderr, " %-24s %9u %8.3f s\n",
timer_names[i], tl->events[i], (double)tl->timing[i]);
}
s_mutex_unlock();
diff --git a/c7/stmgc.h b/c7/stmgc.h
--- a/c7/stmgc.h
+++ b/c7/stmgc.h
@@ -264,6 +264,8 @@
#define STM_PUSH_ROOT(tl, p) ((tl).shadowstack++->ss = (object_t *)(p))
#define STM_POP_ROOT(tl, p) ((p) = (typeof(p))((--(tl).shadowstack)->ss))
#define STM_POP_ROOT_RET(tl) ((--(tl).shadowstack)->ss)
+#define STM_STACK_MARKER_NEW 1
+#define STM_STACK_MARKER_OLD 2
/* Every thread needs to have a corresponding stm_thread_local_t
diff --git a/c7/test/support.py b/c7/test/support.py
--- a/c7/test/support.py
+++ b/c7/test/support.py
@@ -12,6 +12,8 @@
#define STM_NB_SEGMENTS ...
#define _STM_FAST_ALLOC ...
#define _STM_GCFLAG_WRITE_BARRIER ...
+#define STM_STACK_MARKER_NEW ...
+#define STM_STACK_MARKER_OLD ...
struct stm_shadowentry_s {
object_t *ss;
@@ -504,7 +506,8 @@
def pop_root(self):
tl = self.tls[self.current_thread]
curlength = tl.shadowstack - tl.shadowstack_base
- if curlength == 0:
+ assert curlength >= 1
+ if curlength == 1:
raise EmptyStack
assert 0 < curlength <= SHADOWSTACK_LENGTH
tl.shadowstack -= 1
diff --git a/c7/test/test_gcpage.py b/c7/test/test_gcpage.py
--- a/c7/test/test_gcpage.py
+++ b/c7/test/test_gcpage.py
@@ -228,3 +228,22 @@
self.start_transaction()
assert stm_get_char(self.get_thread_local_obj()) == 'L'
+
+ def test_marker_1(self):
+ self.start_transaction()
+ p1 = stm_allocate(600)
+ stm_set_char(p1, 'o')
+ self.push_root(p1)
+ self.push_root(ffi.cast("object_t *", lib.STM_STACK_MARKER_NEW))
+ p2 = stm_allocate(600)
+ stm_set_char(p2, 't')
+ self.push_root(p2)
+ stm_major_collect()
+ assert lib._stm_total_allocated() == 2 * 616
+ #
+ p2 = self.pop_root()
+ m = self.pop_root()
+ assert m == ffi.cast("object_t *", lib.STM_STACK_MARKER_OLD)
+ p1 = self.pop_root()
+ assert stm_get_char(p1) == 'o'
+ assert stm_get_char(p2) == 't'
diff --git a/c7/test/test_nursery.py b/c7/test/test_nursery.py
--- a/c7/test/test_nursery.py
+++ b/c7/test/test_nursery.py
@@ -197,3 +197,42 @@
self.start_transaction()
assert lib.stm_can_move(old) == 0
+
+ def test_marker_1(self):
+ self.start_transaction()
+ p1 = stm_allocate(600)
+ stm_set_char(p1, 'o')
+ self.push_root(p1)
+ self.push_root(ffi.cast("object_t *", lib.STM_STACK_MARKER_NEW))
+ p2 = stm_allocate(600)
+ stm_set_char(p2, 't')
+ self.push_root(p2)
+ stm_minor_collect()
+ assert lib._stm_total_allocated() == 2 * 616
+ #
+ p2 = self.pop_root()
+ m = self.pop_root()
+ assert m == ffi.cast("object_t *", lib.STM_STACK_MARKER_OLD)
+ p1 = self.pop_root()
+ assert stm_get_char(p1) == 'o'
+ assert stm_get_char(p2) == 't'
+
+ def test_marker_2(self):
+ self.start_transaction()
+ p1 = stm_allocate(600)
+ stm_set_char(p1, 'o')
+ self.push_root(p1)
+ self.push_root(ffi.cast("object_t *", lib.STM_STACK_MARKER_OLD))
+ p2 = stm_allocate(600)
+ stm_set_char(p2, 't')
+ self.push_root(p2)
+ stm_minor_collect()
+ assert lib._stm_total_allocated() == 1 * 616
+ #
+ p2 = self.pop_root()
+ m = self.pop_root()
+ assert m == ffi.cast("object_t *", lib.STM_STACK_MARKER_OLD)
+ assert stm_get_char(p2) == 't'
+ # the 'p1' reference is invalid now, don't try to read it.
+ # we check that it's invalid because _stm_total_allocated()
+ # only records one of the two objects.
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