* [PATCH v2] replay: synchronize on every virtual timer callback
@ 2020-05-22 6:35 Pavel Dovgalyuk
0 siblings, 0 replies; only message in thread
From: Pavel Dovgalyuk @ 2020-05-22 6:35 UTC (permalink / raw)
To: qemu-devel; +Cc: pbonzini, alex.bennee, pavel.dovgaluk, dovgaluk
Sometimes virtual timer callbacks depend on order
of virtual timer processing and warping of virtual clock.
Therefore every callback should be logged to make replay deterministic.
This patch creates a checkpoint before every virtual timer callback.
With these checkpoints virtual timers processing and clock warping
events order is completely deterministic.
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
--
v2:
- remove mutex lock/unlock for virtual clock checkpoint since it is
not process any asynchronous events (commit ca9759c2a92f528f256fef0e3922416f7bb47bf9)
- bump record/replay log file version
---
0 files changed
diff --git a/replay/replay.c b/replay/replay.c
index 706c7b4f4b..53edad1377 100644
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -22,7 +22,7 @@
/* Current version of the replay mechanism.
Increase it when file format changes. */
-#define REPLAY_VERSION 0xe02009
+#define REPLAY_VERSION 0xe0200a
/* Size of replay log header */
#define HEADER_SIZE (sizeof(uint32_t) + sizeof(uint64_t))
diff --git a/util/qemu-timer.c b/util/qemu-timer.c
index b6575a2cd5..f62b4feecd 100644
--- a/util/qemu-timer.c
+++ b/util/qemu-timer.c
@@ -501,7 +501,6 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
bool progress = false;
QEMUTimerCB *cb;
void *opaque;
- bool need_replay_checkpoint = false;
if (!atomic_read(&timer_list->active_timers)) {
return false;
@@ -517,16 +516,6 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
break;
default:
case QEMU_CLOCK_VIRTUAL:
- if (replay_mode != REPLAY_MODE_NONE) {
- /* Checkpoint for virtual clock is redundant in cases where
- * it's being triggered with only non-EXTERNAL timers, because
- * these timers don't change guest state directly.
- * Since it has conditional dependence on specific timers, it is
- * subject to race conditions and requires special handling.
- * See below.
- */
- need_replay_checkpoint = true;
- }
break;
case QEMU_CLOCK_HOST:
if (!replay_checkpoint(CHECKPOINT_CLOCK_HOST)) {
@@ -559,19 +548,16 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
*/
break;
}
- if (need_replay_checkpoint
- && !(ts->attributes & QEMU_TIMER_ATTR_EXTERNAL)) {
- /* once we got here, checkpoint clock only once */
- need_replay_checkpoint = false;
+ /* Checkpoint for virtual clock is redundant in cases where
+ * it's being triggered with only non-EXTERNAL timers, because
+ * these timers don't change guest state directly.
+ */
+ if (replay_mode != REPLAY_MODE_NONE
+ && timer_list->clock->type == QEMU_CLOCK_VIRTUAL
+ && !(ts->attributes & QEMU_TIMER_ATTR_EXTERNAL)
+ && !replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
qemu_mutex_unlock(&timer_list->active_timers_lock);
- if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
- goto out;
- }
- qemu_mutex_lock(&timer_list->active_timers_lock);
- /* The lock was released; start over again in case the list was
- * modified.
- */
- continue;
+ goto out;
}
/* remove timer from the list before calling the callback */
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2020-05-22 6:36 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-22 6:35 [PATCH v2] replay: synchronize on every virtual timer callback Pavel Dovgalyuk
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).