Re: [PATCH v2] replay: notify CPU on event

[Paolo Bonzini <pbonzini@redhat.com>]

On 29/03/21 09:43, Pavel Dovgalyuk wrote:
> This patch enables vCPU notification to wake it up
> when new async event comes in replay mode.
> 
> The motivation of this patch is the following.
> Consider recorded block async event. It is saved into the log
> with one of the checkpoints. This checkpoint may be passed in
> vCPU loop. In replay mode when this async event is read from
> the log, and block thread task is not finished yet, vCPU thread
> goes to sleep. That is why this patch adds waking up the vCPU
> to process this finished event.
> 
> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
> ---
>   replay/replay-events.c |    1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/replay/replay-events.c b/replay/replay-events.c
> index a1c6bb934e..92dc800219 100644
> --- a/replay/replay-events.c
> +++ b/replay/replay-events.c
> @@ -126,6 +126,7 @@ void replay_add_event(ReplayAsyncEventKind event_kind,
>   
>       g_assert(replay_mutex_locked());
>       QTAILQ_INSERT_TAIL(&events_list, event, events);
> +    qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
>   }

I still do not understand why the qemu_clock_notify function is used to 
notify the CPU.  It would be nice to have a description of the call 
chain in a comment or to have a more appropriate API.  I can queue the 
patch since it's deep in replay-events.c and not in common code, but if 
you post a short description here I'll integrate it.

Paolo