Author: Remi Meier <remi.me...@inf.ethz.ch>
Branch: stmgc-c8
Changeset: r75478:1f67666be256
Date: 2015-01-22 10:58 +0100
http://bitbucket.org/pypy/pypy/changeset/1f67666be256/
Log: import stmgc-c8 5cfce5d61c50
diff too long, truncating to 2000 out of 8126 lines
diff --git a/rpython/translator/stm/import_stmgc.py
b/rpython/translator/stm/import_stmgc.py
--- a/rpython/translator/stm/import_stmgc.py
+++ b/rpython/translator/stm/import_stmgc.py
@@ -15,7 +15,7 @@
yield line
def main(stmgc_dir):
- stmgc_dir = py.path.local(stmgc_dir).join('c7')
+ stmgc_dir = py.path.local(stmgc_dir).join('c8')
popen = subprocess.Popen(['hg', 'id', '-i'], cwd=str(stmgc_dir),
stdout=subprocess.PIPE)
rev = popen.stdout.read().strip()
diff --git a/rpython/translator/stm/src_stm/revision
b/rpython/translator/stm/src_stm/revision
--- a/rpython/translator/stm/src_stm/revision
+++ b/rpython/translator/stm/src_stm/revision
@@ -1,1 +1,1 @@
-957947bc7ad9
+5cfce5d61c50
diff --git a/rpython/translator/stm/src_stm/stm/contention.c
b/rpython/translator/stm/src_stm/stm/contention.c
deleted file mode 100644
--- a/rpython/translator/stm/src_stm/stm/contention.c
+++ /dev/null
@@ -1,323 +0,0 @@
-/* Imported by rpython/translator/stm/import_stmgc.py */
-#ifndef _STM_CORE_H_
-# error "must be compiled via stmgc.c"
-#endif
-
-
-/* Here are the possible kinds of contention:
-
- STM_CONTENTION_WRITE_WRITE
-
- A write-write contention occurs when we are running our
- transaction and detect that we are about to write to an object
- that another thread is also writing to. This kind of
- contention must be resolved before continuing. This *must*
- abort one of the two threads: the caller's thread is not at a
- safe-point, so cannot wait!
-
- It is reported as a timing event with the following two markers:
- the current thread (i.e. where the second-in-time write occurs);
- and the other thread (from its 'modified_old_objects_markers',
- where the first-in-time write occurred).
-
- STM_CONTENTION_WRITE_READ
-
- A write-read contention occurs when we are trying to commit: it
- means that an object we wrote to was also read by another
- transaction. Even though it would seem obvious that we should
- just abort the other thread and proceed in our commit, a more
- subtle answer would be in some cases to wait for the other thread
- to commit first. It would commit having read the old value, and
- then we can commit our change to it.
-
- It is reported as a timing event with only one marker: the
- older location of the write that was done by the current thread.
-
- STM_CONTENTION_INEVITABLE
-
- An inevitable contention occurs when we're trying to become
- inevitable but another thread already is. We can never abort the
- other thread in this case, but we still have the choice to abort
- ourselves or pause until the other thread commits.
-
- It is reported with two markers, one for the current thread and
- one for the other thread. Each marker gives the location that
- attempts to make the transaction inevitable.
-*/
-
-
-struct contmgr_s {
- enum stm_event_e kind;
- struct stm_priv_segment_info_s *other_pseg;
- bool abort_other;
- bool try_sleep; // XXX add a way to timeout, but should handle repeated
- // calls to contention_management() to avoid re-sleeping
- // for the whole duration
-};
-
-
-/************************************************************/
-
-
-__attribute__((unused))
-static void cm_always_abort_myself(struct contmgr_s *cm)
-{
- cm->abort_other = false;
-}
-
-__attribute__((unused))
-static void cm_always_abort_other(struct contmgr_s *cm)
-{
- cm->abort_other = true;
-}
-
-__attribute__((unused))
-static void cm_abort_the_younger(struct contmgr_s *cm)
-{
- if (STM_PSEGMENT->start_time >= cm->other_pseg->start_time) {
- /* We started after the other thread. Abort */
- cm->abort_other = false;
- }
- else {
- cm->abort_other = true;
- }
-}
-
-__attribute__((unused))
-static void cm_always_wait_for_other_thread(struct contmgr_s *cm)
-{
- /* we tried this contention management, but it seems to have
- very bad cases: if thread 1 always reads an object in every
- transaction, and thread 2 wants to write this object just
- once, then thread 2 will pause when it tries to commit;
- it will wait until thread 1 committed; but by the time
- thread 2 resumes again, thread 1 has already started the
- next transaction and read the object again.
- */
- cm_abort_the_younger(cm);
- cm->try_sleep = true;
-}
-
-__attribute__((unused))
-static void cm_pause_if_younger(struct contmgr_s *cm)
-{
- if (STM_PSEGMENT->start_time >= cm->other_pseg->start_time) {
- /* We started after the other thread. Pause */
- cm->try_sleep = true;
- cm->abort_other = false;
- }
- else {
- cm->abort_other = true;
- }
-}
-
-
-/************************************************************/
-
-
-static bool contention_management(uint8_t other_segment_num,
- enum stm_event_e kind,
- object_t *obj)
-{
- assert(_has_mutex());
- assert(other_segment_num != STM_SEGMENT->segment_num);
-
- bool others_may_have_run = false;
- if (must_abort())
- abort_with_mutex();
-
- /* Report the contention */
- timing_contention(kind, other_segment_num, obj);
-
- /* Who should abort here: this thread, or the other thread? */
- struct contmgr_s contmgr;
- contmgr.kind = kind;
- contmgr.other_pseg = get_priv_segment(other_segment_num);
- contmgr.abort_other = false;
- contmgr.try_sleep = false;
-
- /* Pick one contention management... could be made dynamically choosable */
-#ifdef STM_TESTS
- cm_abort_the_younger(&contmgr);
-#else
- cm_pause_if_younger(&contmgr);
-#endif
-
- /* Fix the choices that are found incorrect due to TS_INEVITABLE
- or is_abort() */
- if (is_abort(contmgr.other_pseg->pub.nursery_end)) {
- contmgr.abort_other = true;
- contmgr.try_sleep = false;
- }
- else if (STM_PSEGMENT->transaction_state == TS_INEVITABLE) {
- assert(contmgr.other_pseg->transaction_state != TS_INEVITABLE);
- contmgr.abort_other = true;
- contmgr.try_sleep = false;
- }
- else if (contmgr.other_pseg->transaction_state == TS_INEVITABLE) {
- contmgr.abort_other = false;
- }
-
- /* Do one of three things here...
- */
- if (contmgr.try_sleep && kind != STM_CONTENTION_WRITE_WRITE &&
- contmgr.other_pseg->safe_point != SP_WAIT_FOR_C_TRANSACTION_DONE) {
- others_may_have_run = true;
- /* Sleep.
-
- - Not for write-write contentions, because we're not at a
- safe-point.
-
- - To prevent loops of threads waiting for each others, use
- a crude heuristic of never pausing for a thread that is
- itself already paused here.
- */
- contmgr.other_pseg->signal_when_done = true;
-
- /* tell the other to commit ASAP */
- signal_other_to_commit_soon(contmgr.other_pseg);
-
- dprintf(("pausing...\n"));
-
- timing_event(STM_SEGMENT->running_thread, STM_WAIT_CONTENTION);
-
- cond_signal(C_AT_SAFE_POINT);
- STM_PSEGMENT->safe_point = SP_WAIT_FOR_C_TRANSACTION_DONE;
- cond_wait(C_TRANSACTION_DONE);
- STM_PSEGMENT->safe_point = SP_RUNNING;
- dprintf(("pausing done\n"));
-
- timing_event(STM_SEGMENT->running_thread, STM_WAIT_DONE);
-
- if (must_abort())
- abort_with_mutex();
- }
-
- else if (!contmgr.abort_other) {
- /* tell the other to commit ASAP, since it causes aborts */
- signal_other_to_commit_soon(contmgr.other_pseg);
-
- dprintf(("abort in contention: kind %d\n", kind));
- abort_with_mutex();
- }
-
- else {
- /* We have to signal the other thread to abort, and wait until
- it does. */
- contmgr.other_pseg->pub.nursery_end = NSE_SIGABORT;
-
- timing_event(STM_SEGMENT->running_thread,
- STM_ABORTING_OTHER_CONTENTION);
-
- int sp = contmgr.other_pseg->safe_point;
- switch (sp) {
-
- case SP_RUNNING:
- /* The other thread is running now, so as NSE_SIGABORT was
- set in its 'nursery_end', it will soon enter a
- mutex_lock() and thus abort.
-
- In this case, we will wait until it broadcasts "I'm done
- aborting". Important: this is not a safe point of any
- kind! The shadowstack may not be correct here. It
- should not end in a deadlock, because the target thread
- is, in principle, guaranteed to call abort_with_mutex()
- very soon. Just to be on the safe side, make it really
- impossible for the target thread to later enter the same
- cond_wait(C_ABORTED) (and thus wait, possibly for us,
- ending in a deadlock): check again must_abort() first.
- */
- if (must_abort())
- abort_with_mutex();
-
- others_may_have_run = true;
- dprintf(("contention: wait C_ABORTED...\n"));
- cond_wait(C_ABORTED);
- dprintf(("contention: done\n"));
-
- if (must_abort())
- abort_with_mutex();
- break;
-
- /* The other cases are where the other thread is at a
- safe-point. We wake it up by sending the correct signal.
- We don't have to wait here: the other thread will not do
- anything more than abort when it really wakes up later.
- */
- case SP_WAIT_FOR_C_REQUEST_REMOVED:
- cond_broadcast(C_REQUEST_REMOVED);
- break;
-
- case SP_WAIT_FOR_C_AT_SAFE_POINT:
- cond_broadcast(C_AT_SAFE_POINT);
- break;
-
- case SP_WAIT_FOR_C_TRANSACTION_DONE:
- cond_broadcast(C_TRANSACTION_DONE);
- break;
-
-#ifdef STM_TESTS
- case SP_WAIT_FOR_OTHER_THREAD:
- /* for tests: the other thread will abort as soon as
- stm_stop_safe_point() is called */
- break;
-#endif
-
- default:
- stm_fatalerror("unexpected other_pseg->safe_point: %d", sp);
- }
-
- if (is_aborting_now(other_segment_num)) {
- /* The other thread is blocked in a safe-point with NSE_SIGABORT.
- We don't have to wake it up right now, but we know it will
- abort as soon as it wakes up. We can safely force it to
- reset its state now. */
- dprintf(("killing data structures\n"));
- abort_data_structures_from_segment_num(other_segment_num);
- }
- dprintf(("killed other thread\n"));
-
- /* we should commit soon, we caused an abort */
-
//signal_other_to_commit_soon(get_priv_segment(STM_SEGMENT->segment_num));
- if (!STM_PSEGMENT->signalled_to_commit_soon) {
- STM_PSEGMENT->signalled_to_commit_soon = true;
- stmcb_commit_soon();
- }
- }
- return others_may_have_run;
-}
-
-static void write_write_contention_management(uintptr_t lock_idx,
- object_t *obj)
-{
- s_mutex_lock();
-
- uint8_t prev_owner = ((volatile uint8_t *)write_locks)[lock_idx];
- if (prev_owner != 0 && prev_owner != STM_PSEGMENT->write_lock_num) {
-
- uint8_t other_segment_num = prev_owner;
- assert(get_priv_segment(other_segment_num)->write_lock_num ==
- prev_owner);
-
- contention_management(other_segment_num,
- STM_CONTENTION_WRITE_WRITE, obj);
-
- /* now we return into _stm_write_slowpath() and will try again
- to acquire the write lock on our object. */
- }
-
- s_mutex_unlock();
-}
-
-static bool write_read_contention_management(uint8_t other_segment_num,
- object_t *obj)
-{
- return contention_management(other_segment_num,
- STM_CONTENTION_WRITE_READ, obj);
-}
-
-static void inevitable_contention_management(uint8_t other_segment_num)
-{
- contention_management(other_segment_num,
- STM_CONTENTION_INEVITABLE, NULL);
-}
diff --git a/rpython/translator/stm/src_stm/stm/contention.h
b/rpython/translator/stm/src_stm/stm/contention.h
deleted file mode 100644
--- a/rpython/translator/stm/src_stm/stm/contention.h
+++ /dev/null
@@ -1,17 +0,0 @@
-/* Imported by rpython/translator/stm/import_stmgc.py */
-
-static void write_write_contention_management(uintptr_t lock_idx,
- object_t *obj);
-static bool write_read_contention_management(uint8_t other_segment_num,
- object_t *obj);
-static void inevitable_contention_management(uint8_t other_segment_num);
-
-static inline bool is_abort(uintptr_t nursery_end) {
- return (nursery_end <= _STM_NSE_SIGNAL_MAX && nursery_end != NSE_SIGPAUSE
- && nursery_end != NSE_SIGCOMMITSOON);
-}
-
-static inline bool is_aborting_now(uint8_t other_segment_num) {
- return (is_abort(get_segment(other_segment_num)->nursery_end) &&
- get_priv_segment(other_segment_num)->safe_point != SP_RUNNING);
-}
diff --git a/rpython/translator/stm/src_stm/stm/core.c
b/rpython/translator/stm/src_stm/stm/core.c
--- a/rpython/translator/stm/src_stm/stm/core.c
+++ b/rpython/translator/stm/src_stm/stm/core.c
@@ -4,305 +4,628 @@
#endif
-static void teardown_core(void)
+/* General helper: copies objects into our own segment, from some
+ source described by a range of 'struct stm_undo_s'. Maybe later
+ we could specialize this function to avoid the checks in the
+ inner loop.
+*/
+static void import_objects(
+ int from_segnum, /* or -1: from undo->backup,
+ 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)
{
- memset(write_locks, 0, sizeof(write_locks));
+ char *src_segment_base = (from_segnum >= 0 ? get_segment_base(from_segnum)
+ : NULL);
+
+ assert(IMPLY(from_segnum >= 0,
get_priv_segment(from_segnum)->modification_lock));
+ assert(STM_PSEGMENT->modification_lock);
+
+ DEBUG_EXPECT_SEGFAULT(false);
+ for (; undo < end; undo++) {
+ object_t *obj = undo->object;
+ stm_char *oslice = ((stm_char *)obj) + SLICE_OFFSET(undo->slice);
+ uintptr_t current_page_num = ((uintptr_t)oslice) / 4096;
+
+ if (pagenum == -1) {
+ if (get_page_status_in(STM_SEGMENT->segment_num,
+ current_page_num) == PAGE_NO_ACCESS)
+ continue;
+ }
+ else {
+ if (current_page_num != pagenum)
+ continue;
+ }
+
+ 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 */
+ }
+
+ /* XXX: if the next assert is always true, we should never get a
segfault
+ in this function at all. So the DEBUG_EXPECT_SEGFAULT is correct. */
+ assert((get_page_status_in(STM_SEGMENT->segment_num,
+ current_page_num) != PAGE_NO_ACCESS));
+
+ dprintf(("import slice seg=%d obj=%p off=%lu sz=%d pg=%lu\n",
+ from_segnum, obj, SLICE_OFFSET(undo->slice),
+ SLICE_SIZE(undo->slice), current_page_num));
+ char *src, *dst;
+ if (src_segment_base != NULL)
+ src = REAL_ADDRESS(src_segment_base, oslice);
+ else
+ src = undo->backup;
+ dst = REAL_ADDRESS(STM_SEGMENT->segment_base, oslice);
+ memcpy(dst, src, SLICE_SIZE(undo->slice));
+
+ if (src_segment_base == NULL && SLICE_OFFSET(undo->slice) == 0) {
+ /* check that restored obj doesn't have WB_EXECUTED */
+ assert(!(obj->stm_flags & GCFLAG_WB_EXECUTED));
+ }
+ }
+ DEBUG_EXPECT_SEGFAULT(true);
}
-#ifdef NDEBUG
-#define EVENTUALLY(condition) /* nothing */
-#else
-#define EVENTUALLY(condition) \
- { \
- if (!(condition)) { \
- acquire_privatization_lock(); \
- if (!(condition)) \
- stm_fatalerror("fails: " #condition); \
- release_privatization_lock(); \
- } \
- }
-#endif
-static void check_flag_write_barrier(object_t *obj)
+/* ############# signal handler ############# */
+
+static void copy_bk_objs_in_page_from(int from_segnum, uintptr_t pagenum,
+ bool only_if_not_modified)
{
- /* check that all copies of the object, apart from mine, have the
- GCFLAG_WRITE_BARRIER. (a bit messy because it's possible that we
- read a page in the middle of privatization by another thread)
- */
-#ifndef NDEBUG
- long i;
- struct object_s *o1;
- for (i = 0; i <= NB_SEGMENTS; i++) {
- if (i == STM_SEGMENT->segment_num)
- continue;
- o1 = (struct object_s *)REAL_ADDRESS(get_segment_base(i), obj);
- EVENTUALLY(o1->stm_flags & GCFLAG_WRITE_BARRIER);
- }
-#endif
+ /* 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, %ld, %d)\n",
+ from_segnum, (long)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;
+ struct stm_undo_s *end = (struct stm_undo_s *)(list->items + list->count);
+
+ import_objects(only_if_not_modified ? -2 : -1,
+ pagenum, undo, end);
}
-__attribute__((always_inline))
-static void write_slowpath_overflow_obj(object_t *obj, bool mark_card)
+static void go_to_the_past(uintptr_t pagenum,
+ struct stm_commit_log_entry_s *from,
+ struct stm_commit_log_entry_s *to)
{
- /* An overflow object is an object from the same transaction, but
- outside the nursery. More precisely, it is no longer young,
- i.e. it comes from before the most recent minor collection.
- */
- assert(STM_PSEGMENT->objects_pointing_to_nursery != NULL);
+ assert(STM_PSEGMENT->modification_lock);
+ assert(from->rev_num >= to->rev_num);
+ /* walk BACKWARDS the commit log and update the page 'pagenum',
+ initially at revision 'from', until we reach the revision 'to'. */
- assert(obj->stm_flags & GCFLAG_WRITE_BARRIER);
- if (!mark_card) {
- /* The basic case, with no card marking. We append the object
- into 'objects_pointing_to_nursery', and remove the flag so
- that the write_slowpath will not be called again until the
- next minor collection. */
- if (obj->stm_flags & GCFLAG_CARDS_SET) {
- /* if we clear this flag, we also need to clear the cards */
- _reset_object_cards(get_priv_segment(STM_SEGMENT->segment_num),
- obj, CARD_CLEAR, false);
- }
- obj->stm_flags &= ~(GCFLAG_WRITE_BARRIER | GCFLAG_CARDS_SET);
- LIST_APPEND(STM_PSEGMENT->objects_pointing_to_nursery, obj);
- }
- else {
- /* Card marking. Don't remove GCFLAG_WRITE_BARRIER because we
- need to come back to _stm_write_slowpath_card() for every
- card to mark. Add GCFLAG_CARDS_SET. */
- assert(!(obj->stm_flags & GCFLAG_CARDS_SET));
- obj->stm_flags |= GCFLAG_CARDS_SET;
- assert(STM_PSEGMENT->old_objects_with_cards);
- LIST_APPEND(STM_PSEGMENT->old_objects_with_cards, obj);
+ /* XXXXXXX Recursive algo for now, fix this! */
+ if (from != to) {
+ struct stm_commit_log_entry_s *cl = to->next;
+ go_to_the_past(pagenum, from, cl);
+
+ struct stm_undo_s *undo = cl->written;
+ struct stm_undo_s *end = cl->written + cl->written_count;
+
+ import_objects(-1, pagenum, undo, end);
}
}
-__attribute__((always_inline))
-static void write_slowpath_common(object_t *obj, bool mark_card)
+
+
+static void handle_segfault_in_page(uintptr_t pagenum)
{
- assert(_seems_to_be_running_transaction());
- assert(!_is_young(obj));
- assert(obj->stm_flags & GCFLAG_WRITE_BARRIER);
+ /* assumes page 'pagenum' is ACCESS_NONE, privatizes it,
+ and validates to newest revision */
- uintptr_t base_lock_idx = get_write_lock_idx((uintptr_t)obj);
+ dprintf(("handle_segfault_in_page(%lu), seg %d\n", pagenum,
STM_SEGMENT->segment_num));
- if (IS_OVERFLOW_OBJ(STM_PSEGMENT, obj)) {
- assert(write_locks[base_lock_idx] == 0);
- write_slowpath_overflow_obj(obj, mark_card);
+ /* XXX: bad, but no deadlocks: */
+ acquire_all_privatization_locks();
+
+ long i;
+ int my_segnum = STM_SEGMENT->segment_num;
+
+ assert(get_page_status_in(my_segnum, pagenum) == PAGE_NO_ACCESS);
+
+ /* find who has the most recent revision of our page */
+ int copy_from_segnum = -1;
+ uint64_t most_recent_rev = 0;
+ for (i = 1; i < NB_SEGMENTS; i++) {
+ if (i == my_segnum)
+ continue;
+
+ struct stm_commit_log_entry_s *log_entry;
+ log_entry = get_priv_segment(i)->last_commit_log_entry;
+ if (get_page_status_in(i, pagenum) != PAGE_NO_ACCESS
+ && (copy_from_segnum == -1 || log_entry->rev_num >
most_recent_rev)) {
+ copy_from_segnum = i;
+ most_recent_rev = log_entry->rev_num;
+ }
+ }
+ OPT_ASSERT(copy_from_segnum != my_segnum);
+
+ /* make our page write-ready */
+ page_mark_accessible(my_segnum, pagenum);
+
+ if (copy_from_segnum == -1) {
+ /* this page is only accessible in the sharing segment so far (new
+ allocation). We can thus simply mark it accessible here. */
+ pagecopy(get_virtual_page(my_segnum, pagenum),
+ get_virtual_page(0, pagenum));
+ release_all_privatization_locks();
return;
}
- /* Else, it's an old object and we need to privatise it.
- Do a read-barrier now. Note that this must occur before the
- safepoints that may be issued in write_write_contention_management().
- */
- stm_read(obj);
- /* Take the segment's own lock number */
- uint8_t lock_num = STM_PSEGMENT->write_lock_num;
+ /* before copying anything, acquire modification locks from our and
+ the other segment */
+ uint64_t to_lock = (1UL << copy_from_segnum)| (1UL << my_segnum);
+ acquire_modification_lock_set(to_lock);
+ pagecopy(get_virtual_page(my_segnum, pagenum),
+ get_virtual_page(copy_from_segnum, pagenum));
- /* If CARDS_SET, we entered here at least once already, so we
- already own the write_lock */
- assert(IMPLY(obj->stm_flags & GCFLAG_CARDS_SET,
- write_locks[base_lock_idx] == lock_num));
+ /* if there were modifications in the page, revert them. */
+ copy_bk_objs_in_page_from(copy_from_segnum, pagenum, false);
- /* XXX XXX XXX make the logic of write-locking objects optional! */
+ /* we need to go from 'src_version' to 'target_version'. This
+ might need a walk into the past. */
+ struct stm_commit_log_entry_s *src_version, *target_version;
+ src_version = get_priv_segment(copy_from_segnum)->last_commit_log_entry;
+ target_version = STM_PSEGMENT->last_commit_log_entry;
- /* claim the write-lock for this object. In case we're running the
- same transaction since a long while, the object can be already in
- 'modified_old_objects' (but, because it had GCFLAG_WRITE_BARRIER,
- not in 'objects_pointing_to_nursery'). We'll detect this case
- by finding that we already own the write-lock. */
- retry:
- if (write_locks[base_lock_idx] == 0) {
- /* A lock to prevent reading garbage from
- lookup_other_thread_recorded_marker() */
- acquire_marker_lock(STM_SEGMENT->segment_base);
+ dprintf(("handle_segfault_in_page: rev %lu to rev %lu\n",
+ src_version->rev_num, target_version->rev_num));
+ /* adapt revision of page to our revision:
+ if our rev is higher than the page we copy from, everything
+ is fine as we never read/modified the page anyway
+ */
+ if (src_version->rev_num > target_version->rev_num)
+ go_to_the_past(pagenum, src_version, target_version);
- if (UNLIKELY(!__sync_bool_compare_and_swap(&write_locks[base_lock_idx],
- 0, lock_num))) {
- release_marker_lock(STM_SEGMENT->segment_base);
- goto retry;
+ release_modification_lock_set(to_lock);
+ release_all_privatization_locks();
+}
+
+static void _signal_handler(int sig, siginfo_t *siginfo, void *context)
+{
+ assert(_stm_segfault_expected > 0);
+
+ int saved_errno = errno;
+ char *addr = siginfo->si_addr;
+ dprintf(("si_addr: %p\n", addr));
+ if (addr == NULL || addr < stm_object_pages ||
+ addr >= stm_object_pages+TOTAL_MEMORY) {
+ /* actual segfault, unrelated to stmgc */
+ fprintf(stderr, "Segmentation fault: accessing %p\n", addr);
+ abort();
+ }
+
+ int segnum = get_segment_of_linear_address(addr);
+ if (segnum != STM_SEGMENT->segment_num) {
+ fprintf(stderr, "Segmentation fault: accessing %p (seg %d) from"
+ " seg %d\n", addr, segnum, STM_SEGMENT->segment_num);
+ abort();
+ }
+ dprintf(("-> segment: %d\n", segnum));
+
+ char *seg_base = STM_SEGMENT->segment_base;
+ uintptr_t pagenum = ((char*)addr - seg_base) / 4096UL;
+ if (pagenum < END_NURSERY_PAGE) {
+ fprintf(stderr, "Segmentation fault: accessing %p (seg %d "
+ "page %lu)\n", addr, segnum, pagenum);
+ abort();
+ }
+
+ DEBUG_EXPECT_SEGFAULT(false);
+ handle_segfault_in_page(pagenum);
+ DEBUG_EXPECT_SEGFAULT(true);
+
+ errno = saved_errno;
+ /* now return and retry */
+}
+
+/* ############# commit log ############# */
+
+
+void _dbg_print_commit_log()
+{
+ struct stm_commit_log_entry_s *cl = &commit_log_root;
+
+ fprintf(stderr, "commit log:\n");
+ while ((cl = cl->next)) {
+ if (cl == INEV_RUNNING) {
+ fprintf(stderr, " INEVITABLE\n");
+ return;
+ }
+ fprintf(stderr, " entry at %p: seg %d, rev %lu\n", cl,
cl->segment_num, cl->rev_num);
+ struct stm_undo_s *undo = cl->written;
+ struct stm_undo_s *end = undo + cl->written_count;
+ for (; undo < end; undo++) {
+ fprintf(stderr, " obj %p, size %d, ofs %lu: ", undo->object,
+ SLICE_SIZE(undo->slice), SLICE_OFFSET(undo->slice));
+ /* long i; */
+ /* for (i=0; i<SLICE_SIZE(undo->slice); i += 8) */
+ /* fprintf(stderr, " 0x%016lx", *(long *)(undo->backup + i));
*/
+ fprintf(stderr, "\n");
+ }
+ }
+}
+
+static void reset_modified_from_backup_copies(int segment_num); /* forward */
+
+static bool _stm_validate()
+{
+ /* returns true if we reached a valid state, or false if
+ we need to abort now */
+ dprintf(("_stm_validate()\n"));
+ /* go from last known entry in commit log to the
+ most current one and apply all changes done
+ by other transactions. Abort if we have read one of
+ the committed objs. */
+ struct stm_commit_log_entry_s *first_cl =
STM_PSEGMENT->last_commit_log_entry;
+ struct stm_commit_log_entry_s *next_cl, *last_cl, *cl;
+ int my_segnum = STM_SEGMENT->segment_num;
+ /* Don't check this 'cl'. This entry is already checked */
+
+ if (STM_PSEGMENT->transaction_state == TS_INEVITABLE) {
+ //assert(first_cl->next == INEV_RUNNING);
+ /* the above assert may fail when running a major collection
+ while the commit of the inevitable transaction is in progress */
+ return true;
+ }
+
+ bool needs_abort = false;
+
+ while(1) {
+ /* retry IF: */
+ /* if at the time of "HERE" (s.b.) there happen to be
+ more commits (and bk copies) then it could be that
+ copy_bk_objs_in_page_from (s.b.) reads a bk copy that
+ is itself more recent than last_cl. This is fixed
+ by re-validating. */
+ first_cl = STM_PSEGMENT->last_commit_log_entry;
+ if (first_cl->next == NULL)
+ break;
+
+ if (first_cl->next == INEV_RUNNING) {
+ /* need to reach safe point if an INEV transaction
+ is waiting for us, otherwise deadlock */
+ break;
}
- dprintf_test(("write_slowpath %p -> mod_old\n", obj));
+ /* Find the set of segments we need to copy from and lock them: */
+ uint64_t segments_to_lock = 1UL << my_segnum;
+ cl = first_cl;
+ while ((next_cl = cl->next) != NULL) {
+ if (next_cl == INEV_RUNNING) {
+ /* only validate entries up to INEV */
+ break;
+ }
+ assert(next_cl->rev_num > cl->rev_num);
+ cl = next_cl;
- /* Add the current marker, recording where we wrote to this object */
- timing_record_write();
-
- /* Change to this old object from this transaction.
- Add it to the list 'modified_old_objects'. */
- LIST_APPEND(STM_PSEGMENT->modified_old_objects, obj);
-
- release_marker_lock(STM_SEGMENT->segment_base);
-
- /* We need to privatize the pages containing the object, if they
- are still SHARED_PAGE. The common case is that there is only
- one page in total. */
- uintptr_t first_page = ((uintptr_t)obj) / 4096UL;
-
- /* If the object is in the uniform pages of small objects
- (outside the nursery), then it fits into one page. This is
- the common case. Otherwise, we need to compute it based on
- its location and size. */
- if ((obj->stm_flags & GCFLAG_SMALL_UNIFORM) != 0) {
- page_privatize(first_page);
- }
- else {
- char *realobj;
- size_t obj_size;
- uintptr_t i, end_page;
-
- /* get the size of the object */
- realobj = REAL_ADDRESS(STM_SEGMENT->segment_base, obj);
- obj_size = stmcb_size_rounded_up((struct object_s *)realobj);
-
- /* get the last page containing data from the object */
- end_page = (((uintptr_t)obj) + obj_size - 1) / 4096UL;
-
- for (i = first_page; i <= end_page; i++) {
- page_privatize(i);
+ if (cl->written_count) {
+ segments_to_lock |= (1UL << cl->segment_num);
}
}
+ last_cl = cl;
+
+ /* HERE */
+
+ acquire_privatization_lock(STM_SEGMENT->segment_num);
+ acquire_modification_lock_set(segments_to_lock);
+
+
+ /* import objects from first_cl to last_cl: */
+ if (first_cl != last_cl) {
+ uint64_t segment_really_copied_from = 0UL;
+
+ cl = first_cl;
+ while ((cl = cl->next) != NULL) {
+ if (!needs_abort) {
+ struct stm_undo_s *undo = cl->written;
+ struct stm_undo_s *end = cl->written + cl->written_count;
+ for (; undo < end; undo++) {
+ if (_stm_was_read(undo->object)) {
+ /* first reset all modified objects from the backup
+ copies as soon as the first conflict is
detected;
+ then we will proceed below to update our
segment from
+ the old (but unmodified) version to the newer
version.
+ */
+ reset_modified_from_backup_copies(my_segnum);
+ needs_abort = true;
+
+ dprintf(("_stm_validate() failed for obj %p\n",
undo->object));
+ break;
+ }
+ }
+ }
+
+ if (cl->written_count) {
+ struct stm_undo_s *undo = cl->written;
+ struct stm_undo_s *end = cl->written + cl->written_count;
+
+ segment_really_copied_from |= (1UL << cl->segment_num);
+
+ import_objects(cl->segment_num, -1, undo, end);
+
+ /* here we can actually have our own modified version, so
+ make sure to only copy things that are not modified in
our
+ segment... (if we do not abort) */
+ copy_bk_objs_in_page_from
+ (cl->segment_num, -1, /* any page */
+ !needs_abort); /* if we abort, we still want to copy
everything */
+ }
+
+ /* last fully validated entry */
+ STM_PSEGMENT->last_commit_log_entry = cl;
+ if (cl == last_cl)
+ break;
+ }
+ assert(cl == last_cl);
+
+ /* XXX: this optimization fails in test_basic.py, bug3 */
+ /* OPT_ASSERT(segment_really_copied_from < (1 << NB_SEGMENTS)); */
+ /* int segnum; */
+ /* for (segnum = 1; segnum < NB_SEGMENTS; segnum++) { */
+ /* if (segment_really_copied_from & (1UL << segnum)) { */
+ /* /\* here we can actually have our own modified version,
so */
+ /* make sure to only copy things that are not modified
in our */
+ /* segment... (if we do not abort) *\/ */
+ /* copy_bk_objs_in_page_from( */
+ /* segnum, -1, /\* any page *\/ */
+ /* !needs_abort); /\* if we abort, we still want to
copy everything *\/ */
+ /* } */
+ /* } */
+ }
+
+ /* done with modifications */
+ release_modification_lock_set(segments_to_lock);
+ release_privatization_lock(STM_SEGMENT->segment_num);
}
- else if (write_locks[base_lock_idx] == lock_num) {
-#ifdef STM_TESTS
- bool found = false;
- LIST_FOREACH_R(STM_PSEGMENT->modified_old_objects, object_t *,
- ({ if (item == obj) { found = true; break; } }));
- assert(found);
+
+ return !needs_abort;
+}
+
+static struct stm_commit_log_entry_s *_create_commit_log_entry(void)
+{
+ /* puts all modified_old_objects in a new commit log entry */
+
+ // we don't need the privatization lock, as we are only
+ // reading from modified_old_objs and nobody but us can change it
+ struct list_s *list = STM_PSEGMENT->modified_old_objects;
+ OPT_ASSERT((list_count(list) % 3) == 0);
+ size_t count = list_count(list) / 3;
+ size_t byte_len = sizeof(struct stm_commit_log_entry_s) +
+ count * sizeof(struct stm_undo_s);
+ struct stm_commit_log_entry_s *result = malloc(byte_len);
+
+ result->next = NULL;
+ result->segment_num = STM_SEGMENT->segment_num;
+ result->rev_num = -1; /* invalid */
+ result->written_count = count;
+ memcpy(result->written, list->items, count * sizeof(struct stm_undo_s));
+ return result;
+}
+
+
+static void reset_wb_executed_flags(void);
+static void readd_wb_executed_flags(void);
+static void check_all_write_barrier_flags(char *segbase, struct list_s *list);
+
+static void _validate_and_attach(struct stm_commit_log_entry_s *new)
+{
+ struct stm_commit_log_entry_s *old;
+
+ OPT_ASSERT(new != NULL);
+ /* we are attaching a real CL entry: */
+ bool is_commit = new != INEV_RUNNING;
+
+ while (1) {
+ if (!_stm_validate()) {
+ if (new != INEV_RUNNING)
+ free(new);
+ stm_abort_transaction();
+ }
+
+#if STM_TESTS
+ if (STM_PSEGMENT->transaction_state != TS_INEVITABLE
+ && STM_PSEGMENT->last_commit_log_entry->next == INEV_RUNNING) {
+ /* abort for tests... */
+ stm_abort_transaction();
+ }
#endif
+
+ if (is_commit) {
+ /* we must not remove the WB_EXECUTED flags before validation as
+ it is part of a condition in import_objects() called by
+ copy_bk_objs_in_page_from to not overwrite our modifications.
+ So we do it here: */
+ reset_wb_executed_flags();
+ check_all_write_barrier_flags(STM_SEGMENT->segment_base,
+ STM_PSEGMENT->modified_old_objects);
+ }
+
+ /* try to attach to commit log: */
+ old = STM_PSEGMENT->last_commit_log_entry;
+ if (old->next == NULL) {
+ if (new != INEV_RUNNING) /* INEVITABLE */
+ new->rev_num = old->rev_num + 1;
+
+ if (__sync_bool_compare_and_swap(&old->next, NULL, new))
+ break; /* success! */
+ } else if (old->next == INEV_RUNNING) {
+ /* we failed because there is an INEV transaction running */
+ usleep(10);
+ }
+
+ if (is_commit) {
+ /* XXX: unfortunately, if we failed to attach our CL entry,
+ we have to re-add the WB_EXECUTED flags before we try to
+ validate again because of said condition (s.a) */
+ readd_wb_executed_flags();
+ }
+
+ dprintf(("_validate_and_attach(%p) failed, enter safepoint\n", new));
+
+ /* check for requested safe point. otherwise an INEV transaction
+ may try to commit but cannot because of the busy-loop here. */
+ _stm_collectable_safe_point();
+ }
+}
+
+static void _validate_and_turn_inevitable(void)
+{
+ _validate_and_attach((struct stm_commit_log_entry_s *)INEV_RUNNING);
+}
+
+static void _validate_and_add_to_commit_log(void)
+{
+ struct stm_commit_log_entry_s *old, *new;
+
+ new = _create_commit_log_entry();
+ if (STM_PSEGMENT->transaction_state == TS_INEVITABLE) {
+ old = STM_PSEGMENT->last_commit_log_entry;
+ new->rev_num = old->rev_num + 1;
+ OPT_ASSERT(old->next == INEV_RUNNING);
+
+ /* WB_EXECUTED must be removed before we attach */
+ reset_wb_executed_flags();
+ check_all_write_barrier_flags(STM_SEGMENT->segment_base,
+ STM_PSEGMENT->modified_old_objects);
+
+ bool yes = __sync_bool_compare_and_swap(&old->next, INEV_RUNNING, new);
+ OPT_ASSERT(yes);
}
else {
- /* call the contention manager, and then retry (unless we were
- aborted). */
- write_write_contention_management(base_lock_idx, obj);
- goto retry;
+ _validate_and_attach(new);
}
+ acquire_modification_lock(STM_SEGMENT->segment_num);
+ list_clear(STM_PSEGMENT->modified_old_objects);
+ STM_PSEGMENT->last_commit_log_entry = new;
+ release_modification_lock(STM_SEGMENT->segment_num);
+}
- /* check that we really have a private page */
- assert(is_private_page(STM_SEGMENT->segment_num,
- ((uintptr_t)obj) / 4096));
+/* ############# STM ############# */
+void stm_validate()
+{
+ if (!_stm_validate())
+ stm_abort_transaction();
+}
- /* check that so far all copies of the object have the flag */
- check_flag_write_barrier(obj);
-
- assert(obj->stm_flags & GCFLAG_WRITE_BARRIER);
- if (!mark_card) {
- /* A common case for write_locks[] that was either 0 or lock_num:
- we need to add the object to the appropriate list if there is one.
- */
- if (STM_PSEGMENT->objects_pointing_to_nursery != NULL) {
- dprintf_test(("write_slowpath %p -> old obj_to_nurs\n", obj));
- LIST_APPEND(STM_PSEGMENT->objects_pointing_to_nursery, obj);
- }
-
- if (obj->stm_flags & GCFLAG_CARDS_SET) {
- /* if we clear this flag, we have to tell sync_old_objs that
- everything needs to be synced */
- _reset_object_cards(get_priv_segment(STM_SEGMENT->segment_num),
- obj, CARD_MARKED_OLD, true); /* mark all */
- }
-
- /* remove GCFLAG_WRITE_BARRIER if we succeeded in getting the base
- write-lock (not for card marking). */
- obj->stm_flags &= ~(GCFLAG_WRITE_BARRIER | GCFLAG_CARDS_SET);
- }
- else {
- /* don't remove WRITE_BARRIER, but add CARDS_SET */
- obj->stm_flags |= GCFLAG_CARDS_SET;
- assert(STM_PSEGMENT->old_objects_with_cards);
- LIST_APPEND(STM_PSEGMENT->old_objects_with_cards, obj);
- }
-
- /* for sanity, check again that all other segment copies of this
- object still have the flag (so privatization worked) */
- check_flag_write_barrier(obj);
-}
void _stm_write_slowpath(object_t *obj)
{
- write_slowpath_common(obj, /*mark_card=*/false);
-}
+ assert(_seems_to_be_running_transaction());
+ assert(!_is_in_nursery(obj));
+ assert(obj->stm_flags & GCFLAG_WRITE_BARRIER);
-static bool obj_should_use_cards(object_t *obj)
-{
- struct object_s *realobj = (struct object_s *)
- REAL_ADDRESS(STM_SEGMENT->segment_base, obj);
- long supports = stmcb_obj_supports_cards(realobj);
- if (!supports)
- return 0;
+ int my_segnum = STM_SEGMENT->segment_num;
+ uintptr_t end_page, first_page = ((uintptr_t)obj) / 4096UL;
+ char *realobj;
+ size_t obj_size;
- /* check also if it makes sense: */
- size_t size = stmcb_size_rounded_up(realobj);
- return (size >= _STM_MIN_CARD_OBJ_SIZE);
-}
-
-char _stm_write_slowpath_card_extra(object_t *obj)
-{
- /* the PyPy JIT calls this function directly if it finds that an
- array doesn't have the GCFLAG_CARDS_SET */
- bool mark_card = obj_should_use_cards(obj);
- write_slowpath_common(obj, mark_card);
- return mark_card;
-}
-
-long _stm_write_slowpath_card_extra_base(void)
-{
- /* for the PyPy JIT: _stm_write_slowpath_card_extra_base[obj >> 4]
- is the byte that must be set to CARD_MARKED. The logic below
- does the same, but more explicitly. */
- return (((long)write_locks) - WRITELOCK_START + 1)
- + 0x4000000000000000L; // <- workaround for a clang bug :-(
-}
-
-void _stm_write_slowpath_card(object_t *obj, uintptr_t index)
-{
- /* If CARDS_SET is not set so far, issue a normal write barrier.
- If the object is large enough, ask it to set up the object for
- card marking instead.
- */
- if (!(obj->stm_flags & GCFLAG_CARDS_SET)) {
- char mark_card = _stm_write_slowpath_card_extra(obj);
- if (!mark_card)
- return;
+ realobj = REAL_ADDRESS(STM_SEGMENT->segment_base, obj);
+ obj_size = stmcb_size_rounded_up((struct object_s *)realobj);
+ /* get the last page containing data from the object */
+ if (LIKELY(is_small_uniform(obj))) {
+ end_page = first_page;
+ } else {
+ end_page = (((uintptr_t)obj) + obj_size - 1) / 4096UL;
}
- dprintf_test(("write_slowpath_card %p -> index:%lu\n",
- obj, index));
+ /* add to read set: */
+ stm_read(obj);
- /* We reach this point if we have to mark the card.
- */
- assert(obj->stm_flags & GCFLAG_WRITE_BARRIER);
- assert(obj->stm_flags & GCFLAG_CARDS_SET);
- assert(!(obj->stm_flags & GCFLAG_SMALL_UNIFORM)); /* not supported/tested
*/
+ 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;
+ }
-#ifndef NDEBUG
- struct object_s *realobj = (struct object_s *)
- REAL_ADDRESS(STM_SEGMENT->segment_base, obj);
- size_t size = stmcb_size_rounded_up(realobj);
- /* we need at least one lock in addition to the STM-reserved object
- write-lock */
- assert(size >= 32);
- /* the 'index' must be in range(length-of-obj), but we don't have
- a direct way to know the length. We know that it is smaller
- than the size in bytes. */
- assert(index < size);
-#endif
+ assert(!(obj->stm_flags & GCFLAG_WB_EXECUTED));
+ dprintf(("write_slowpath(%p): sz=%lu\n", obj, obj_size));
- /* Write into the card's lock. This is used by the next minor
- collection to know what parts of the big object may have changed.
- We already own the object here or it is an overflow obj. */
- uintptr_t base_lock_idx = get_write_lock_idx((uintptr_t)obj);
- uintptr_t card_lock_idx = base_lock_idx + get_index_to_card_index(index);
- write_locks[card_lock_idx] = CARD_MARKED;
+ retry:
+ /* privatize pages: */
+ /* XXX don't always acquire all locks... */
+ acquire_all_privatization_locks();
- /* More debug checks */
- dprintf(("mark %p index %lu, card:%lu with %d\n",
- obj, index, get_index_to_card_index(index), CARD_MARKED));
- assert(IMPLY(IS_OVERFLOW_OBJ(STM_PSEGMENT, obj),
- write_locks[base_lock_idx] == 0));
- assert(IMPLY(!IS_OVERFLOW_OBJ(STM_PSEGMENT, obj),
- write_locks[base_lock_idx] == STM_PSEGMENT->write_lock_num));
+ uintptr_t page;
+ for (page = first_page; page <= end_page; page++) {
+ if (get_page_status_in(my_segnum, page) == PAGE_NO_ACCESS) {
+ /* XXX: slow? */
+ release_all_privatization_locks();
+
+ volatile char *dummy = REAL_ADDRESS(STM_SEGMENT->segment_base,
page * 4096UL);
+ *dummy; /* force segfault */
+
+ goto retry;
+ }
+ }
+ /* all pages are private to us and we hold the privatization_locks so
+ we are allowed to modify them */
+
+ /* 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
+ if 'obj' is merely an overflow object. FIX ME, likely by copying
+ the overflow number logic from c7. */
+
+ DEBUG_EXPECT_SEGFAULT(false);
+
+ acquire_modification_lock(STM_SEGMENT->segment_num);
+ uintptr_t slice_sz;
+ uintptr_t in_page_offset = (uintptr_t)obj % 4096UL;
+ uintptr_t remaining_obj_sz = obj_size;
+ for (page = first_page; page <= end_page; page++) {
+ /* XXX Maybe also use mprotect() again to mark pages of the object as
read-only, and
+ only stick it into modified_old_objects page-by-page? Maybe it's
+ possible to do card-marking that way, too. */
+ OPT_ASSERT(remaining_obj_sz);
+
+ slice_sz = remaining_obj_sz;
+ if (in_page_offset + slice_sz > 4096UL) {
+ /* not over page boundaries */
+ slice_sz = 4096UL - in_page_offset;
+ }
+
+ size_t slice_off = obj_size - remaining_obj_sz;
+
+ /* make backup slice: */
+ char *bk_slice = malloc(slice_sz);
+ memcpy(bk_slice, realobj + slice_off, slice_sz);
+
+ STM_PSEGMENT->modified_old_objects = list_append3(
+ STM_PSEGMENT->modified_old_objects,
+ (uintptr_t)obj, /* obj */
+ (uintptr_t)bk_slice, /* bk_addr */
+ NEW_SLICE(slice_off, slice_sz));
+
+ remaining_obj_sz -= slice_sz;
+ in_page_offset = (in_page_offset + slice_sz) % 4096UL; /* mostly 0 */
+ }
+ OPT_ASSERT(remaining_obj_sz == 0);
+
+ /* remove the WRITE_BARRIER flag and add WB_EXECUTED */
+ obj->stm_flags &= ~GCFLAG_WRITE_BARRIER;
+ obj->stm_flags |= GCFLAG_WB_EXECUTED;
+
+ DEBUG_EXPECT_SEGFAULT(true);
+
+ release_modification_lock(STM_SEGMENT->segment_num);
+ /* done fiddling with protection and privatization */
+ release_all_privatization_locks();
+
+ /* 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)
@@ -315,7 +638,7 @@
(long)(NB_READMARKER_PAGES * 4096UL)));
if (mmap(readmarkers, NB_READMARKER_PAGES * 4096UL,
PROT_READ | PROT_WRITE,
- MAP_FIXED | MAP_PAGES_FLAGS, -1, 0) != readmarkers) {
+ MAP_FIXED | MAP_SHARED | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0) !=
readmarkers) {
/* fall-back */
#if STM_TESTS
stm_fatalerror("reset_transaction_read_version: %m");
@@ -325,24 +648,46 @@
STM_SEGMENT->transaction_read_version = 1;
}
-static uint64_t _global_start_time = 0;
+static void reset_wb_executed_flags(void)
+{
+ dprintf(("reset_wb_executed_flags()\n"));
+ 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 readd_wb_executed_flags(void)
+{
+ dprintf(("readd_wb_executed_flags()\n"));
+ 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)
{
assert(!_stm_in_transaction(tl));
- while (!acquire_thread_segment(tl))
- ;
+ while (!acquire_thread_segment(tl)) {}
/* GS invalid before this point! */
assert(STM_PSEGMENT->safe_point == SP_NO_TRANSACTION);
assert(STM_PSEGMENT->transaction_state == TS_NONE);
- timing_event(tl, STM_TRANSACTION_START);
- STM_PSEGMENT->start_time = _global_start_time++;
- STM_PSEGMENT->signalled_to_commit_soon = false;
+ STM_PSEGMENT->transaction_state = TS_REGULAR;
STM_PSEGMENT->safe_point = SP_RUNNING;
- STM_PSEGMENT->marker_inev.object = NULL;
- STM_PSEGMENT->transaction_state = TS_REGULAR;
#ifndef NDEBUG
STM_PSEGMENT->running_pthread = pthread_self();
#endif
@@ -350,16 +695,10 @@
STM_PSEGMENT->threadlocal_at_start_of_transaction = tl->thread_local_obj;
enter_safe_point_if_requested();
- dprintf(("start_transaction\n"));
+ dprintf(("> start_transaction\n"));
- s_mutex_unlock();
+ s_mutex_unlock(); // XXX it's probably possible to not acquire this here
- /* Now running the SP_RUNNING start. We can set our
- 'transaction_read_version' after releasing the mutex,
- because it is only read by a concurrent thread in
- stm_commit_transaction(), which waits until SP_RUNNING
- threads are paused.
- */
uint8_t old_rv = STM_SEGMENT->transaction_read_version;
STM_SEGMENT->transaction_read_version = old_rv + 1;
if (UNLIKELY(old_rv == 0xff)) {
@@ -367,22 +706,17 @@
}
assert(list_is_empty(STM_PSEGMENT->modified_old_objects));
- assert(list_is_empty(STM_PSEGMENT->modified_old_objects_markers));
+ assert(list_is_empty(STM_PSEGMENT->new_objects));
+ assert(list_is_empty(STM_PSEGMENT->objects_pointing_to_nursery));
assert(list_is_empty(STM_PSEGMENT->young_weakrefs));
assert(tree_is_cleared(STM_PSEGMENT->young_outside_nursery));
assert(tree_is_cleared(STM_PSEGMENT->nursery_objects_shadows));
assert(tree_is_cleared(STM_PSEGMENT->callbacks_on_commit_and_abort[0]));
assert(tree_is_cleared(STM_PSEGMENT->callbacks_on_commit_and_abort[1]));
- assert(list_is_empty(STM_PSEGMENT->young_objects_with_light_finalizers));
- assert(STM_PSEGMENT->objects_pointing_to_nursery == NULL);
- assert(STM_PSEGMENT->large_overflow_objects == NULL);
- assert(STM_PSEGMENT->finalizers == NULL);
-#ifndef NDEBUG
- /* this should not be used when objects_pointing_to_nursery == NULL */
- STM_PSEGMENT->modified_old_objects_markers_num_old = 99999999999999999L;
-#endif
check_nursery_at_transaction_start();
+
+ stm_validate();
}
long stm_start_transaction(stm_thread_local_t *tl)
@@ -399,553 +733,142 @@
void stm_start_inevitable_transaction(stm_thread_local_t *tl)
{
- /* used to be more efficient, starting directly an inevitable transaction,
- but there is no real point any more, I believe */
- rewind_jmp_buf rjbuf;
- stm_rewind_jmp_enterframe(tl, &rjbuf);
-
- stm_start_transaction(tl);
- stm_become_inevitable(tl, "start_inevitable_transaction");
-
- stm_rewind_jmp_leaveframe(tl, &rjbuf);
+ s_mutex_lock();
+ _stm_start_transaction(tl);
+ _stm_become_inevitable("stm_start_inevitable_transaction");
}
+#ifdef STM_NO_AUTOMATIC_SETJMP
+void _test_run_abort(stm_thread_local_t *tl) __attribute__((noreturn));
+int stm_is_inevitable(void)
+{
+ switch (STM_PSEGMENT->transaction_state) {
+ case TS_REGULAR: return 0;
+ case TS_INEVITABLE: return 1;
+ default: abort();
+ }
+}
+#endif
/************************************************************/
+static void _finish_transaction()
+{
+ stm_thread_local_t *tl = STM_SEGMENT->running_thread;
-static bool detect_write_read_conflicts(void)
-{
- /* Detect conflicts of the form: we want to commit a write to an object,
- but the same object was also read in a different thread.
- */
- long i;
- for (i = 1; i <= NB_SEGMENTS; i++) {
-
- if (i == STM_SEGMENT->segment_num)
- continue;
-
- if (get_priv_segment(i)->transaction_state == TS_NONE)
- continue; /* no need to check */
-
- if (is_aborting_now(i))
- continue; /* no need to check: is pending immediate abort */
-
- char *remote_base = get_segment_base(i);
- uint8_t remote_version = get_segment(i)->transaction_read_version;
-
- LIST_FOREACH_R(
- STM_PSEGMENT->modified_old_objects,
- object_t * /*item*/,
- ({
- if (was_read_remote(remote_base, item, remote_version)) {
- /* A write-read conflict! */
- dprintf(("write-read conflict on %p, our seg: %d, other:
%ld\n",
- item, STM_SEGMENT->segment_num, i));
- if (write_read_contention_management(i, item)) {
- /* If we reach this point, we didn't abort, but we
- had to wait for the other thread to commit. If we
- did, then we have to restart committing from our
call
- to synchronize_all_threads(). */
- return true;
- }
- /* we aborted the other transaction without waiting, so
- we can just break out of this loop on
- modified_old_objects and continue with the next
- segment */
- break;
- }
- }));
- }
-
- return false;
-}
-
-static void copy_object_to_shared(object_t *obj, int source_segment_num)
-{
- /* Only used by major GC. XXX There is a lot of code duplication
- with synchronize_object_now() but I don't completely see how to
- improve...
- */
- assert(!_is_young(obj));
-
- char *segment_base = get_segment_base(source_segment_num);
- uintptr_t start = (uintptr_t)obj;
- uintptr_t first_page = start / 4096UL;
- struct object_s *realobj = (struct object_s *)
- REAL_ADDRESS(segment_base, obj);
-
- if (realobj->stm_flags & GCFLAG_SMALL_UNIFORM) {
- abort();//XXX WRITE THE FAST CASE
- }
- else {
- ssize_t obj_size = stmcb_size_rounded_up(realobj);
- assert(obj_size >= 16);
- uintptr_t end = start + obj_size;
- uintptr_t last_page = (end - 1) / 4096UL;
-
- for (; first_page <= last_page; first_page++) {
-
- /* Copy the object into the shared page, if needed */
- if (is_private_page(source_segment_num, first_page)) {
-
- uintptr_t copy_size;
- if (first_page == last_page) {
- /* this is the final fragment */
- copy_size = end - start;
- }
- else {
- /* this is a non-final fragment, going up to the
- page's end */
- copy_size = 4096 - (start & 4095);
- }
- /* double-check that the result fits in one page */
- assert(copy_size > 0);
- assert(copy_size + (start & 4095) <= 4096);
-
- char *src = REAL_ADDRESS(segment_base, start);
- char *dst = REAL_ADDRESS(stm_object_pages, start);
- if (copy_size == 4096)
- pagecopy(dst, src);
- else
- memcpy(dst, src, copy_size);
- }
-
- start = (start + 4096) & ~4095;
- }
- }
-}
-
-static void _page_wise_synchronize_object_now(object_t *obj)
-{
- uintptr_t start = (uintptr_t)obj;
- uintptr_t first_page = start / 4096UL;
-
- char *realobj = REAL_ADDRESS(STM_SEGMENT->segment_base, obj);
- ssize_t obj_size = stmcb_size_rounded_up((struct object_s *)realobj);
- assert(obj_size >= 16);
- uintptr_t end = start + obj_size;
- uintptr_t last_page = (end - 1) / 4096UL;
- long i, myself = STM_SEGMENT->segment_num;
-
- for (; first_page <= last_page; first_page++) {
-
- uintptr_t copy_size;
- if (first_page == last_page) {
- /* this is the final fragment */
- copy_size = end - start;
- }
- else {
- /* this is a non-final fragment, going up to the
- page's end */
- copy_size = 4096 - (start & 4095);
- }
- /* double-check that the result fits in one page */
- assert(copy_size > 0);
- assert(copy_size + (start & 4095) <= 4096);
-
- /* First copy the object into the shared page, if needed */
- char *src = REAL_ADDRESS(STM_SEGMENT->segment_base, start);
- char *dst = REAL_ADDRESS(stm_object_pages, start);
- if (is_private_page(myself, first_page)) {
- if (copy_size == 4096)
- pagecopy(dst, src);
- else
- memcpy(dst, src, copy_size);
- }
- else {
- assert(memcmp(dst, src, copy_size) == 0); /* same page */
- }
-
- for (i = 1; i <= NB_SEGMENTS; i++) {
- if (i == myself)
- continue;
-
- /* src = REAL_ADDRESS(stm_object_pages, start); */
- dst = REAL_ADDRESS(get_segment_base(i), start);
- if (is_private_page(i, first_page)) {
- /* The page is a private page. We need to diffuse this
- fragment of object from the shared page to this private
- page. */
- if (copy_size == 4096)
- pagecopy(dst, src);
- else
- memcpy(dst, src, copy_size);
- }
- else {
- assert(!memcmp(dst, src, copy_size)); /* same page */
- }
- }
-
- start = (start + 4096) & ~4095;
- }
-}
-
-static inline bool _has_private_page_in_range(
- long seg_num, uintptr_t start, uintptr_t size)
-{
- uintptr_t first_page = start / 4096UL;
- uintptr_t last_page = (start + size) / 4096UL;
- for (; first_page <= last_page; first_page++)
- if (is_private_page(seg_num, first_page))
- return true;
- return false;
-}
-
-static void _card_wise_synchronize_object_now(object_t *obj)
-{
- assert(obj_should_use_cards(obj));
- assert(!(obj->stm_flags & GCFLAG_CARDS_SET));
- assert(!IS_OVERFLOW_OBJ(STM_PSEGMENT, obj));
-
- uintptr_t offset_itemsize[2];
- struct object_s *realobj = (struct object_s
*)REAL_ADDRESS(STM_SEGMENT->segment_base, obj);
- size_t obj_size = stmcb_size_rounded_up(realobj);
- assert(obj_size >= 32);
- stmcb_get_card_base_itemsize(realobj, offset_itemsize);
- size_t real_idx_count = (obj_size - offset_itemsize[0]) /
offset_itemsize[1];
-
- uintptr_t first_card_index = get_write_lock_idx((uintptr_t)obj);
- uintptr_t card_index = 1;
- uintptr_t last_card_index = get_index_to_card_index(real_idx_count - 1);
/* max valid index */
- long i, myself = STM_SEGMENT->segment_num;
-
- /* simple heuristic to check if probably the whole object is
- marked anyway so we should do page-wise synchronize */
- if (write_locks[first_card_index + 1] == CARD_MARKED_OLD
- && write_locks[first_card_index + last_card_index] == CARD_MARKED_OLD
- && write_locks[first_card_index + (last_card_index >> 1) + 1] ==
CARD_MARKED_OLD) {
-
- dprintf(("card_wise_sync assumes %p,size:%lu is fully marked\n", obj,
obj_size));
- _reset_object_cards(get_priv_segment(STM_SEGMENT->segment_num),
- obj, CARD_CLEAR, false);
- _page_wise_synchronize_object_now(obj);
- return;
- }
-
- dprintf(("card_wise_sync syncs %p,size:%lu card-wise\n", obj, obj_size));
-
- /* Combine multiple marked cards and do a memcpy for them. We don't
- try yet to use page_copy() or otherwise take into account privatization
- of pages (except _has_private_page_in_range) */
- bool all_cards_were_cleared = true;
-
- uintptr_t start_card_index = -1;
- while (card_index <= last_card_index) {
- uintptr_t card_lock_idx = first_card_index + card_index;
- uint8_t card_value = write_locks[card_lock_idx];
-
- if (card_value == CARD_MARKED_OLD) {
- write_locks[card_lock_idx] = CARD_CLEAR;
-
- if (start_card_index == -1) { /* first marked card */
- start_card_index = card_index;
- /* start = (uintptr_t)obj + stmcb_index_to_byte_offset( */
- /* realobj, get_card_index_to_index(card_index)); */
- if (all_cards_were_cleared) {
- all_cards_were_cleared = false;
- }
- }
- }
- else {
- OPT_ASSERT(card_value == CARD_CLEAR);
- }
-
- if (start_card_index != -1 /* something to copy */
- && (card_value != CARD_MARKED_OLD /* found non-marked card
*/
- || card_index == last_card_index)) { /* this is the last card
*/
- /* do the copying: */
- uintptr_t start, copy_size;
- uintptr_t next_card_offset;
- uintptr_t start_card_offset;
- uintptr_t next_card_index = card_index;
-
- if (card_value == CARD_MARKED_OLD) {
- /* card_index is the last card of the object, but we need
- to go one further to get the right offset */
- next_card_index++;
- }
-
- start_card_offset = offset_itemsize[0] +
- get_card_index_to_index(start_card_index) * offset_itemsize[1];
-
- next_card_offset = offset_itemsize[0] +
- get_card_index_to_index(next_card_index) * offset_itemsize[1];
-
- if (next_card_offset > obj_size)
- next_card_offset = obj_size;
-
- start = (uintptr_t)obj + start_card_offset;
- copy_size = next_card_offset - start_card_offset;
- OPT_ASSERT(copy_size > 0);
-
- /* dprintf(("copy %lu bytes\n", copy_size)); */
-
- /* since we have marked cards, at least one page here must be
private */
- assert(_has_private_page_in_range(myself, start, copy_size));
-
- /* copy to shared segment: */
- char *src = REAL_ADDRESS(STM_SEGMENT->segment_base, start);
- char *dst = REAL_ADDRESS(stm_object_pages, start);
- memcpy(dst, src, copy_size);
-
- /* copy to other segments */
- for (i = 1; i <= NB_SEGMENTS; i++) {
- if (i == myself)
- continue;
- if (!_has_private_page_in_range(i, start, copy_size))
- continue;
- /* src = REAL_ADDRESS(stm_object_pages, start); */
- dst = REAL_ADDRESS(get_segment_base(i), start);
- memcpy(dst, src, copy_size);
- }
-
- start_card_index = -1;
- }
-
- card_index++;
- }
-
- if (all_cards_were_cleared) {
- /* well, seems like we never called stm_write_card() on it, so actually
- we need to fall back to synchronize the whole object */
- _page_wise_synchronize_object_now(obj);
- return;
- }
-
-#ifndef NDEBUG
- char *src = REAL_ADDRESS(stm_object_pages, (uintptr_t)obj);
- char *dst;
- for (i = 1; i <= NB_SEGMENTS; i++) {
- dst = REAL_ADDRESS(get_segment_base(i), (uintptr_t)obj);
- assert(memcmp(dst, src, obj_size) == 0);
- }
-#endif
-}
-
-
-static void synchronize_object_now(object_t *obj, bool ignore_cards)
-{
- /* Copy around the version of 'obj' that lives in our own segment.
- It is first copied into the shared pages, and then into other
- segments' own private pages.
-
- Must be called with the privatization lock acquired.
- */
- assert(!_is_young(obj));
- assert(obj->stm_flags & GCFLAG_WRITE_BARRIER);
- assert(STM_PSEGMENT->privatization_lock == 1);
-
- if (obj->stm_flags & GCFLAG_SMALL_UNIFORM) {
- assert(!(obj->stm_flags & GCFLAG_CARDS_SET));
- abort();//XXX WRITE THE FAST CASE
- } else if (ignore_cards || !obj_should_use_cards(obj)) {
- _page_wise_synchronize_object_now(obj);
- } else {
- _card_wise_synchronize_object_now(obj);
- }
-
- _cards_cleared_in_object(get_priv_segment(STM_SEGMENT->segment_num), obj);
-}
-
-static void push_overflow_objects_from_privatized_pages(void)
-{
- if (STM_PSEGMENT->large_overflow_objects == NULL)
- return;
-
- acquire_privatization_lock();
- LIST_FOREACH_R(STM_PSEGMENT->large_overflow_objects, object_t *,
- synchronize_object_now(item, true /*ignore_cards*/));
- release_privatization_lock();
-}
-
-static void push_modified_to_other_segments(void)
-{
- acquire_privatization_lock();
- LIST_FOREACH_R(
- STM_PSEGMENT->modified_old_objects,
- object_t * /*item*/,
- ({
- /* clear the write-lock (note that this runs with all other
- threads paused, so no need to be careful about ordering) */
- uintptr_t lock_idx = (((uintptr_t)item) >> 4) - WRITELOCK_START;
- assert(lock_idx < sizeof(write_locks));
- assert(write_locks[lock_idx] == STM_PSEGMENT->write_lock_num);
- write_locks[lock_idx] = 0;
-
- /* the WRITE_BARRIER flag should have been set again by
- minor_collection() */
- assert((item->stm_flags & GCFLAG_WRITE_BARRIER) != 0);
-
- /* copy the object to the shared page, and to the other
- private pages as needed */
- synchronize_object_now(item, false); /* don't ignore_cards */
- }));
- release_privatization_lock();
-
- list_clear(STM_PSEGMENT->modified_old_objects);
- list_clear(STM_PSEGMENT->modified_old_objects_markers);
-}
-
-static void _finish_transaction(enum stm_event_e event)
-{
STM_PSEGMENT->safe_point = SP_NO_TRANSACTION;
STM_PSEGMENT->transaction_state = TS_NONE;
-
- /* marker_inev is not needed anymore */
- STM_PSEGMENT->marker_inev.object = NULL;
-
- /* reset these lists to NULL for the next transaction */
-
_verify_cards_cleared_in_all_lists(get_priv_segment(STM_SEGMENT->segment_num));
- LIST_FREE(STM_PSEGMENT->objects_pointing_to_nursery);
- list_clear(STM_PSEGMENT->old_objects_with_cards);
- LIST_FREE(STM_PSEGMENT->large_overflow_objects);
-
- stm_thread_local_t *tl = STM_SEGMENT->running_thread;
- timing_event(tl, event);
+ list_clear(STM_PSEGMENT->objects_pointing_to_nursery);
+ list_clear(STM_PSEGMENT->new_objects);
release_thread_segment(tl);
/* cannot access STM_SEGMENT or STM_PSEGMENT from here ! */
}
+static void check_all_write_barrier_flags(char *segbase, struct list_s *list)
+{
+#ifndef NDEBUG
+ 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;
+ struct object_s *dst = (struct object_s*)REAL_ADDRESS(segbase, obj);
+ assert(dst->stm_flags & GCFLAG_WRITE_BARRIER);
+ assert(!(dst->stm_flags & GCFLAG_WB_EXECUTED));
+ }
+#endif
+}
+
+static void push_new_objects_to_other_segments(void)
+{
+ acquire_privatization_lock(STM_SEGMENT->segment_num);
+ LIST_FOREACH_R(STM_PSEGMENT->new_objects, object_t *,
+ ({
+ assert(item->stm_flags & GCFLAG_WB_EXECUTED);
+ item->stm_flags &= ~GCFLAG_WB_EXECUTED;
+ synchronize_object_enqueue(item);
+ }));
+ synchronize_objects_flush();
+ release_privatization_lock(STM_SEGMENT->segment_num);
+
+ /* we can as well clear the list here, since the
+ objects are only useful if the commit succeeds. And
+ we never do a major collection in-between.
+ They should also survive any page privatization happening
+ before the actual commit, since we always do a pagecopy
+ in handle_segfault_in_page() that also copies
+ unknown-to-the-segment/uncommitted things.
+ */
+ list_clear(STM_PSEGMENT->new_objects);
+}
+
+
void stm_commit_transaction(void)
{
- restart_all:
- exec_local_finalizers();
-
assert(!_has_mutex());
assert(STM_PSEGMENT->safe_point == SP_RUNNING);
assert(STM_PSEGMENT->running_pthread == pthread_self());
- minor_collection(/*commit=*/ true);
+ dprintf(("> stm_commit_transaction()\n"));
+ minor_collection(1);
- /* synchronize overflow objects living in privatized pages */
- push_overflow_objects_from_privatized_pages();
-
- s_mutex_lock();
-
- restart:
- /* force all other threads to be paused. They will unpause
- automatically when we are done here, i.e. at mutex_unlock().
- Important: we should not call cond_wait() in the meantime. */
- synchronize_all_threads(STOP_OTHERS_UNTIL_MUTEX_UNLOCK);
-
- if (any_local_finalizers()) {
- s_mutex_unlock();
- goto restart_all;
- }
-
- /* detect conflicts */
- if (detect_write_read_conflicts())
- goto restart;
-
- /* cannot abort any more from here */
- dprintf(("commit_transaction\n"));
-
- assert(STM_SEGMENT->nursery_end == NURSERY_END);
- stm_rewind_jmp_forget(STM_SEGMENT->running_thread);
-
- /* if a major collection is required, do it here */
- if (is_major_collection_requested()) {
- timing_event(STM_SEGMENT->running_thread, STM_GC_MAJOR_START);
- major_collection_now_at_safe_point();
- timing_event(STM_SEGMENT->running_thread, STM_GC_MAJOR_DONE);
- }
-
- /* synchronize modified old objects to other threads */
- push_modified_to_other_segments();
-
_verify_cards_cleared_in_all_lists(get_priv_segment(STM_SEGMENT->segment_num));
-
- commit_finalizers();
-
- /* update 'overflow_number' if needed */
- if (STM_PSEGMENT->overflow_number_has_been_used) {
- highest_overflow_number += GCFLAG_OVERFLOW_NUMBER_bit0;
- assert(highest_overflow_number != /* XXX else, overflow! */
- (uint32_t)-GCFLAG_OVERFLOW_NUMBER_bit0);
- STM_PSEGMENT->overflow_number = highest_overflow_number;
- STM_PSEGMENT->overflow_number_has_been_used = false;
- }
+ push_new_objects_to_other_segments();
+ /* push before validate. otherwise they are reachable too early */
+ _validate_and_add_to_commit_log();
invoke_and_clear_user_callbacks(0); /* for commit */
- /* send what is hopefully the correct signals */
- if (STM_PSEGMENT->transaction_state == TS_INEVITABLE) {
- /* wake up one thread in wait_for_end_of_inevitable_transaction() */
- cond_signal(C_INEVITABLE);
- if (globally_unique_transaction)
- committed_globally_unique_transaction();
+ /* XXX do we still need a s_mutex_lock() section here? */
+ s_mutex_lock();
+ enter_safe_point_if_requested();
+ assert(STM_SEGMENT->nursery_end == NURSERY_END);
+
+ stm_rewind_jmp_forget(STM_SEGMENT->running_thread);
+
+ if (globally_unique_transaction && STM_PSEGMENT->transaction_state ==
TS_INEVITABLE) {
+ committed_globally_unique_transaction();
}
/* done */
- stm_thread_local_t *tl = STM_SEGMENT->running_thread;
- _finish_transaction(STM_TRANSACTION_COMMIT);
+ _finish_transaction();
/* cannot access STM_SEGMENT or STM_PSEGMENT from here ! */
s_mutex_unlock();
-
- invoke_general_finalizers(tl);
}
-void stm_abort_transaction(void)
+static void reset_modified_from_backup_copies(int segment_num)
{
- s_mutex_lock();
- abort_with_mutex();
-}
+#pragma push_macro("STM_PSEGMENT")
+#pragma push_macro("STM_SEGMENT")
+#undef STM_PSEGMENT
+#undef STM_SEGMENT
+ assert(get_priv_segment(segment_num)->modification_lock);
-static void
-reset_modified_from_other_segments(int segment_num)
-{
- /* pull the right versions from segment 0 in order
- to reset our pages as part of an abort.
+ struct stm_priv_segment_info_s *pseg = get_priv_segment(segment_num);
+ struct list_s *list = pseg->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);
- Note that this function is also sometimes called from
- contention.c to clean up the state of a different thread,
- when we would really like it to be aborted now and it is
- suspended at a safe-point.
- */
- struct stm_priv_segment_info_s *pseg = get_priv_segment(segment_num);
- char *local_base = get_segment_base(segment_num);
- char *remote_base = get_segment_base(0);
+ for (; undo < end; undo++) {
+ object_t *obj = undo->object;
+ char *dst = REAL_ADDRESS(pseg->pub.segment_base, obj);
- LIST_FOREACH_R(
- pseg->modified_old_objects,
- object_t * /*item*/,
- ({
- /* memcpy in the opposite direction than
- push_modified_to_other_segments() */
- char *src = REAL_ADDRESS(remote_base, item);
- char *dst = REAL_ADDRESS(local_base, item);
- ssize_t size = stmcb_size_rounded_up((struct object_s *)src);
- memcpy(dst, src, size);
+ memcpy(dst + SLICE_OFFSET(undo->slice),
+ undo->backup,
+ SLICE_SIZE(undo->slice));
- if (obj_should_use_cards(item))
- _reset_object_cards(pseg, item, CARD_CLEAR, false);
+ dprintf(("reset_modified_from_backup_copies(%d): obj=%p off=%lu
bk=%p\n",
+ segment_num, obj, SLICE_OFFSET(undo->slice), undo->backup));
- /* objects in 'modified_old_objects' usually have the
- WRITE_BARRIER flag, unless they have been modified
- recently. Ignore the old flag; after copying from the
- other segment, we should have the flag. */
- assert(((struct object_s *)dst)->stm_flags & GCFLAG_WRITE_BARRIER);
+ free(undo->backup);
+ }
- /* write all changes to the object before we release the
- write lock below. This is needed because we need to
- ensure that if the write lock is not set, another thread
- can get it and then change 'src' in parallel. The
- write_fence() ensures in particular that 'src' has been
- fully read before we release the lock: reading it
- is necessary to write 'dst'. */
- write_fence();
+ /* check that all objects have the GCFLAG_WRITE_BARRIER afterwards */
+ check_all_write_barrier_flags(pseg->pub.segment_base, list);
- /* clear the write-lock */
- uintptr_t lock_idx = (((uintptr_t)item) >> 4) - WRITELOCK_START;
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