On 10/26/20 12:17 PM, Vladimir Sementsov-Ogievskiy wrote:
> Experiments show, that copy_range is not always making things faster.
> So, to make experimentation simpler, let's add a parameter. Some more
> perf parameters will be added soon, so here is a new struct.
>
> For now, add new backup qmp parameter with x- prefix for the following
> reasons:
>
> - We are going to add more performance parameters, some will be
> related to the whole block-copy process, some only to background
> copying in backup (ignored for copy-before-write operations).
> - On the other hand, we are going to use block-copy interface in other
> block jobs, which will need performance options as well.. And it
> should be the same structure or at least somehow related.
>
> So, there are too much unclean things about how the interface and now
> we need the new options mostly for testing. Let's keep them
> experimental for a while.
>
> In do_backup_common() new x-perf parameter handled in a way to
> make further options addition simpler.
>
> We add use-copy-range with default=true, and we'll change the default
> in further patch, after moving backup to use block-copy.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
> ---
> +++ b/qapi/block-core.json
> @@ -1370,6 +1370,19 @@
> { 'struct': 'BlockdevSnapshot',
> 'data': { 'node': 'str', 'overlay': 'str' } }
>
> +##
> +# @BackupPerf:
> +#
> +# Optional parameters for backup. These parameters don't affect
> +# functionality, but may significantly affect performance.
> +#
> +# @use-copy-range: Use copy offloading. Default true.
> +#
> +# Since: 5.2
We've missed 5.2; this will need to be updated to 6.0
> +##
> +{ 'struct': 'BackupPerf',
> + 'data': { '*use-copy-range': 'bool' }}
> +
> ##
> # @BackupCommon:
> #
> @@ -1425,6 +1438,8 @@
> # above node specified by @drive. If this option is not
> given,
> # a node name is autogenerated. (Since: 4.2)
> #
> +# @x-perf: Performance options. (Since 5.2)
and here
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
