Re: [Qemu-devel] [PATCH 4/4] block/qcow2: add zlib-fast compression algorithm

[Eric Blake <eblake@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 1283 bytes --]

On 06/27/2017 07:34 AM, Peter Lieven wrote:
> this adds support for optimized zlib settings which almost

Start sentences with a capital.

> tripples the compression speed while maintaining about

s/tripples/triples/

> the same compressed size.
> 
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  block/qcow2-cluster.c |  3 ++-
>  block/qcow2.c         | 11 +++++++++--
>  block/qcow2.h         |  1 +
>  qemu-img.texi         |  1 +
>  4 files changed, 13 insertions(+), 3 deletions(-)
> 

> +++ b/block/qcow2.h
> @@ -173,6 +173,7 @@ typedef struct Qcow2UnknownHeaderExtension {
>  enum {
>      QCOW2_COMPRESSION_ZLIB          = 0xC0318301,
>      QCOW2_COMPRESSION_LZO           = 0xC0318302,
> +    QCOW2_COMPRESSION_ZLIB_FAST     = 0xC0318303,

Back to my comments on 1/4 - we MUST first get the qcow2 specification
right, rather than adding undocumented headers in the code.  And I still
think you only need one variable-length header extension for covering
all possible algorithms, rather than one header per algorithm.  Let's
get the spec right first, before worrying about the code implementing
the spec.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 604 bytes --]