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// SPDX-License-Identifier: GPL-2.0-or-later
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright 2002 H. Peter Anvin - All Rights Reserved
*
* ----------------------------------------------------------------------- */
/*
* raid6/algos.c
*
* Algorithm list and algorithm selection for RAID-6
*/
#include <linux/raid/pq.h>
#ifndef __KERNEL__
#include <sys/mman.h>
#include <stdio.h>
#else
#include <linux/module.h>
#include <linux/gfp.h>
#if !RAID6_USE_EMPTY_ZERO_PAGE
/* In .bss so it's zeroed */
const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
EXPORT_SYMBOL(raid6_empty_zero_page);
#endif
#endif
struct raid6_calls raid6_call;
EXPORT_SYMBOL_GPL(raid6_call);
const struct raid6_calls * const raid6_algos[] = {
#if defined(__i386__) && !defined(__arch_um__)
#ifdef CONFIG_AS_AVX512
&raid6_avx512x2,
&raid6_avx512x1,
#endif
&raid6_avx2x2,
&raid6_avx2x1,
&raid6_sse2x2,
&raid6_sse2x1,
&raid6_sse1x2,
&raid6_sse1x1,
&raid6_mmxx2,
&raid6_mmxx1,
#endif
#if defined(__x86_64__) && !defined(__arch_um__)
#ifdef CONFIG_AS_AVX512
&raid6_avx512x4,
&raid6_avx512x2,
&raid6_avx512x1,
#endif
&raid6_avx2x4,
&raid6_avx2x2,
&raid6_avx2x1,
&raid6_sse2x4,
&raid6_sse2x2,
&raid6_sse2x1,
#endif
#ifdef CONFIG_ALTIVEC
&raid6_vpermxor8,
&raid6_vpermxor4,
&raid6_vpermxor2,
&raid6_vpermxor1,
&raid6_altivec8,
&raid6_altivec4,
&raid6_altivec2,
&raid6_altivec1,
#endif
#if defined(CONFIG_S390)
&raid6_s390vx8,
#endif
#ifdef CONFIG_KERNEL_MODE_NEON
&raid6_neonx8,
&raid6_neonx4,
&raid6_neonx2,
&raid6_neonx1,
#endif
#if defined(__ia64__)
&raid6_intx32,
&raid6_intx16,
#endif
&raid6_intx8,
&raid6_intx4,
&raid6_intx2,
&raid6_intx1,
NULL
};
void (*raid6_2data_recov)(int, size_t, int, int, void **);
EXPORT_SYMBOL_GPL(raid6_2data_recov);
void (*raid6_datap_recov)(int, size_t, int, void **);
EXPORT_SYMBOL_GPL(raid6_datap_recov);
const struct raid6_recov_calls *const raid6_recov_algos[] = {
#ifdef CONFIG_X86
#ifdef CONFIG_AS_AVX512
&raid6_recov_avx512,
#endif
&raid6_recov_avx2,
&raid6_recov_ssse3,
#endif
#ifdef CONFIG_S390
&raid6_recov_s390xc,
#endif
#if defined(CONFIG_KERNEL_MODE_NEON)
&raid6_recov_neon,
#endif
&raid6_recov_intx1,
NULL
};
#ifdef __KERNEL__
#define RAID6_TIME_JIFFIES_LG2 4
#else
/* Need more time to be stable in userspace */
#define RAID6_TIME_JIFFIES_LG2 9
#define time_before(x, y) ((x) < (y))
#endif
#define RAID6_TEST_DISKS 8
#define RAID6_TEST_DISKS_ORDER 3
static inline const struct raid6_recov_calls *raid6_choose_recov(void)
{
const struct raid6_recov_calls *const *algo;
const struct raid6_recov_calls *best;
for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
if (!best || (*algo)->priority > best->priority)
if (!(*algo)->valid || (*algo)->valid())
best = *algo;
if (best) {
raid6_2data_recov = best->data2;
raid6_datap_recov = best->datap;
pr_info("raid6: using %s recovery algorithm\n", best->name);
} else
pr_err("raid6: Yikes! No recovery algorithm found!\n");
return best;
}
static inline const struct raid6_calls *raid6_choose_gen(
void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
{
unsigned long perf, bestgenperf, bestxorperf, j0, j1;
int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
const struct raid6_calls *const *algo;
const struct raid6_calls *best;
for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
if (!best || (*algo)->prefer >= best->prefer) {
if ((*algo)->valid && !(*algo)->valid())
continue;
if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
best = *algo;
break;
}
perf = 0;
preempt_disable();
j0 = jiffies;
while ((j1 = jiffies) == j0)
cpu_relax();
while (time_before(jiffies,
j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
(*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
perf++;
}
preempt_enable();
if (perf > bestgenperf) {
bestgenperf = perf;
best = *algo;
}
pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
(perf * HZ * (disks-2)) >>
(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
if (!(*algo)->xor_syndrome)
continue;
perf = 0;
preempt_disable();
j0 = jiffies;
while ((j1 = jiffies) == j0)
cpu_relax();
while (time_before(jiffies,
j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
(*algo)->xor_syndrome(disks, start, stop,
PAGE_SIZE, *dptrs);
perf++;
}
preempt_enable();
if (best == *algo)
bestxorperf = perf;
pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
(perf * HZ * (disks-2)) >>
(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
}
}
if (best) {
if (IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
best->name,
(bestgenperf * HZ * (disks-2)) >>
(20 - PAGE_SHIFT+RAID6_TIME_JIFFIES_LG2));
if (best->xor_syndrome)
pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
(bestxorperf * HZ * (disks-2)) >>
(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
} else
pr_info("raid6: skip pq benchmark and using algorithm %s\n",
best->name);
raid6_call = *best;
} else
pr_err("raid6: Yikes! No algorithm found!\n");
return best;
}
/* Try to pick the best algorithm */
/* This code uses the gfmul table as convenient data set to abuse */
int __init raid6_select_algo(void)
{
const int disks = RAID6_TEST_DISKS;
const struct raid6_calls *gen_best;
const struct raid6_recov_calls *rec_best;
char *disk_ptr, *p;
void *dptrs[RAID6_TEST_DISKS];
int i, cycle;
/* prepare the buffer and fill it circularly with gfmul table */
disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
if (!disk_ptr) {
pr_err("raid6: Yikes! No memory available.\n");
return -ENOMEM;
}
p = disk_ptr;
for (i = 0; i < disks; i++)
dptrs[i] = p + PAGE_SIZE * i;
cycle = ((disks - 2) * PAGE_SIZE) / 65536;
for (i = 0; i < cycle; i++) {
memcpy(p, raid6_gfmul, 65536);
p += 65536;
}
if ((disks - 2) * PAGE_SIZE % 65536)
memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
/* select raid gen_syndrome function */
gen_best = raid6_choose_gen(&dptrs, disks);
/* select raid recover functions */
rec_best = raid6_choose_recov();
free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
return gen_best && rec_best ? 0 : -EINVAL;
}
static void raid6_exit(void)
{
do { } while (0);
}
subsys_initcall(raid6_select_algo);
module_exit(raid6_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
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