On Wed, Feb 14, 2018 at 06:40:46PM +0000, Dr. David Alan Gilbert wrote:
> * Peter Xu (pet...@redhat.com) wrote:
> > On Tue, Feb 13, 2018 at 06:17:51PM +0000, Dr. David Alan Gilbert wrote:
> > > * Peter Xu (pet...@redhat.com) wrote:
> > > > After we updated the dirty bitmaps of ramblocks, we also need to update
> > > > the critical fields in RAMState to make sure it is ready for a resume.
> > > >
> > > > Signed-off-by: Peter Xu <pet...@redhat.com>
> > > > ---
> > > > migration/ram.c | 40 +++++++++++++++++++++++++++++++++++++++-
> > > > migration/trace-events | 1 +
> > > > 2 files changed, 40 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/migration/ram.c b/migration/ram.c
> > > > index a2a4b05d5c..d275875f54 100644
> > > > --- a/migration/ram.c
> > > > +++ b/migration/ram.c
> > > > @@ -2250,6 +2250,36 @@ static int ram_init_all(RAMState **rsp)
> > > > return 0;
> > > > }
> > > >
> > > > +static void ram_state_resume_prepare(RAMState *rs, QEMUFile *out)
> > > > +{
> > > > + RAMBlock *block;
> > > > + long pages = 0;
> > > > +
> > > > + /*
> > > > + * Postcopy is not using xbzrle/compression, so no need for that.
> > > > + * Also, since source are already halted, we don't need to care
> > > > + * about dirty page logging as well.
> > > > + */
> > > > +
> > > > + RAMBLOCK_FOREACH(block) {
> > > > + pages += bitmap_count_one(block->bmap,
> > > > + block->used_length >>
> > > > TARGET_PAGE_BITS);
> > > > + }
> > > > +
> > > > + /* This may not be aligned with current bitmaps. Recalculate. */
> > > > + rs->migration_dirty_pages = pages;
> > >
> > > migration_dirty_pages is uint64_t - so we should probably do the cast
> > > above and keep 'pages' as uint64_t.
> >
> > Sure.
> >
> > >
> > > > + rs->last_seen_block = NULL;
> > > > + rs->last_sent_block = NULL;
> > > > + rs->last_page = 0;
> > > > + rs->last_version = ram_list.version;
> > >
> > > Do you need to explicitly set
> > > rs->ram_bulk_stage = false;
> > >
> > > if the failure happened just after the start of postcopy and no
> > > requested pages had been sent, I think it might still be set?
> >
> > Could you elaborate what would go wrong even if it's still set?
>
> I think it might start sending all pages rather than just those
> that are dirty/needed; see migration_bitmap_find_dirty.
Ah yes. I should turn it off.
--
Peter Xu
