Re: [Qemu-devel] [PATCH] migration: calculate expected_downtime with ram_bytes_remaining()

[Balamuruhan S]

On 2018-04-10 15:22, Balamuruhan S wrote:
> On Wed, Apr 04, 2018 at 11:04:59AM +0200, Juan Quintela wrote:
> > Balamuruhan S <address@hidden> wrote:
> > > expected_downtime value is not accurate with dirty_pages_rate * page_size,
> > > using ram_bytes_remaining would yeild it correct.
> > >
> > > Signed-off-by: Balamuruhan S <address@hidden>
> >
> > Reviewed-by: Juan Quintela <address@hidden>
> >
> > See my other mail on the thread, my understanding is that your change 
> > is
> > corret (TM).
>
> Juan, Please help to merge it.

Sorry for asking it as during discussion going on, but the reason is 
currently
postcopy migration for HP backed P8 guest from P8 -> P9 is broken and to 
use
precopy with appropriate downtime value we need this patch to be 
backported
to distros that is to be released soon.

> Regards,
> Bala
>
> > Thanks, Juan.
> >
> > > ---
> > >  migration/migration.c | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > >
> > > diff --git a/migration/migration.c b/migration/migration.c
> > > index 58bd382730..4e43dc4f92 100644
> > > --- a/migration/migration.c
> > > +++ b/migration/migration.c
> > > @@ -2245,8 +2245,7 @@ static void migration_update_counters(MigrationState *s,
> > >       * recalculate. 10000 is a small enough number for our purposes
> > >       */
> > >      if (ram_counters.dirty_pages_rate && transferred > 10000) {
> > > -        s->expected_downtime = ram_counters.dirty_pages_rate *
> > > -            qemu_target_page_size() / bandwidth;
> > > +        s->expected_downtime = ram_bytes_remaining() / bandwidth;
> > >      }
> > >
> > >      qemu_file_reset_rate_limit(s->to_dst_file);