Juan Quintela <[email protected]> writes:
> We have to enable it by default until we introduce the new code.
>
> Signed-off-by: Juan Quintela <[email protected]>
The subject doesn't quite match the patch to the QAPI schema. It claims
"capability to enable/disable zero_page", but ...
> ---
>
> Change it to a capability. As capabilities are off by default, have
> to change MULTIFD_ZERO_PAGE to MAIN_ZERO_PAGE, so it is false for
> default, and true for older versions.
> ---
> qapi/migration.json | 8 +++++++-
> migration/migration.h | 1 +
> hw/core/machine.c | 1 +
> migration/migration.c | 13 ++++++++++++-
> 4 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/qapi/migration.json b/qapi/migration.json
> index 88ecf86ac8..ac5bc071a9 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -472,12 +472,18 @@
> # Requires that QEMU be permitted to use locked memory
> # for guest RAM pages.
> # (since 7.1)
> +#
> # @postcopy-preempt: If enabled, the migration process will allow postcopy
> # requests to preempt precopy stream, so postcopy requests
> # will be handled faster. This is a performance feature
> and
> # should not affect the correctness of postcopy migration.
> # (since 7.1)
> #
> +# @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.
... here, we add a capability to shift certain work to another thread.
No "enable/disable" as far as I can tell. Which one is right?
What's the default?
Not this patch's fault, but needs fixing: we neglect to document the
default for several other parameters.
Wordsmithing nitpick: suggest "done by the thread" or maybe "done in the
thread".
@main-zero-page suggests this is about a special zero page. Perhaps I
can think of a clearer name, but first I need to be sure what the thing
is about.
> +# (since 8.0)
> +#
> # Features:
> # @unstable: Members @x-colo and @x-ignore-shared are experimental.
> #
> @@ -492,7 +498,7 @@
> 'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',
> { 'name': 'x-ignore-shared', 'features': [ 'unstable' ] },
> 'validate-uuid', 'background-snapshot',
> - 'zero-copy-send', 'postcopy-preempt'] }
> + 'zero-copy-send', 'postcopy-preempt', 'main-zero-page'] }
>
> ##
> # @MigrationCapabilityStatus:
