| Message ID | 20200331131743.17448-4-dplotnikov@virtuozzo.com |
|---|---|
| State | New |
| Headers | show |
| Series | None | expand |
31.03.2020 16:17, Denis Plotnikov wrote: > 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 <dplotnikov@virtuozzo.com> > QAPI part: > Acked-by: Markus Armbruster <armbru@redhat.com> > --- Hi! I have three suggestions: 1. return type of qcow2 compression functions is ssize_t, and return type of zstd is size_t. I think better is not to mix them. 2. safe check for ENOMEM in compression part - avoid overflow ( maximum of paranoia :) 3. slightly more tolerate sanity check in decompression part: allow zstd to make progress only on one of the buffers Here is it, and if you like it, take it together with my Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> diff --git a/block/qcow2-threads.c b/block/qcow2-threads.c index 0b04f30bd8..208218c8f3 100644 --- a/block/qcow2-threads.c +++ b/block/qcow2-threads.c @@ -188,7 +188,7 @@ static ssize_t qcow2_zlib_decompress(void *dest, size_t dest_size, static ssize_t qcow2_zstd_compress(void *dest, size_t dest_size, const void *src, size_t src_size) { - size_t ret; + ssize_t ret; ZSTD_outBuffer output = { dest, dest_size, 0 }; ZSTD_inBuffer input = { src, src_size, 0 }; ZSTD_CCtx *cctx; @@ -214,13 +214,14 @@ static ssize_t qcow2_zstd_compress(void *dest, size_t dest_size, * We want to use zstd streamed interface on decompression, * as we won't know the exact size of the compressed data. */ - ret = ZSTD_compressStream2(cctx, &output, &input, ZSTD_e_end); - if (ZSTD_isError(ret)) { + size_t zstd_ret = ZSTD_compressStream2(cctx, &output, &input, + ZSTD_e_end); + if (ZSTD_isError(zstd_ret)) { ret = -EIO; goto out; } /* Dest buffer isn't big enough to store compressed content */ - if (output.pos + ret > output.size) { + if (zstd_ret > output.size - output.pos) { ret = -ENOMEM; goto out; } @@ -248,7 +249,8 @@ out: static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size, const void *src, size_t src_size) { - size_t ret = 0; + ssize_t ret = 0; + size_t zstd_ret = 0; ZSTD_outBuffer output = { dest, dest_size, 0 }; ZSTD_inBuffer input = { src, src_size, 0 }; ZSTD_DCtx *dctx = ZSTD_createDCtx(); @@ -269,8 +271,9 @@ static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size, * ZSTD_decompressStream reads another ONE full frame. */ while (output.pos < output.size) { - size_t last_input_pos = input.pos; - ret = ZSTD_decompressStream(dctx, &output, &input); + size_t last_progress = input.pos + output.pos; + + zstd_ret = ZSTD_decompressStream(dctx, &output, &input); /* * zstd manual doesn't explicitly states what happens, * if the read the frame partially. But, based on the @@ -278,7 +281,7 @@ static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size, * and have read all the frames from the input, * we end up with error here. */ - if (ZSTD_isError(ret)) { + if (ZSTD_isError(zstd_ret)) { ret = -EIO; break; } @@ -286,7 +289,7 @@ static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size, /* * Sanity check that each time we do some progress */ - if (last_input_pos >= input.pos) { + if (last_progress >= input.pos + output.pos) { ret = -EIO; break; } @@ -297,7 +300,7 @@ static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size, * if not, we somehow managed to get uncompressed cluster * greater then the cluster size. */ - if (ret > 0) { + if (zstd_ret > 0) { ret = -EIO; }
On 31.03.2020 17:49, Vladimir Sementsov-Ogievskiy wrote: > 31.03.2020 16:17, Denis Plotnikov wrote: >> 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 <dplotnikov@virtuozzo.com> >> QAPI part: >> Acked-by: Markus Armbruster <armbru@redhat.com> >> --- > > Hi! > > I have three suggestions: > > 1. return type of qcow2 compression functions is ssize_t, and return > type of zstd is size_t. I think better is not to mix them. > 2. safe check for ENOMEM in compression part - avoid overflow ( > maximum of paranoia :) > 3. slightly more tolerate sanity check in decompression part: allow > zstd to make progress only on one of the buffers > > Here is it, and if you like it, take it together with my > Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > > diff --git a/block/qcow2-threads.c b/block/qcow2-threads.c > index 0b04f30bd8..208218c8f3 100644 > --- a/block/qcow2-threads.c > +++ b/block/qcow2-threads.c > @@ -188,7 +188,7 @@ static ssize_t qcow2_zlib_decompress(void *dest, > size_t dest_size, > static ssize_t qcow2_zstd_compress(void *dest, size_t dest_size, > const void *src, size_t src_size) > { > - size_t ret; > + ssize_t ret; > ZSTD_outBuffer output = { dest, dest_size, 0 }; > ZSTD_inBuffer input = { src, src_size, 0 }; > ZSTD_CCtx *cctx; > @@ -214,13 +214,14 @@ static ssize_t qcow2_zstd_compress(void *dest, > size_t dest_size, > * We want to use zstd streamed interface on decompression, > * as we won't know the exact size of the compressed data. > */ > - ret = ZSTD_compressStream2(cctx, &output, &input, ZSTD_e_end); > - if (ZSTD_isError(ret)) { > + size_t zstd_ret = ZSTD_compressStream2(cctx, &output, &input, > + ZSTD_e_end); > + if (ZSTD_isError(zstd_ret)) { > ret = -EIO; > goto out; > } > /* Dest buffer isn't big enough to store compressed content */ > - if (output.pos + ret > output.size) { > + if (zstd_ret > output.size - output.pos) { > ret = -ENOMEM; > goto out; > } I'll apply this part as you suggested > @@ -248,7 +249,8 @@ out: > static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size, > const void *src, size_t src_size) > { > - size_t ret = 0; > + ssize_t ret = 0; > + size_t zstd_ret = 0; > ZSTD_outBuffer output = { dest, dest_size, 0 }; > ZSTD_inBuffer input = { src, src_size, 0 }; > ZSTD_DCtx *dctx = ZSTD_createDCtx(); > @@ -269,8 +271,9 @@ static ssize_t qcow2_zstd_decompress(void *dest, > size_t dest_size, > * ZSTD_decompressStream reads another ONE full frame. > */ > while (output.pos < output.size) { > - size_t last_input_pos = input.pos; > - ret = ZSTD_decompressStream(dctx, &output, &input); > + size_t last_progress = input.pos + output.pos; These two may overflow last_progress. In that case we have to check them in separate > + > + zstd_ret = ZSTD_decompressStream(dctx, &output, &input); > /* > * zstd manual doesn't explicitly states what happens, > * if the read the frame partially. But, based on the > @@ -278,7 +281,7 @@ static ssize_t qcow2_zstd_decompress(void *dest, > size_t dest_size, > * and have read all the frames from the input, > * we end up with error here. > */ > - if (ZSTD_isError(ret)) { > + if (ZSTD_isError(zstd_ret)) { > ret = -EIO; > break; > } > @@ -286,7 +289,7 @@ static ssize_t qcow2_zstd_decompress(void *dest, > size_t dest_size, > /* > * Sanity check that each time we do some progress > */ > - if (last_input_pos >= input.pos) { > + if (last_progress >= input.pos + output.pos) { > ret = -EIO; > break; > } > @@ -297,7 +300,7 @@ static ssize_t qcow2_zstd_decompress(void *dest, > size_t dest_size, > * if not, we somehow managed to get uncompressed cluster > * greater then the cluster size. > */ > - if (ret > 0) { > + if (zstd_ret > 0) { > ret = -EIO; > } I'll apply the changes and resend the series. Thanks! > > > >
diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt index 640e0eca40..18a77f737e 100644 --- a/docs/interop/qcow2.txt +++ b/docs/interop/qcow2.txt @@ -209,6 +209,7 @@ version 2. Available compression type values: 0: zlib <https://www.zlib.net/> + 1: zstd <http://github.com/facebook/zstd> === Header padding === diff --git a/configure b/configure index e225a1e3ff..fdc991b010 100755 --- a/configure +++ b/configure @@ -1861,7 +1861,7 @@ disabled with --disable-FEATURE, default is enabled if available: lzfse support of lzfse compression library (for reading lzfse-compressed dmg images) zstd support for zstd compression library - (for migration compression) + (for migration compression and qcow2 cluster compression) seccomp seccomp support coroutine-pool coroutine freelist (better performance) glusterfs GlusterFS backend diff --git a/qapi/block-core.json b/qapi/block-core.json index d669ec0965..44690ed266 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 <http://zlib.net/> +# @zstd: zstd compression, see <http://github.com/facebook/zstd> # # Since: 5.0 ## { 'enum': 'Qcow2CompressionType', - 'data': [ 'zlib' ] } + 'data': [ 'zlib', { 'name': 'zstd', 'if': 'defined(CONFIG_ZSTD)' } ] } ## # @BlockdevCreateOptionsQcow2: diff --git a/block/qcow2-threads.c b/block/qcow2-threads.c index 7dbaf53489..0b04f30bd8 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" @@ -166,6 +171,141 @@ 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) +{ + size_t ret; + ZSTD_outBuffer output = { dest, dest_size, 0 }; + ZSTD_inBuffer input = { src, src_size, 0 }; + ZSTD_CCtx *cctx; + + /* make sure we can safely return compressed buffer size with ssize_t */ + assert(dest_size <= SSIZE_MAX); + + cctx = ZSTD_createCCtx(); + if (!cctx) { + return -EIO; + } + /* + * ZSTD spec: "You must continue calling ZSTD_compressStream2() + * with ZSTD_e_end until it returns 0, at which point you are + * free to start a new frame". + * In the loop, we try to compress all the data into one zstd frame. + * ZSTD_compressStream2 potentially can finish a frame earlier + * than the full input data is consumed. That's why we are looping + * until all the input data is consumed. + */ + do { + /* + * We want to use zstd streamed interface on decompression, + * as we won't know the exact size of the compressed data. + */ + ret = ZSTD_compressStream2(cctx, &output, &input, ZSTD_e_end); + if (ZSTD_isError(ret)) { + ret = -EIO; + goto out; + } + /* Dest buffer isn't big enough to store compressed content */ + if (output.pos + ret > output.size) { + ret = -ENOMEM; + goto out; + } + } while (ret || input.pos < input.size); + + ret = output.pos; + +out: + ZSTD_freeCCtx(cctx); + return ret; +} + +/* + * 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) +{ + size_t ret = 0; + ZSTD_outBuffer output = { dest, dest_size, 0 }; + ZSTD_inBuffer input = { src, src_size, 0 }; + ZSTD_DCtx *dctx = ZSTD_createDCtx(); + + if (!dctx) { + return -EIO; + } + + /* + * The compressed stream from input buffer may consist from more + * than one zstd frames. So we iterate until we get a fully + * uncompressed cluster. + * from zstd docs: acording to ZSTD_decompressStream: + * "return : 0 when a frame is completely decoded and fully flushed" + * We suppose that this means: each time ZSTD_decompressStream reads + * only ONE full frame and return 0 if and only if that frame + * is completely decoded and flushed. Only after returning 0, + * ZSTD_decompressStream reads another ONE full frame. + */ + while (output.pos < output.size) { + size_t last_input_pos = input.pos; + ret = ZSTD_decompressStream(dctx, &output, &input); + /* + * zstd manual doesn't explicitly states what happens, + * if the read the frame partially. But, based on the + * our tests, if we don't fully populate the output + * and have read all the frames from the input, + * we end up with error here. + */ + if (ZSTD_isError(ret)) { + ret = -EIO; + break; + } + + /* + * Sanity check that each time we do some progress + */ + if (last_input_pos >= input.pos) { + ret = -EIO; + break; + } + } + + /* + * Make sure that we have the frame fully flushed here + * if not, we somehow managed to get uncompressed cluster + * greater then the cluster size. + */ + if (ret > 0) { + ret = -EIO; + } + + ZSTD_freeDCtx(dctx); + return ret; +} +#endif + static int qcow2_compress_pool_func(void *opaque) { Qcow2CompressData *data = opaque; @@ -217,6 +357,11 @@ 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: abort(); } @@ -249,6 +394,11 @@ 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: abort(); } diff --git a/block/qcow2.c b/block/qcow2.c index 6cb000be19..3ae9624ba3 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1246,6 +1246,9 @@ static int validate_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: @@ -3478,6 +3481,10 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp) } switch (qcow2_opts->compression_type) { +#ifdef CONFIG_ZSTD + case QCOW2_COMPRESSION_TYPE_ZSTD: + break; +#endif default: error_setg(errp, "Unknown compression type"); goto out;
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 <dplotnikov@virtuozzo.com> QAPI part: Acked-by: Markus Armbruster <armbru@redhat.com> --- docs/interop/qcow2.txt | 1 + configure | 2 +- qapi/block-core.json | 3 +- block/qcow2-threads.c | 150 +++++++++++++++++++++++++++++++++++++++++ block/qcow2.c | 7 ++ 5 files changed, 161 insertions(+), 2 deletions(-)