On 12.09.2019 11:46, Denis Plotnikov wrote:
> ping!
>
> On 05.09.2019 12:31, Denis Plotnikov wrote:
>> v6:
>> * fixed zstd compressed length storing/loading [Eric]
>> * fixed wording, spec section placement [Eric]
>>
>> v5:
>> * type changed for compression_type at BDRVQcow2State [Kevin]
>> * fixed typos, grammar [Kevin]
>> * fixed default config zstd setting [Kevin]
>>
>> v4:
>> * remove not feasible switch case [Vladimir]
>> * add sanity checks to zstd decompresssion [Vladimir]
>> * store zstd compressed length in big endian [Max, Kevin]
>>
>> v3:
>> * relax the compression type setting requirement when
>>     the compression type is not zlib [Eric, Kevin]
>> * add compression type values to the spec [Eric]
>> * fix wording in the spec and descriptions [Eric]
>> * fix functions descriptions [Max]
>> * fix zstd (de)compression functions flaws [Max]
>> * fix zstd related parts of configure file [Max]
>> * rebased to v4.1.0-rc5 and chenged the series version aiming to 4.2
>>
>> v2:
>> * relax the compression type setting restriction in the spec
>> * fix qcow2 header size checking
>> * fix error processing and messaging
>> * fix qcow2 image specific info reporting
>> * set Qcow2CompressionType zstd config dependant
>> * add zstd compressed cluster format description to the spec
>>
>> v1:
>> * extend qcow2 header instead of adding a new incompatible extension header
>> specification re-written accordingly
>> * enable zstd compression via config
>> * fix zstd (de)compression functions
>> * fix comments/description
>> * fix function naming
>>
>> ---
>> The goal of the patch-set is to enable qcow2 to use zstd compression for
>> clusters. ZSTD provides better (de)compression performance than currently
>> used ZLIB. Using it will improve perforamnce (reduce compression time)
>> when the compressed clusters is used, e.g backup scenarios.
>>
>> Also, the patch-set extends qcow2 specification by adding compression_type
>> feature. The feature enables adding ZSTD and another compression algorithms
>> in the future.
>>
>> Here is some measurements ZSTD vs ZLIB:
>>
>> The test:
>> Test compresses and decompresses qemu qcow2 image with just
>> installed rhel-7.6 guest.
>> Image cluster size: 64K. Image on disk size: 2.2G
>>
>> The test was conducted with brd disk to reduce the influence
>> of disk subsystem to the test results.
>> The results is given in seconds.
>>
>> compress cmd:
>> time ./qemu-img convert -O qcow2 -c -o compression_type=[zlib|zstd]
>> src.img [zlib|zstd]_compressed.img
>> decompress cmd
>> time ./qemu-img convert -O qcow2
>> [zlib|zstd]_compressed.img uncompressed.img
>>
>>
>> The results:
>> compression decompression
>> zlib zstd zlib zstd
>> ------------------------------------------------------------
>> real 65.5 16.3 (-75 %) 1.9 1.6 (-16 %)
>> user 65.0 15.8 5.3 2.5
>> sys 3.3 0.2 2.0 2.0
>>
>> Both ZLIB and ZSTD gave the same compression ratio: ~1.5
>> compressed image size in both cases: ~1.4G
>>
>> Denis Plotnikov (3):
>>     qcow2: introduce compression type feature
>>     qcow2: rework the cluster compression routine
>>     qcow2: add zstd cluster compression
>>
>>    block/qcow2-threads.c     | 199 +++++++++++++++++++++++++++++++++++---
>>    block/qcow2.c             |  98 +++++++++++++++++++
>>    block/qcow2.h             |  26 +++--
>>    configure                 |  29 ++++++
>>    docs/interop/qcow2.txt    |  35 ++++++-
>>    include/block/block_int.h |   1 +
>>    qapi/block-core.json      |  23 ++++-
>>    7 files changed, 387 insertions(+), 24 deletions(-)
>>

On 9/18/19 12:29 PM, Denis Plotnikov wrote:
> On 12.09.2019 11:46, Denis Plotnikov wrote:
>> ping!
>>

https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg00943.html

I was under the impression you were addressing feedback from Vladimir.

--js

On 20.09.2019 20:55, John Snow wrote:
>
> On 9/18/19 12:29 PM, Denis Plotnikov wrote:
>> On 12.09.2019 11:46, Denis Plotnikov wrote:
>>> ping!
>>>
> https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg00943.html
>
> I was under the impression you were addressing feedback from Vladimir.
>
> --js

I don't really know what to do with what Vladimir pointed out so I would 
like to get a feedback from Kevin and Eric about this.

Denis