[Qemu-devel] [PATCH 0/3] migration: add sztd compression

[Denis Plotnikov]

zstd date compression algorithm shows better performance on data compression.
It might be useful to employ the algorithm in VM migration to reduce CPU usage.
A user will be able to choose between those algorithms, therefor compress-type
migration parameter is added.

Here are some results of performance comparison zstd vs gzip:

host: i7-4790 8xCPU @ 3.60GHz, 16G RAM
migration to the same host
VM: 2xVCPU, 8G RAM total
5G RAM used, memory populated with postgreqsl data
produced by pgbench performance benchmark


Threads: 1 compress – 1 decompress

zstd provides slightly less compression ratio with almost the same
CPU usage but copes with RAM  compression roghly 2 times faster

compression type              zlib       |      zstd
---------------------------------------------------------
compression level          1       5     |   1       5
compression ratio          6.92    7.05  |   6.69    6.89
cpu idle, %                82      83    |   86      80
time, sec                  49      71    |   26      31
time diff to zlib, sec                      -25     -41


Threads: 8 compress – 2 decompress

zstd provides the same migration time with less cpu consumption

compression type         none  |        gzip(zlib)    |          zstd
------------------------------------------------------------------------------
compression level        -     |  1      5       9    |   1       5       15
compression ratio        -     |  6.94   6.99    7.14 |   6.64    6.89    6.93
time, sec                154   |  22     23      27   |   23      23      25
cpu idle, %              99    |  45     30      12   |   70      52      23
cpu idle diff to zlib          |                      |  -25%    -22%    -11%


Denis Plotnikov (3):
  migration: rework compression code for adding more data compressors
  hmp: add compress-type parameter to migration parameters
  migration: add zstd compression

 configure             |  26 ++++
 hmp.c                 |   8 ++
 migration/migration.c |  45 ++++++-
 migration/migration.h |   1 +
 migration/qemu-file.c |  39 ++----
 migration/qemu-file.h |  18 ++-
 migration/ram.c       | 291 ++++++++++++++++++++++++++++++++++--------
 qapi/migration.json   |  26 +++-
 8 files changed, 369 insertions(+), 85 deletions(-)

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2.17.0