Re: [Qemu-devel] [PATCHv2 1/6] block: add accounting for merged requests

[Eric Blake]

On 10/22/2014 07:21 AM, Peter Lieven wrote:
> Signed-off-by: Peter Lieven <address@hidden>
> Reviewed-by: Max Reitz <address@hidden>
> ---
>  block.c                    |    2 ++
>  block/accounting.c         |    7 +++++++
>  block/qapi.c               |    2 ++
>  hmp.c                      |    6 +++++-
>  include/block/accounting.h |    3 +++
>  qapi/block-core.json       |    9 ++++++++-
>  6 files changed, 27 insertions(+), 2 deletions(-)
> 

> +++ b/qapi/block-core.json
> @@ -392,13 +392,20 @@
>  #                     growable sparse files (like qcow2) that are used on top
>  #                     of a physical device.
>  #
> +# @rd_merged: Reserved (Since 2.2)

Does this mean it is always output as 0 for now, but may be non-zero at
some future date if we figure out how to do merged read requests?  Is it
even worth adding the field if it has no semantics?  We can always add
it later when it makes sense, and a client can be smart enough to
realize that a missing field is the same as the field being present with
value 0 (since that is what clients already have to do for 2.1).

I'd feel better with just a bit more documentation or else omitting the
field.  The rest of the patch is okay, though.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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