qemu-e2k/docs/interop
Denis Plotnikov d298ac10ad qcow2: add zstd cluster compression
zstd significantly reduces cluster compression time.
It provides better compression performance maintaining
the same level of the compression ratio in comparison with
zlib, which, at the moment, is the only compression
method available.

The performance test results:
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

           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: 1.57
compressed image size in both cases: 1.4G

Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
QAPI part:
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200507082521.29210-4-dplotnikov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-05-13 14:20:31 +02:00
..
bitmaps.rst docs/bitmaps: use QMP lexer instead of json 2019-07-10 15:08:07 -04:00
conf.py docs: Move tools documentation to tools manual 2020-02-25 10:48:06 +00:00
dbus-vmstate.rst Add dbus-vmstate object 2020-01-06 18:41:32 +04:00
dbus.rst Add dbus-vmstate object 2020-01-06 18:41:32 +04:00
firmware.json hw/ppc/prep: Remove the deprecated "prep" machine and the OpenHackware BIOS 2020-02-02 14:07:57 +11:00
index.rst docs: Move tools documentation to tools manual 2020-02-25 10:48:06 +00:00
live-block-operations.rst Remove the deprecated -nodefconfig option 2018-08-31 09:52:46 +02:00
nbd.txt nbd: Prepare for NBD_CMD_FLAG_FAST_ZERO 2019-09-05 16:03:13 -05:00
parallels.txt
pr-helper.rst global: Squash 'the the' 2019-11-06 17:19:40 +01:00
prl-xml.txt docs/interop/prl-xml: description of Parallels Disk format 2018-01-22 14:02:33 +00:00
qcow2.txt qcow2: add zstd cluster compression 2020-05-13 14:20:31 +02:00
qed_spec.txt
qemu-ga-ref.texi
qemu-ga.rst qemu-ga: document vsock-listen in the man page 2020-03-24 11:32:19 -05:00
qemu-qmp-ref.texi
qmp-intro.txt docs/interop/qmp: Improve OOB documentation 2018-07-03 23:09:31 +02:00
qmp-spec.txt docs: Update references to JSON RFC 2018-12-13 19:10:06 +01:00
vhost-user-gpu.rst vhost-user: add vhost_user_gpu_set_socket() 2019-05-29 06:29:07 +02:00
vhost-user.json virtiofsd: add --print-capabilities option 2020-01-23 16:41:36 +00:00
vhost-user.rst misc: Replace zero-length arrays with flexible array member (manual) 2020-03-16 22:07:42 +01:00
vnc-ledstate-Pseudo-encoding.txt