Kevin Wolf <kw...@redhat.com> writes:
> This information can be useful both for debugging and for management
> tools trying to configure guest devices with the optimal limits
> (possibly across multiple hosts). There is no reason not to make it
> available, so just add it to BlockNodeInfo.
>
> Signed-off-by: Kevin Wolf <kw...@redhat.com>
> ---
> qapi/block-core.json | 59 ++++++++++++++++++++++++++++++++
> block/qapi.c | 34 ++++++++++++++++--
> tests/qemu-iotests/184 | 3 +-
> tests/qemu-iotests/184.out | 8 -----
> tests/qemu-iotests/common.filter | 3 +-
> 5 files changed, 94 insertions(+), 13 deletions(-)
>
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index dc6eb4ae23..eda041ac1c 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -275,6 +275,62 @@
> 'file': 'ImageInfoSpecificFileWrapper'
> } }
>
> +##
> +# @BlockLimitsInfo:
> +#
> +# @request-alignment: Alignment requirement, in bytes, for offset/length of
> I/O
> +# requests.
> +#
> +# @max-discard: Maximum number of bytes that can be discarded at once. If not
> +# present, there is no specific maximum.
> +#
> +# @discard-alignment: Optimal alignment for discard requests in bytes. A
> power
> +# of 2 is best, but not mandatory. If not present, discards don't have a
> +# alignment requirement different from @request-alignment.
What does the second sentence try to convey? As far as I can tell, QMP
has BlockLimitsInfo is only in the result of query-block and
query-named-block-nodes, i.e. it's not something the user picks.
> +#
> +# @max-write-zeroes: Maximum number of bytes that can be zeroed out at once.
> If
> +# not present, there is no specific maximum.
> +#
> +# @write-zeroes-alignment: Optimal alignment for write_zeroes requests in
> +# bytes. A power of 2 is best, but not mandatory. If not present,
> +# write_zeroes doesn't have a alignment requirement different from
> +# @request-alignment.
Likewise.
> +#
> +# @opt-transfer: Optimal transfer length in bytes. If not present, there is
> no
> +# preferred size.
> +#
> +# @max-transfer: Maximal transfer length in bytes. If not present, there is
> no
> +# specific maximum.
> +#
> +# @max-hw-transfer: Maximal hardware transfer length in bytes. Applies
> +# whenever transfers to the device bypass the kernel I/O scheduler, for
> +# example with SG_IO. If not present, there is no specific maximum.
> +#
> +# @max-iov: Maximum number of scatter/gather elements
> +#
> +# @max-hw-iov: Maximal number of scatter/gather elements allowed by the
> hardware.
Maximum number
> +# Applies whenever transfers to the device bypass the kernel I/O
> scheduler,
> +# for example with SG_IO. If not present, the hardware limits is unknown
> +# and @max-iov is always used.
> +#
> +# @min-mem-alignment: memory alignment in bytes so that no bounce buffer is
> needed
> +#
> +# @opt-mem-alignment: memory alignment in bytes that is used for bounce
> buffers
Why is this "opt"? I guess it means "optimal".
> +##
> +{ 'struct': 'BlockLimitsInfo',
> + 'data': { 'request-alignment': 'uint32',
> + '*max-discard': 'uint64',
> + '*discard-alignment': 'uint32',
> + '*max-write-zeroes': 'uint64',
> + '*write-zeroes-alignment': 'uint32',
> + '*opt-transfer': 'uint32',
> + '*max-transfer': 'uint32',
> + '*max-hw-transfer': 'uint32',
> + 'max-iov': 'int',
> + '*max-hw-iov': 'int',
> + 'min-mem-alignment': 'size',
> + 'opt-mem-alignment': 'size' } }
> +
> ##
> # @BlockNodeInfo:
> #
> @@ -304,6 +360,8 @@
> #
> # @snapshots: list of VM snapshots
> #
> +# @limits: block limits that are used for I/O on the node (Since 10.2)
> +#
> # @format-specific: structure supplying additional format-specific
> # information (since 1.7)
> #
> @@ -315,6 +373,7 @@
> '*cluster-size': 'int', '*encrypted': 'bool', '*compressed':
> 'bool',
> '*backing-filename': 'str', '*full-backing-filename': 'str',
> '*backing-filename-format': 'str', '*snapshots': ['SnapshotInfo'],
> + '*limits': 'BlockLimitsInfo',
> '*format-specific': 'ImageInfoSpecific' } }
>
> ##
docs/devel/qapi-code-gen.rst:
For legibility, wrap text paragraphs so every line is at most 70
characters long.
Separate sentences with two spaces.
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