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 <dplotnikov@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 */
+ 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
+ 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
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:
--
2.17.0
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 <dplotnikov@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
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 <dplotnikov@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
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