On Sun, Jan 14, 2024 at 10:02 PM Shivam Kumar <shivam.kum...@nutanix.com> wrote:
>
>
>
> > On 04-Jan-2024, at 6:14 AM, Hao Xiang <hao.xi...@bytedance.com> wrote:
> >
> > From: Juan Quintela <quint...@redhat.com>
> >
> > We have to enable it by default until we introduce the new code.
> >
> > Signed-off-by: Juan Quintela <quint...@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)
> > +#
> Should the capability name be something like "zero-page-detection" or just
> “zero-page”?
> CC: Fabiano Rosas
I think the same concern was brought up last time Juan sent out the
original patchset. Right now, the zero page detection is done in the
main migration thread and it is always "ON". This change added a
functionality to move the zero page detection from the main thread to
the multifd sender threads. Now "main-zero-page" is turned "OFF" by
default, and zero page checking is done in the multifd sender thread
(much better performance). If user wants to run the zero page
detection in the main thread (keep current behavior), user can change
"main-zero-page" to "ON".
Renaming it to "zero-page-detection" or just “zero-page” can not
differentiate the old behavior and the new behavior.
Here are the options:
1) Keep the current behavior. "main-zero-page" is OFF by default and
zero page detection runs on the multifd thread by default. User can
turn the switch to "ON" if they want old behavior.
2) Make "main-zero-page" switch ON as default. This would keep the
current behavior by default. User can set it to "OFF" for better
performance.
> > # 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:
> > --
> > 2.30.2
> >
> >
> >
>
