On Wed, Feb 28, 2024 at 1:50 AM Markus Armbruster <arm...@redhat.com> wrote:
>
> Hao Xiang <hao.xi...@bytedance.com> writes:
>
> > 1. Add zero_pages field in MultiFDPacket_t.
> > 2. Implements the zero page detection and handling on the multifd
> > threads for non-compression, zlib and zstd compression backends.
> > 3. Added a new value 'multifd' in ZeroPageDetection enumeration.
> > 4. Handle migration QEMU9.0 -> QEMU8.2 compatibility.
> > 5. Adds zero page counters and updates multifd send/receive tracing
> > format to track the newly added counters.
> >
> > Signed-off-by: Hao Xiang <hao.xi...@bytedance.com>
>
> [...]
>
> > diff --git a/qapi/migration.json b/qapi/migration.json
> > index 1e66272f8f..5a1bb8ad62 100644
> > --- a/qapi/migration.json
> > +++ b/qapi/migration.json
> > @@ -660,10 +660,13 @@
> > #
> > # @legacy: Perform zero page checking from main migration thread.
> > #
> > +# @multifd: Perform zero page checking from multifd sender thread.
> > +#
> > # Since: 9.0
> > +#
> > ##
> > { 'enum': 'ZeroPageDetection',
> > - 'data': [ 'none', 'legacy' ] }
> > + 'data': [ 'none', 'legacy', 'multifd' ] }
> >
> > ##
> > # @BitmapMigrationBitmapAliasTransform:
>
> What happens when you set "zero-page-detection": "multifd" *without*
> enabling multifd migration?
Very good question! Right now the behavior is that if "multifd
migration" is not enabled, it goes through the legacy code path and
the "multifd zero page" option is ignored. The legacy path has its own
zero page checking and will run the same way as before. This is for
backward compatibility.
>
