From d298ac10add95e2b7f8850332f3b755c8a23d925 Mon Sep 17 00:00:00 2001 From: Denis Plotnikov Date: Thu, 7 May 2020 11:25:20 +0300 Subject: 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 QAPI part: Acked-by: Markus Armbruster Message-Id: <20200507082521.29210-4-dplotnikov@virtuozzo.com> Signed-off-by: Max Reitz --- qapi/block-core.json | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'qapi') diff --git a/qapi/block-core.json b/qapi/block-core.json index 1522e29..6fbacdd 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -4293,11 +4293,12 @@ # Compression type used in qcow2 image file # # @zlib: zlib compression, see +# @zstd: zstd compression, see # # Since: 5.1 ## { 'enum': 'Qcow2CompressionType', - 'data': [ 'zlib' ] } + 'data': [ 'zlib', { 'name': 'zstd', 'if': 'defined(CONFIG_ZSTD)' } ] } ## # @BlockdevCreateOptionsQcow2: -- cgit v1.1