On 06/05/20 10:17, Pavel Dovgalyuk wrote: > 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.dovga...@ispras.ru> > --- > util/qemu-timer.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/util/qemu-timer.c b/util/qemu-timer.c > index d548d3c1ad..47833f338f 100644 > --- a/util/qemu-timer.c > +++ b/util/qemu-timer.c > @@ -588,6 +588,11 @@ bool timerlist_run_timers(QEMUTimerList *timer_list) > qemu_mutex_lock(&timer_list->active_timers_lock); > > progress = true; > + /* > + * Callback may insert new checkpoints, therefore add new checkpoint > + * for the virtual timers. > + */ > + need_replay_checkpoint = timer_list->clock->type == > QEMU_CLOCK_VIRTUAL;
You need to check replay_mode != REPLAY_MODE_NONE, either here or in the "if (need_replay_checkpoint)" above. If you choose the latter, you can remove the other "if (replay_mode != REPLAY_MODE_NONE)". Also, there is a comment that says that checkpointing "must only be done once since the clock value stays the same". Is that actually a "can" rather than a "must"? Should the central replay logic have something like a checkpoint count, that prevents adding back-to-back equal checkpoints? Thanks, Paolo > } > qemu_mutex_unlock(&timer_list->active_timers_lock); > >
