• Sven Schmidt's avatar
    lib: update LZ4 compressor module · 4e1a33b1
    Sven Schmidt authored
    Patch series "Update LZ4 compressor module", v7.
    This patchset updates the LZ4 compression module to a version based on
    LZ4 v1.7.3 allowing to use the fast compression algorithm aka LZ4 fast
    which provides an "acceleration" parameter as a tradeoff between high
    compression ratio and high compression speed.
    We want to use LZ4 fast in order to support compression in lustre and
    (mostly, based on that) investigate data reduction techniques in behalf
    of storage systems.
    Also, it will be useful for other users of LZ4 compression, as with LZ4
    fast it is possible to enable applications to use fast and/or high
    compression depending on the usecase.  For instance, ZRAM is offering a
    LZ4 backend and could benefit from an updated LZ4 in the kernel.
    LZ4 homepage: http://www.lz4.org/
    LZ4 source repository: https://github.com/lz4/lz4 Source version: 1.7.3
    Benchmark (taken from [1], Core i5-4300U @1.9GHz):
    Compressor      | Compression  | Decompression  | Ratio
    memcpy          |  4200 MB/s   |  4200 MB/s     | 1.000
    LZ4 fast 50     |  1080 MB/s   |  2650 MB/s     | 1.375
    LZ4 fast 17     |   680 MB/s   |  2220 MB/s     | 1.607
    LZ4 fast 5      |   475 MB/s   |  1920 MB/s     | 1.886
    LZ4 default     |   385 MB/s   |  1850 MB/s     | 2.101
    [1] http://fastcompression.blogspot.de/2015/04/sampling-or-faster-lz4.html
    [PATCH 1/5] lib: Update LZ4 compressor module
    [PATCH 2/5] lib/decompress_unlz4: Change module to work with new LZ4 module version
    [PATCH 3/5] crypto: Change LZ4 modules to work with new LZ4 module version
    [PATCH 4/5] fs/pstore: fs/squashfs: Change usage of LZ4 to work with new LZ4 version
    [PATCH 5/5] lib/lz4: Remove back-compat wrappers
    This patch (of 5):
    Update the LZ4 kernel module to LZ4 v1.7.3 by Yann Collet.  The kernel
    module is inspired by the previous work by Chanho Min.  The updated LZ4
    module will not break existing code since the patchset contains
    appropriate changes.
    API changes:
    New method LZ4_compress_fast which differs from the variant available in
    kernel by the new acceleration parameter, allowing to trade compression
    ratio for more compression speed and vice versa.
    LZ4_decompress_fast is the respective decompression method, featuring a
    very fast decoder (multiple GB/s per core), able to reach RAM speed in
    multi-core systems.  The decompressor allows to decompress data
    compressed with LZ4 fast as well as the LZ4 HC (high compression)
    Also the useful functions LZ4_decompress_safe_partial and
    LZ4_compress_destsize were added.  The latter reverses the logic by
    trying to compress as much data as possible from source to dest while
    the former aims to decompress partial blocks of data.
    A bunch of streaming functions were also added which allow
    compressig/decompressing data in multiple steps (so called "streaming
    The methods lz4_compress and lz4_decompress_unknownoutputsize are now
    known as LZ4_compress_default respectivley LZ4_decompress_safe.  The old
    methods will be removed since there's no callers left in the code.
    [arnd@arndb.de: fix KERNEL_LZ4 support]
      Link: http://lkml.kernel.org/r/20170208211946.2839649-1-arnd@arndb.de
    [akpm@linux-foundation.org: simplify]
    [akpm@linux-foundation.org: fix the simplification]
    [4sschmid@informatik.uni-hamburg.de: fix performance regressions]
      Link: http://lkml.kernel.org/r/1486898178-17125-2-git-send-email-4sschmid@informatik.uni-hamburg.de
    [4sschmid@informatik.uni-hamburg.de: v8]
      Link: http://lkml.kernel.org/r/1487182598-15351-2-git-send-email-4sschmid@informatik.uni-hamburg.de
    Link: http://lkml.kernel.org/r/1486321748-19085-2-git-send-email-4sschmid@informatik.uni-hamburg.deSigned-off-by: default avatarSven Schmidt <4sschmid@informatik.uni-hamburg.de>
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    Cc: Bongkyu Kim <bongkyu.kim@lge.com>
    Cc: Rui Salvaterra <rsalvaterra@gmail.com>
    Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Herbert Xu <herbert@gondor.apana.org.au>
    Cc: David S. Miller <davem@davemloft.net>
    Cc: Anton Vorontsov <anton@enomsg.org>
    Cc: Colin Cross <ccross@android.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Tony Luck <tony.luck@intel.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Makefile 161 Bytes