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Re: [Qemu-devel] [PATCH 2/3] replay: allow replay stopping and restartin
From: |
Pavel Dovgalyuk |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] replay: allow replay stopping and restarting |
Date: |
Wed, 29 Jun 2016 12:43:21 +0300 |
Ping?
Pavel Dovgalyuk
> -----Original Message-----
> From: Pavel Dovgalyuk [mailto:address@hidden
> Sent: Monday, June 20, 2016 9:27 AM
> To: 'Paolo Bonzini'; 'Pavel Dovgalyuk'
> Cc: address@hidden; address@hidden; address@hidden; address@hidden
> Subject: RE: [PATCH 2/3] replay: allow replay stopping and restarting
>
> > From: Paolo Bonzini [mailto:address@hidden
> > > From: "Pavel Dovgalyuk" <address@hidden>
> > > This patch fixes bug with stopping and restarting replay
> > > through monitor.
> > >
> > > Signed-off-by: Pavel Dovgalyuk <address@hidden>
> > > ---
> > > block/blkreplay.c | 18 +++++++++++++-----
> > > cpus.c | 1 +
> > > include/sysemu/replay.h | 2 ++
> > > replay/replay-internal.h | 2 --
> > > vl.c | 1 +
> > > 5 files changed, 17 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/block/blkreplay.c b/block/blkreplay.c
> > > index 42f1813..438170c 100644
> > > --- a/block/blkreplay.c
> > > +++ b/block/blkreplay.c
> > > @@ -70,6 +70,14 @@ static void blkreplay_bh_cb(void *opaque)
> > > g_free(req);
> > > }
> > >
> > > +static uint64_t blkreplay_next_id(void)
> > > +{
> > > + if (replay_events_enabled()) {
> > > + return request_id++;
> > > + }
> > > + return 0;
> > > +}
> >
> > What happens if 0 is returned?
>
> It could be any value. When replay events are disables,
> it means that either replay is disabled or execution is stopped.
> In first case we won't pass this requests through the replay queue
> and therefore id is useless.
> In stopped mode we have to keep request_id unchanged to make
> record/replay deterministic.
>
> > I think that you want to call
> > replay_disable_events...
> >
> > > bdrv_drain_all();
> >
> > ... after this bdrv_drain_all.
>
> Why? We disable replay events to avoid adding new block requests
> to the queue. How this is related to drain all?
>
> >
> > I was going to suggest using qemu_add_vm_change_state_handler
> > in replay_start (which could have replaced the existing call
> > to replay_enable_events), but that's not possible if you have
> > to do your calls after bdrv_drain_all.
>
> Pavel Dovgalyuk
[Qemu-devel] [PATCH 1/3] target-ppc: exceptions handling in icount mode, Pavel Dovgalyuk, 2016/06/08
[Qemu-devel] [PATCH 3/3] record/replay: add network support, Pavel Dovgalyuk, 2016/06/08