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Re: [Qemu-devel] [PATCH v4 3/3] qcow2: add zstd cluster compression
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From: |
Denis Plotnikov |
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Subject: |
Re: [Qemu-devel] [PATCH v4 3/3] qcow2: add zstd cluster compression |
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Date: |
Wed, 4 Sep 2019 06:17:46 +0000 |
Kevin, thanks for commenting. I'll resend the series shortly.
Denis
On 03.09.2019 17:12, Kevin Wolf wrote:
> Am 28.08.2019 um 14:56 hat Denis Plotnikov geschrieben:
>> zstd significantly reduces cluster compression time.
>> It provides better compression performance maintaining
>> the same level of compression ratio in comparison with
>> zlib, which, at the moment, has been 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 <address@hidden>
>> ---
>> block/qcow2-threads.c | 107 +++++++++++++++++++++++++++++++++++++++++
>> block/qcow2.c | 7 +++
>> configure | 34 +++++++++++++
>> docs/interop/qcow2.txt | 20 ++++++++
>> qapi/block-core.json | 3 +-
>> 5 files changed, 170 insertions(+), 1 deletion(-)
>>
>> diff --git a/block/qcow2-threads.c b/block/qcow2-threads.c
>> index 14b5bd76fb..f6643976f4 100644
>> --- a/block/qcow2-threads.c
>> +++ b/block/qcow2-threads.c
>> @@ -28,6 +28,11 @@
>> #define ZLIB_CONST
>> #include <zlib.h>
>>
>> +#ifdef CONFIG_ZSTD
>> +#include <zstd.h>
>> +#include <zstd_errors.h>
>> +#endif
>> +
>> #include "qcow2.h"
>> #include "block/thread-pool.h"
>> #include "crypto.h"
>> @@ -165,6 +170,98 @@ static ssize_t qcow2_zlib_decompress(void *dest, size_t
>> dest_size,
>> return ret;
>> }
>>
>> +#ifdef CONFIG_ZSTD
>> +/*
>> + * qcow2_zstd_compress()
>> + *
>> + * Compress @src_size bytes of data using zstd compression method
>> + *
>> + * @dest - destination buffer, @dest_size bytes
>> + * @src - source buffer, @src_size bytes
>> + *
>> + * Returns: compressed size on success
>> + * -ENOMEM destination buffer is not enough to store compressed
>> data
>> + * -EIO on any other error
>> + */
>> +
>> +static ssize_t qcow2_zstd_compress(void *dest, size_t dest_size,
>> + const void *src, size_t src_size)
>> +{
>> + ssize_t ret;
>> + uint32_t *c_size = dest;
>> + /* steal some bytes to store compressed chunk size */
>> + char *d_buf = ((char *) dest) + sizeof(*c_size);
>> +
>> + /* snaity check that we can store the compressed data length */
> sanity
>
>> + if (dest_size < sizeof(*c_size)) {
>> + return -ENOMEM;
>> + }
>> +
>> + dest_size -= sizeof(*c_size);
>> +
>> + ret = ZSTD_compress(d_buf, dest_size, src, src_size, 5);
>> +
>> + if (ZSTD_isError(ret)) {
>> + if (ZSTD_getErrorCode(ret) == ZSTD_error_dstSize_tooSmall) {
>> + return -ENOMEM;
>> + } else {
>> + return -EIO;
>> + }
>> + }
>> +
>> + /* store the compressed chunk size in the very beginning of the buffer
>> */
>> + *c_size = cpu_to_be32(ret);
>> +
>> + return ret + sizeof(*c_size);
>> +}
>> +
>> +/*
>> + * qcow2_zstd_decompress()
>> + *
>> + * Decompress some data (not more than @src_size bytes) to produce exactly
>> + * @dest_size bytes using zstd compression method
>> + *
>> + * @dest - destination buffer, @dest_size bytes
>> + * @src - source buffer, @src_size bytes
>> + *
>> + * Returns: 0 on success
>> + * -EIO on any error
>> + */
>> +
>> +static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size,
>> + const void *src, size_t src_size)
>> +{
>> + ssize_t ret;
>> + /*
>> + * zstd decompress wants to know the exact length of the data
>> + * for that purpose, on the compression the length is stored in
>> + * the very beginning of the compressed buffer
>> + */
>> + uint32_t s_size;
>> + const char *s_buf = ((const char *) src) + sizeof(s_size);
>> +
>> + /* sanity check that we can read the content length */
>> + if (src_size < sizeof(s_size)) {
>> + return -EIO;
>> + }
>> +
>> + s_size = be32_to_cpu( *(const uint32_t *) src);
>> +
>> + /* sanity check that the buffer is big enough to read the content */
>> + if (src_size - sizeof(s_size) < s_size) {
>> + return -EIO;
>> + }
>> +
>> + ret = ZSTD_decompress(dest, dest_size, s_buf, s_size);
>> +
>> + if (ZSTD_isError(ret)) {
>> + return -EIO;
>> + }
>> +
>> + return 0;
>> +}
>> +#endif
>> +
>> static int qcow2_compress_pool_func(void *opaque)
>> {
>> Qcow2CompressData *data = opaque;
>> @@ -216,6 +313,11 @@ qcow2_co_compress(BlockDriverState *bs, void *dest,
>> size_t dest_size,
>> fn = qcow2_zlib_compress;
>> break;
>>
>> +#ifdef CONFIG_ZSTD
>> + case QCOW2_COMPRESSION_TYPE_ZSTD:
>> + fn = qcow2_zstd_compress;
>> + break;
>> +#endif
>> default:
>> return -ENOTSUP;
>> }
>> @@ -248,6 +350,11 @@ qcow2_co_decompress(BlockDriverState *bs, void *dest,
>> size_t dest_size,
>> fn = qcow2_zlib_decompress;
>> break;
>>
>> +#ifdef CONFIG_ZSTD
>> + case QCOW2_COMPRESSION_TYPE_ZSTD:
>> + fn = qcow2_zstd_decompress;
>> + break;
>> +#endif
>> default:
>> return -ENOTSUP;
>> }
>> diff --git a/block/qcow2.c b/block/qcow2.c
>> index 2884b9d9f2..06f346e8cc 100644
>> --- a/block/qcow2.c
>> +++ b/block/qcow2.c
>> @@ -1201,6 +1201,9 @@ static int check_compression_type(BDRVQcow2State *s,
>> Error **errp)
>> {
>> switch (s->compression_type) {
>> case QCOW2_COMPRESSION_TYPE_ZLIB:
>> +#ifdef CONFIG_ZSTD
>> + case QCOW2_COMPRESSION_TYPE_ZSTD:
>> +#endif
>> break;
>>
>> default:
>> @@ -3293,6 +3296,10 @@ qcow2_co_create(BlockdevCreateOptions
>> *create_options, Error **errp)
>> qcow2_opts->compression_type != QCOW2_COMPRESSION_TYPE_ZLIB) {
>>
>> switch (qcow2_opts->compression_type) {
>> +#ifdef CONFIG_ZSTD
>> + case QCOW2_COMPRESSION_TYPE_ZSTD:
>> + break;
>> +#endif
>> default:
>> error_setg_errno(errp, -EINVAL, "Unknown compression type");
>> goto out;
>> diff --git a/configure b/configure
>> index 714e7fb6a1..111c34878d 100755
>> --- a/configure
>> +++ b/configure
>> @@ -441,6 +441,7 @@ opengl_dmabuf="no"
>> cpuid_h="no"
>> avx2_opt=""
>> zlib="yes"
>> +zstd=""
>> capstone=""
>> lzo=""
>> snappy=""
>> @@ -1358,6 +1359,10 @@ for opt do
>> ;;
>> --disable-lzfse) lzfse="no"
>> ;;
>> + --enable-zstd) zstd="yes"
>> + ;;
>> + --disable-zstd) zstd="no"
>> + ;;
>> --enable-guest-agent) guest_agent="yes"
>> ;;
>> --disable-guest-agent) guest_agent="no"
>> @@ -1812,6 +1817,7 @@ disabled with --disable-FEATURE, default is enabled if
>> available:
>> (for reading bzip2-compressed dmg images)
>> lzfse support of lzfse compression library
>> (for reading lzfse-compressed dmg images)
>> + zstd support of zstd compression library
>> seccomp seccomp support
>> coroutine-pool coroutine freelist (better performance)
>> glusterfs GlusterFS backend
>> @@ -2407,6 +2413,30 @@ EOF
>> fi
>> fi
>>
>> +#########################################
>> +# zstd check
>> +
>> +if test "$zstd" == "yes" ; then
> This requires an explicit --enable-zstd for support to be enabled.
>
> The behaviour should be like with other optional libraries:
>
> --enable-zstd: Enable zstd support, fail configure if the library is
> missing
>
> --diable-zstd: Disable zstd support, the library is not needed
>
> default: If libzstd is available, enable zstd support; otherwise
> disable it and continue building without std support
>
> The default isn't correctly implemented yet.
>
>> + if $pkg_config --exists libzstd; then
>> + zstd_cflags=$($pkg_config --cflags libzstd)
>> + zstd_libs=$($pkg_config --libs libzstd)
>> + QEMU_CFLAGS="$zstd_cflags $QEMU_CFLAGS"
>> + LIBS="$zstd_libs $LIBS"
>> + else
>> + cat > $TMPC << EOF
>> +#include <zstd.h>
>> +int main(void) { ZSTD_versionNumber(); return 0; }
>> +EOF
>> + if compile_prog "" "-lzstd" ; then
>> + LIBS="$LIBS -lzstd"
>> + else
>> + feature_not_found "zstd" "Install libzstd-devel"
>> + fi
>> + fi
>> +else
>> + zstd="no"
>> +fi
>> +
>> ##########################################
>> # libseccomp check
>>
>> @@ -6460,6 +6490,7 @@ echo "lzo support $lzo"
>> echo "snappy support $snappy"
>> echo "bzip2 support $bzip2"
>> echo "lzfse support $lzfse"
>> +echo "zstd support $zstd"
>> echo "NUMA host support $numa"
>> echo "libxml2 $libxml2"
>> echo "tcmalloc support $tcmalloc"
>> @@ -7306,6 +7337,9 @@ fi
>> if test "$sheepdog" = "yes" ; then
>> echo "CONFIG_SHEEPDOG=y" >> $config_host_mak
>> fi
>> +if test "$zstd" = "yes" ; then
>> + echo "CONFIG_ZSTD=y" >> $config_host_mak
>> +fi
>>
>> if test "$tcg_interpreter" = "yes"; then
>> QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/tci $QEMU_INCLUDES"
>> diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt
>> index e1be8bd5c3..4b0dc124f5 100644
>> --- a/docs/interop/qcow2.txt
>> +++ b/docs/interop/qcow2.txt
>> @@ -181,6 +181,7 @@ in the description of a field.
>> must be set.
>> Available compression type values:
>> 0: zlib <https://www.zlib.net/> (default)
>> + 1: zstd <http://github.com/facebook/zstd>
>>
>> Directly after the image header, optional sections called header
>> extensions can
>> be stored. Each extension has a structure like the following:
>> @@ -536,6 +537,9 @@ Compressed Clusters Descriptor (x = 62 - (cluster_bits -
>> 8)):
>> Another compressed cluster may map to the tail of the
>> final
>> sector used by this compressed cluster.
>>
>> + The layout of the compressed data depends on the
>> compression
>> + type used for the image (see compressed cluster layout).
>> +
>> If a cluster is unallocated, read requests shall read the data from the
>> backing
>> file (except if bit 0 in the Standard Cluster Descriptor is set). If there
>> is
>> no backing file or the backing file is smaller than the image, they shall
>> read
>> @@ -788,3 +792,19 @@ In the image file the 'enabled' state is reflected by
>> the 'auto' flag. If this
>> flag is set, the software must consider the bitmap as 'enabled' and start
>> tracking virtual disk changes to this bitmap from the first write to the
>> virtual disk. If this flag is not set then the bitmap is disabled.
>> +
>> +=== Compressed cluster layout ===
>> +
>> +The compressed cluster data may have a different layout depending on the
>> +compression type used for the image, and store specific data for the
>> particular
>> +compression type.
>> +
>> +Compressed data layout for the available compression types:
>> +(x = data_space_length - 1)
>> +
>> + zlib <http://zlib.net/>:
>> + Byte 0 - x: the compressed data content
>> + all the space provided used for compressed data
>> + zstd <http://github.com/facebook/zstd>:
>> + Byte 0 - 3: the length of compressed data
>> + 4 - x: the compressed data content
> ...in bytes
>
>> diff --git a/qapi/block-core.json b/qapi/block-core.json
>> index 2c002ca6a9..9e458d5b40 100644
>> --- a/qapi/block-core.json
>> +++ b/qapi/block-core.json
>> @@ -4283,11 +4283,12 @@
>> # Compression type used in qcow2 image file
>> #
>> # @zlib: zlib compression, see <http://zlib.net/>
>> +# @zstd: zstd compression, see <http://github.com/facebook/zstd>
>> #
>> # Since: 4.2
>> ##
>> { 'enum': 'Qcow2CompressionType',
>> - 'data': [ 'zlib' ] }
>> + 'data': [ 'zlib', { 'name': 'zstd', 'if': 'defined(CONFIG_ZSTD)' } ] }
>>
>> ##
>> # @BlockdevCreateOptionsQcow2:
> Kevin