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alistair23-linux/include/linux/raid/pq.h
Zhengyuan Liu f591df3cc6 md/raid6: fix algorithm choice under larger PAGE_SIZE 
There are several algorithms available for raid6 to generate xor and syndrome
parity, including basic int1, int2 ... int32 and SIMD optimized implementation
like sse and neon.  To test and choose the best algorithms at the initial
stage, we need provide enough disk data to feed the algorithms. However, the
disk number we provided depends on page size and gfmul table, seeing bellow:

    const int disks = (65536/PAGE_SIZE) + 2;

So when come to 64K PAGE_SIZE, there is only one data disk plus 2 parity disk,
as a result the chosed algorithm is not reliable. For example, on my arm64
machine with 64K page enabled, it will choose intx32 as the best one, although
the NEON implementation is better.

This patch tries to fix the problem by defining a constant raid6 disk number to
supporting arbitrary page size.

Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Zhengyuan Liu <liuzhengyuan@kylinos.cn>
Signed-off-by: Song Liu <songliubraving@fb.com>
2020-01-13 11:44:09 -08:00

198 lines
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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright 2003 H. Peter Anvin - All Rights Reserved
*
* ----------------------------------------------------------------------- */
#ifndef LINUX_RAID_RAID6_H
#define LINUX_RAID_RAID6_H
#ifdef __KERNEL__
/* Set to 1 to use kernel-wide empty_zero_page */
#define RAID6_USE_EMPTY_ZERO_PAGE 0
#include <linux/blkdev.h>
/* We need a pre-zeroed page... if we don't want to use the kernel-provided
one define it here */
#if RAID6_USE_EMPTY_ZERO_PAGE
# define raid6_empty_zero_page empty_zero_page
#else
extern const char raid6_empty_zero_page[PAGE_SIZE];
#endif
#else /* ! __KERNEL__ */
/* Used for testing in user space */
#include <errno.h>
#include <inttypes.h>
#include <stddef.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <sys/types.h>
/* Not standard, but glibc defines it */
#define BITS_PER_LONG __WORDSIZE
typedef uint8_t u8;
typedef uint16_t u16;
typedef uint32_t u32;
typedef uint64_t u64;
#ifndef PAGE_SIZE
# define PAGE_SIZE 4096
#endif
#ifndef PAGE_SHIFT
# define PAGE_SHIFT 12
#endif
extern const char raid6_empty_zero_page[PAGE_SIZE];
#define __init
#define __exit
#ifndef __attribute_const__
# define __attribute_const__ __attribute__((const))
#endif
#define noinline __attribute__((noinline))
#define preempt_enable()
#define preempt_disable()
#define cpu_has_feature(x) 1
#define enable_kernel_altivec()
#define disable_kernel_altivec()
#undef EXPORT_SYMBOL
#define EXPORT_SYMBOL(sym)
#undef EXPORT_SYMBOL_GPL
#define EXPORT_SYMBOL_GPL(sym)
#define MODULE_LICENSE(licence)
#define MODULE_DESCRIPTION(desc)
#define subsys_initcall(x)
#define module_exit(x)
#define IS_ENABLED(x) (x)
#define CONFIG_RAID6_PQ_BENCHMARK 1
#endif /* __KERNEL__ */
/* Routine choices */
struct raid6_calls {
void (*gen_syndrome)(int, size_t, void **);
void (*xor_syndrome)(int, int, int, size_t, void **);
int (*valid)(void); /* Returns 1 if this routine set is usable */
const char *name; /* Name of this routine set */
int prefer; /* Has special performance attribute */
};
/* Selected algorithm */
extern struct raid6_calls raid6_call;
/* Various routine sets */
extern const struct raid6_calls raid6_intx1;
extern const struct raid6_calls raid6_intx2;
extern const struct raid6_calls raid6_intx4;
extern const struct raid6_calls raid6_intx8;
extern const struct raid6_calls raid6_intx16;
extern const struct raid6_calls raid6_intx32;
extern const struct raid6_calls raid6_mmxx1;
extern const struct raid6_calls raid6_mmxx2;
extern const struct raid6_calls raid6_sse1x1;
extern const struct raid6_calls raid6_sse1x2;
extern const struct raid6_calls raid6_sse2x1;
extern const struct raid6_calls raid6_sse2x2;
extern const struct raid6_calls raid6_sse2x4;
extern const struct raid6_calls raid6_altivec1;
extern const struct raid6_calls raid6_altivec2;
extern const struct raid6_calls raid6_altivec4;
extern const struct raid6_calls raid6_altivec8;
extern const struct raid6_calls raid6_avx2x1;
extern const struct raid6_calls raid6_avx2x2;
extern const struct raid6_calls raid6_avx2x4;
extern const struct raid6_calls raid6_avx512x1;
extern const struct raid6_calls raid6_avx512x2;
extern const struct raid6_calls raid6_avx512x4;
extern const struct raid6_calls raid6_s390vx8;
extern const struct raid6_calls raid6_vpermxor1;
extern const struct raid6_calls raid6_vpermxor2;
extern const struct raid6_calls raid6_vpermxor4;
extern const struct raid6_calls raid6_vpermxor8;
struct raid6_recov_calls {
void (*data2)(int, size_t, int, int, void **);
void (*datap)(int, size_t, int, void **);
int (*valid)(void);
const char *name;
int priority;
};
extern const struct raid6_recov_calls raid6_recov_intx1;
extern const struct raid6_recov_calls raid6_recov_ssse3;
extern const struct raid6_recov_calls raid6_recov_avx2;
extern const struct raid6_recov_calls raid6_recov_avx512;
extern const struct raid6_recov_calls raid6_recov_s390xc;
extern const struct raid6_recov_calls raid6_recov_neon;
extern const struct raid6_calls raid6_neonx1;
extern const struct raid6_calls raid6_neonx2;
extern const struct raid6_calls raid6_neonx4;
extern const struct raid6_calls raid6_neonx8;
/* Algorithm list */
extern const struct raid6_calls * const raid6_algos[];
extern const struct raid6_recov_calls *const raid6_recov_algos[];
int raid6_select_algo(void);
/* Return values from chk_syndrome */
#define RAID6_OK 0
#define RAID6_P_BAD 1
#define RAID6_Q_BAD 2
#define RAID6_PQ_BAD 3
/* Galois field tables */
extern const u8 raid6_gfmul[256][256] __attribute__((aligned(256)));
extern const u8 raid6_vgfmul[256][32] __attribute__((aligned(256)));
extern const u8 raid6_gfexp[256] __attribute__((aligned(256)));
extern const u8 raid6_gflog[256] __attribute__((aligned(256)));
extern const u8 raid6_gfinv[256] __attribute__((aligned(256)));
extern const u8 raid6_gfexi[256] __attribute__((aligned(256)));
/* Recovery routines */
extern void (*raid6_2data_recov)(int disks, size_t bytes, int faila, int failb,
void **ptrs);
extern void (*raid6_datap_recov)(int disks, size_t bytes, int faila,
void **ptrs);
void raid6_dual_recov(int disks, size_t bytes, int faila, int failb,
void **ptrs);
/* Some definitions to allow code to be compiled for testing in userspace */
#ifndef __KERNEL__
# define jiffies raid6_jiffies()
# define printk printf
# define pr_err(format, ...) fprintf(stderr, format, ## __VA_ARGS__)
# define pr_info(format, ...) fprintf(stdout, format, ## __VA_ARGS__)
# define GFP_KERNEL 0
# define __get_free_pages(x, y) ((unsigned long)mmap(NULL, PAGE_SIZE << (y), \
PROT_READ|PROT_WRITE, \
MAP_PRIVATE|MAP_ANONYMOUS,\
0, 0))
# define free_pages(x, y) munmap((void *)(x), PAGE_SIZE << (y))
static inline void cpu_relax(void)
{
/* Nothing */
}
#undef HZ
#define HZ 1000
static inline uint32_t raid6_jiffies(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return tv.tv_sec*1000 + tv.tv_usec/1000;
}
#endif /* ! __KERNEL__ */
#endif /* LINUX_RAID_RAID6_H */
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