Re: [PATCH] replay: synchronize on every virtual timer callback

[Pavel Dovgalyuk]

ping


On 06.05.2020 11:17, 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 <address@hidden>
> ---
>   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;
>       }
>       qemu_mutex_unlock(&timer_list->active_timers_lock);
>