Commit 5d240522 authored by Nick Terrell's avatar Nick Terrell Committed by Chris Mason

lib: Add xxhash module

Adds xxhash kernel module with xxh32 and xxh64 hashes. xxhash is an
extremely fast non-cryptographic hash algorithm for checksumming.
The zstd compression and decompression modules added in the next patch
require xxhash. I extracted it out from zstd since it is useful on its
own. I copied the code from the upstream XXHash source repository and
translated it into kernel style. I ran benchmarks and tests in the kernel
and tests in userland.

I benchmarked xxhash as a special character device. I ran in four modes,
no-op, xxh32, xxh64, and crc32. The no-op mode simply copies the data to
kernel space and ignores it. The xxh32, xxh64, and crc32 modes compute
hashes on the copied data. I also ran it with four different buffer sizes.
The benchmark file is located in the upstream zstd source repository under
`contrib/linux-kernel/xxhash_test.c` [1].

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. I benchmarked using the file `filesystem.squashfs`
from `ubuntu-16.10-desktop-amd64.iso`, which is 1,536,217,088 B large.
Run the following commands for the benchmark:

    modprobe xxhash_test
    mknod xxhash_test c 245 0
    time cp filesystem.squashfs xxhash_test

The time is reported by the time of the userland `cp`.
The GB/s is computed with

    1,536,217,008 B / time(buffer size, hash)

which includes the time to copy from userland.
The Normalized GB/s is computed with

    1,536,217,088 B / (time(buffer size, hash) - time(buffer size, none)).

| Buffer Size (B) | Hash  | Time (s) | GB/s | Adjusted GB/s |
|-----------------|-------|----------|------|---------------|
|            1024 | none  |    0.408 | 3.77 |             - |
|            1024 | xxh32 |    0.649 | 2.37 |          6.37 |
|            1024 | xxh64 |    0.542 | 2.83 |         11.46 |
|            1024 | crc32 |    1.290 | 1.19 |          1.74 |
|            4096 | none  |    0.380 | 4.04 |             - |
|            4096 | xxh32 |    0.645 | 2.38 |          5.79 |
|            4096 | xxh64 |    0.500 | 3.07 |         12.80 |
|            4096 | crc32 |    1.168 | 1.32 |          1.95 |
|            8192 | none  |    0.351 | 4.38 |             - |
|            8192 | xxh32 |    0.614 | 2.50 |          5.84 |
|            8192 | xxh64 |    0.464 | 3.31 |         13.60 |
|            8192 | crc32 |    1.163 | 1.32 |          1.89 |
|           16384 | none  |    0.346 | 4.43 |             - |
|           16384 | xxh32 |    0.590 | 2.60 |          6.30 |
|           16384 | xxh64 |    0.466 | 3.30 |         12.80 |
|           16384 | crc32 |    1.183 | 1.30 |          1.84 |

Tested in userland using the test-suite in the zstd repo under
`contrib/linux-kernel/test/XXHashUserlandTest.cpp` [2] by mocking the
kernel functions. A line in each branch of every function in `xxhash.c`
was commented out to ensure that the test-suite fails. Additionally
tested while testing zstd and with SMHasher [3].

[1] https://phabricator.intern.facebook.com/P57526246
[2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/XXHashUserlandTest.cpp
[3] https://github.com/aappleby/smhasher

zstd source repository: https://github.com/facebook/zstd
XXHash source repository: https://github.com/cyan4973/xxhashSigned-off-by: default avatarNick Terrell <terrelln@fb.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent ef954844
/*
* xxHash - Extremely Fast Hash algorithm
* Copyright (C) 2012-2016, Yann Collet.
*
* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License version 2 as published by the
* Free Software Foundation. This program is dual-licensed; you may select
* either version 2 of the GNU General Public License ("GPL") or BSD license
* ("BSD").
*
* You can contact the author at:
* - xxHash homepage: http://cyan4973.github.io/xxHash/
* - xxHash source repository: https://github.com/Cyan4973/xxHash
*/
/*
* Notice extracted from xxHash homepage:
*
* xxHash is an extremely fast Hash algorithm, running at RAM speed limits.
* It also successfully passes all tests from the SMHasher suite.
*
* Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2
* Duo @3GHz)
*
* Name Speed Q.Score Author
* xxHash 5.4 GB/s 10
* CrapWow 3.2 GB/s 2 Andrew
* MumurHash 3a 2.7 GB/s 10 Austin Appleby
* SpookyHash 2.0 GB/s 10 Bob Jenkins
* SBox 1.4 GB/s 9 Bret Mulvey
* Lookup3 1.2 GB/s 9 Bob Jenkins
* SuperFastHash 1.2 GB/s 1 Paul Hsieh
* CityHash64 1.05 GB/s 10 Pike & Alakuijala
* FNV 0.55 GB/s 5 Fowler, Noll, Vo
* CRC32 0.43 GB/s 9
* MD5-32 0.33 GB/s 10 Ronald L. Rivest
* SHA1-32 0.28 GB/s 10
*
* Q.Score is a measure of quality of the hash function.
* It depends on successfully passing SMHasher test set.
* 10 is a perfect score.
*
* A 64-bits version, named xxh64 offers much better speed,
* but for 64-bits applications only.
* Name Speed on 64 bits Speed on 32 bits
* xxh64 13.8 GB/s 1.9 GB/s
* xxh32 6.8 GB/s 6.0 GB/s
*/
#ifndef XXHASH_H
#define XXHASH_H
#include <linux/types.h>
/*-****************************
* Simple Hash Functions
*****************************/
/**
* xxh32() - calculate the 32-bit hash of the input with a given seed.
*
* @input: The data to hash.
* @length: The length of the data to hash.
* @seed: The seed can be used to alter the result predictably.
*
* Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s
*
* Return: The 32-bit hash of the data.
*/
uint32_t xxh32(const void *input, size_t length, uint32_t seed);
/**
* xxh64() - calculate the 64-bit hash of the input with a given seed.
*
* @input: The data to hash.
* @length: The length of the data to hash.
* @seed: The seed can be used to alter the result predictably.
*
* This function runs 2x faster on 64-bit systems, but slower on 32-bit systems.
*
* Return: The 64-bit hash of the data.
*/
uint64_t xxh64(const void *input, size_t length, uint64_t seed);
/*-****************************
* Streaming Hash Functions
*****************************/
/*
* These definitions are only meant to allow allocation of XXH state
* statically, on stack, or in a struct for example.
* Do not use members directly.
*/
/**
* struct xxh32_state - private xxh32 state, do not use members directly
*/
struct xxh32_state {
uint32_t total_len_32;
uint32_t large_len;
uint32_t v1;
uint32_t v2;
uint32_t v3;
uint32_t v4;
uint32_t mem32[4];
uint32_t memsize;
};
/**
* struct xxh32_state - private xxh64 state, do not use members directly
*/
struct xxh64_state {
uint64_t total_len;
uint64_t v1;
uint64_t v2;
uint64_t v3;
uint64_t v4;
uint64_t mem64[4];
uint32_t memsize;
};
/**
* xxh32_reset() - reset the xxh32 state to start a new hashing operation
*
* @state: The xxh32 state to reset.
* @seed: Initialize the hash state with this seed.
*
* Call this function on any xxh32_state to prepare for a new hashing operation.
*/
void xxh32_reset(struct xxh32_state *state, uint32_t seed);
/**
* xxh32_update() - hash the data given and update the xxh32 state
*
* @state: The xxh32 state to update.
* @input: The data to hash.
* @length: The length of the data to hash.
*
* After calling xxh32_reset() call xxh32_update() as many times as necessary.
*
* Return: Zero on success, otherwise an error code.
*/
int xxh32_update(struct xxh32_state *state, const void *input, size_t length);
/**
* xxh32_digest() - produce the current xxh32 hash
*
* @state: Produce the current xxh32 hash of this state.
*
* A hash value can be produced at any time. It is still possible to continue
* inserting input into the hash state after a call to xxh32_digest(), and
* generate new hashes later on, by calling xxh32_digest() again.
*
* Return: The xxh32 hash stored in the state.
*/
uint32_t xxh32_digest(const struct xxh32_state *state);
/**
* xxh64_reset() - reset the xxh64 state to start a new hashing operation
*
* @state: The xxh64 state to reset.
* @seed: Initialize the hash state with this seed.
*/
void xxh64_reset(struct xxh64_state *state, uint64_t seed);
/**
* xxh64_update() - hash the data given and update the xxh64 state
* @state: The xxh64 state to update.
* @input: The data to hash.
* @length: The length of the data to hash.
*
* After calling xxh64_reset() call xxh64_update() as many times as necessary.
*
* Return: Zero on success, otherwise an error code.
*/
int xxh64_update(struct xxh64_state *state, const void *input, size_t length);
/**
* xxh64_digest() - produce the current xxh64 hash
*
* @state: Produce the current xxh64 hash of this state.
*
* A hash value can be produced at any time. It is still possible to continue
* inserting input into the hash state after a call to xxh64_digest(), and
* generate new hashes later on, by calling xxh64_digest() again.
*
* Return: The xxh64 hash stored in the state.
*/
uint64_t xxh64_digest(const struct xxh64_state *state);
/*-**************************
* Utils
***************************/
/**
* xxh32_copy_state() - copy the source state into the destination state
*
* @src: The source xxh32 state.
* @dst: The destination xxh32 state.
*/
void xxh32_copy_state(struct xxh32_state *dst, const struct xxh32_state *src);
/**
* xxh64_copy_state() - copy the source state into the destination state
*
* @src: The source xxh64 state.
* @dst: The destination xxh64 state.
*/
void xxh64_copy_state(struct xxh64_state *dst, const struct xxh64_state *src);
#endif /* XXHASH_H */
...@@ -192,6 +192,9 @@ config CRC8 ...@@ -192,6 +192,9 @@ config CRC8
when they need to do cyclic redundancy check according CRC8 when they need to do cyclic redundancy check according CRC8
algorithm. Module will be called crc8. algorithm. Module will be called crc8.
config XXHASH
tristate
config AUDIT_GENERIC config AUDIT_GENERIC
bool bool
depends on AUDIT && !AUDIT_ARCH depends on AUDIT && !AUDIT_ARCH
......
...@@ -102,6 +102,7 @@ obj-$(CONFIG_CRC4) += crc4.o ...@@ -102,6 +102,7 @@ obj-$(CONFIG_CRC4) += crc4.o
obj-$(CONFIG_CRC7) += crc7.o obj-$(CONFIG_CRC7) += crc7.o
obj-$(CONFIG_LIBCRC32C) += libcrc32c.o obj-$(CONFIG_LIBCRC32C) += libcrc32c.o
obj-$(CONFIG_CRC8) += crc8.o obj-$(CONFIG_CRC8) += crc8.o
obj-$(CONFIG_XXHASH) += xxhash.o
obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o
obj-$(CONFIG_842_COMPRESS) += 842/ obj-$(CONFIG_842_COMPRESS) += 842/
......
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