87bf54bb43
Add zstd compression and decompression support to SquashFS. zstd is a great fit for SquashFS because it can compress at ratios approaching xz, while decompressing twice as fast as zlib. For SquashFS in particular, it can decompress as fast as lzo and lz4. It also has the flexibility to turn down the compression ratio for faster compression times. The compression benchmark is run on the file tree from the SquashFS archive found in ubuntu-16.10-desktop-amd64.iso [1]. It uses `mksquashfs` with the default block size (128 KB) and and various compression algorithms/levels. xz and zstd are also benchmarked with 256 KB blocks. The decompression benchmark times how long it takes to `tar` the file tree into `/dev/null`. See the benchmark file in the upstream zstd source repository located under `contrib/linux-kernel/squashfs-benchmark.sh` [2] for details. I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM. The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor, 16 GB of RAM, and a SSD. | Method | Ratio | Compression MB/s | Decompression MB/s | |----------------|-------|------------------|--------------------| | gzip | 2.92 | 15 | 128 | | lzo | 2.64 | 9.5 | 217 | | lz4 | 2.12 | 94 | 218 | | xz | 3.43 | 5.5 | 35 | | xz 256 KB | 3.53 | 5.4 | 40 | | zstd 1 | 2.71 | 96 | 210 | | zstd 5 | 2.93 | 69 | 198 | | zstd 10 | 3.01 | 41 | 225 | | zstd 15 | 3.13 | 11.4 | 224 | | zstd 16 256 KB | 3.24 | 8.1 | 210 | This patch was written by Sean Purcell <me@seanp.xyz>, but I will be taking over the submission process. [1] http://releases.ubuntu.com/16.10/ [2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/squashfs-benchmark.sh zstd source repository: https://github.com/facebook/zstd Signed-off-by: Sean Purcell <me@seanp.xyz> Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Chris Mason <clm@fb.com> Acked-by: Phillip Lougher <phillip@squashfs.org.uk>
65 lines
2 KiB
C
65 lines
2 KiB
C
#ifndef DECOMPRESSOR_H
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#define DECOMPRESSOR_H
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/*
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* Squashfs - a compressed read only filesystem for Linux
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*
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* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2,
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* or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* decompressor.h
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*/
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struct squashfs_decompressor {
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void *(*init)(struct squashfs_sb_info *, void *);
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void *(*comp_opts)(struct squashfs_sb_info *, void *, int);
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void (*free)(void *);
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int (*decompress)(struct squashfs_sb_info *, void *,
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struct buffer_head **, int, int, int,
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struct squashfs_page_actor *);
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int id;
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char *name;
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int supported;
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};
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static inline void *squashfs_comp_opts(struct squashfs_sb_info *msblk,
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void *buff, int length)
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{
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return msblk->decompressor->comp_opts ?
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msblk->decompressor->comp_opts(msblk, buff, length) : NULL;
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}
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#ifdef CONFIG_SQUASHFS_XZ
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extern const struct squashfs_decompressor squashfs_xz_comp_ops;
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#endif
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#ifdef CONFIG_SQUASHFS_LZ4
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extern const struct squashfs_decompressor squashfs_lz4_comp_ops;
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#endif
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#ifdef CONFIG_SQUASHFS_LZO
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extern const struct squashfs_decompressor squashfs_lzo_comp_ops;
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#endif
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#ifdef CONFIG_SQUASHFS_ZLIB
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extern const struct squashfs_decompressor squashfs_zlib_comp_ops;
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#endif
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#ifdef CONFIG_SQUASHFS_ZSTD
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extern const struct squashfs_decompressor squashfs_zstd_comp_ops;
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#endif
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#endif
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