this adds support for optimized zlib settings which almost tripples the compression speed while maintaining about the same compressed size.
Signed-off-by: Peter Lieven <p...@kamp.de> --- block/qcow2-cluster.c | 3 ++- block/qcow2.c | 11 +++++++++-- block/qcow2.h | 1 + qemu-img.texi | 1 + 4 files changed, 13 insertions(+), 3 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index ecb059b..d8e2378 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1532,6 +1532,7 @@ static int decompress_buffer(uint8_t *out_buf, int out_buf_size, switch (compression_algorithm_id) { case QCOW2_COMPRESSION_ZLIB: + case QCOW2_COMPRESSION_ZLIB_FAST: memset(strm, 0, sizeof(*strm)); strm->next_in = (uint8_t *)buf; @@ -1539,7 +1540,7 @@ static int decompress_buffer(uint8_t *out_buf, int out_buf_size, strm->next_out = out_buf; strm->avail_out = out_buf_size; - ret = inflateInit2(strm, -12); + ret = inflateInit2(strm, -15); if (ret != Z_OK) { return -1; } diff --git a/block/qcow2.c b/block/qcow2.c index bd65582..f07d8f0 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -87,6 +87,8 @@ static uint32_t is_compression_algorithm_supported(char *algorithm) /* no algorithm means the old default of zlib compression * with 12 window bits */ return QCOW2_COMPRESSION_ZLIB; + } else if (!strcmp(algorithm, "zlib-fast")) { + return QCOW2_COMPRESSION_ZLIB_FAST; #ifdef CONFIG_LZO } else if (!strcmp(algorithm, "lzo")) { return QCOW2_COMPRESSION_LZO; @@ -2722,6 +2724,7 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, QEMUIOVector hd_qiov; struct iovec iov; z_stream strm; + int z_level = Z_DEFAULT_COMPRESSION, z_windowBits = -12; int ret, out_len = 0; uint8_t *buf, *out_buf = NULL, *local_buf = NULL, *work_buf = NULL; uint64_t cluster_offset; @@ -2749,13 +2752,17 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, } switch (s->compression_algorithm_id) { + case QCOW2_COMPRESSION_ZLIB_FAST: + z_level = Z_BEST_SPEED; + z_windowBits = -15; + /* fall-through */ case QCOW2_COMPRESSION_ZLIB: out_buf = g_malloc(s->cluster_size); /* best compression, small window, no zlib header */ memset(&strm, 0, sizeof(strm)); - ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, - Z_DEFLATED, -12, + ret = deflateInit2(&strm, z_level, + Z_DEFLATED, z_windowBits, 9, Z_DEFAULT_STRATEGY); if (ret != 0) { ret = -EINVAL; diff --git a/block/qcow2.h b/block/qcow2.h index 716012c..a89f986 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -173,6 +173,7 @@ typedef struct Qcow2UnknownHeaderExtension { enum { QCOW2_COMPRESSION_ZLIB = 0xC0318301, QCOW2_COMPRESSION_LZO = 0xC0318302, + QCOW2_COMPRESSION_ZLIB_FAST = 0xC0318303, }; enum { diff --git a/qemu-img.texi b/qemu-img.texi index 043c1ba..83a5db2 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -627,6 +627,7 @@ The following options are available if support for the respective libraries has been enabled at compile time: zlib Uses standard zlib compression (default) + zlib-fast Uses zlib compression with optimized compression parameters lzo Uses LZO1X compression The compression algorithm can only be defined at image create time and cannot -- 1.9.1