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 <dplotni...@virtuozzo.com> > --- > 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