Re: [External] Re: [PATCH v3 01/20] multifd: Add capability to enable/disable zero_page

[Hao Xiang]

On Mon, Jan 8, 2024 at 12:39 PM Fabiano Rosas <farosas@suse.de> wrote:
>
> Hao Xiang <hao.xiang@bytedance.com> writes:
>
> > From: Juan Quintela <quintela@redhat.com>
> >
> > We have to enable it by default until we introduce the new code.
> >
> > Signed-off-by: Juan Quintela <quintela@redhat.com>
> > ---
> >  migration/options.c | 15 +++++++++++++++
> >  migration/options.h |  1 +
> >  qapi/migration.json |  8 +++++++-
> >  3 files changed, 23 insertions(+), 1 deletion(-)
> >
> > diff --git a/migration/options.c b/migration/options.c
> > index 8d8ec73ad9..0f6bd78b9f 100644
> > --- a/migration/options.c
> > +++ b/migration/options.c
> > @@ -204,6 +204,8 @@ Property migration_properties[] = {
> >      DEFINE_PROP_MIG_CAP("x-switchover-ack",
> >                          MIGRATION_CAPABILITY_SWITCHOVER_ACK),
> >      DEFINE_PROP_MIG_CAP("x-dirty-limit", MIGRATION_CAPABILITY_DIRTY_LIMIT),
> > +    DEFINE_PROP_MIG_CAP("main-zero-page",
> > +            MIGRATION_CAPABILITY_MAIN_ZERO_PAGE),
> >      DEFINE_PROP_END_OF_LIST(),
> >  };
> >
> > @@ -284,6 +286,19 @@ bool migrate_multifd(void)
> >      return s->capabilities[MIGRATION_CAPABILITY_MULTIFD];
> >  }
> >
> > +bool migrate_use_main_zero_page(void)
> > +{
> > +    /* MigrationState *s; */
> > +
> > +    /* s = migrate_get_current(); */
> > +
> > +    /*
> > +     * We will enable this when we add the right code.
> > +     * return s->enabled_capabilities[MIGRATION_CAPABILITY_MAIN_ZERO_PAGE];
> > +     */
> > +    return true;
> > +}
> > +
> >  bool migrate_pause_before_switchover(void)
> >  {
> >      MigrationState *s = migrate_get_current();
> > diff --git a/migration/options.h b/migration/options.h
> > index 246c160aee..c901eb57c6 100644
> > --- a/migration/options.h
> > +++ b/migration/options.h
> > @@ -88,6 +88,7 @@ int migrate_multifd_channels(void);
> >  MultiFDCompression migrate_multifd_compression(void);
> >  int migrate_multifd_zlib_level(void);
> >  int migrate_multifd_zstd_level(void);
> > +bool migrate_use_main_zero_page(void);
> >  uint8_t migrate_throttle_trigger_threshold(void);
> >  const char *migrate_tls_authz(void);
> >  const char *migrate_tls_creds(void);
> > diff --git a/qapi/migration.json b/qapi/migration.json
> > index eb2f883513..80c4b13516 100644
> > --- a/qapi/migration.json
> > +++ b/qapi/migration.json
> > @@ -531,6 +531,12 @@
> >  #     and can result in more stable read performance.  Requires KVM
> >  #     with accelerator property "dirty-ring-size" set.  (Since 8.1)
> >  #
> > +#
> > +# @main-zero-page: If enabled, the detection of zero pages will be
> > +#                  done on the main thread.  Otherwise it is done on
> > +#                  the multifd threads.
> > +#                  (since 8.2)
> > +#
> >  # Features:
> >  #
> >  # @deprecated: Member @block is deprecated.  Use blockdev-mirror with
> > @@ -555,7 +561,7 @@
> >             { 'name': 'x-ignore-shared', 'features': [ 'unstable' ] },
> >             'validate-uuid', 'background-snapshot',
> >             'zero-copy-send', 'postcopy-preempt', 'switchover-ack',
> > -           'dirty-limit'] }
> > +           'dirty-limit', 'main-zero-page'] }
> >
> >  ##
> >  # @MigrationCapabilityStatus:
>
> I'll extract this zero page work into a separate series and submit for
> review soon. I want to get people's opinion on it independently of this
> series.

Sounds good. Thanks.