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Diffstat (limited to '')
| -rw-r--r-- | lib/raid6/algos.c | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c new file mode 100644 index 000000000..39b74221f --- /dev/null +++ b/lib/raid6/algos.c @@ -0,0 +1,281 @@ +// 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, 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, best = NULL, algo = raid6_algos; *algo; algo++) { + if (!best || (*algo)->priority >= best->priority) { + 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 (!best) { + pr_err("raid6: Yikes! No algorithm found!\n"); + goto out; + } + + raid6_call = *best; + + if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) { + pr_info("raid6: skipped pq benchmark and selected %s\n", + best->name); + goto out; + } + + 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) { + perf = 0; + + preempt_disable(); + j0 = jiffies; + while ((j1 = jiffies) == j0) + cpu_relax(); + while (time_before(jiffies, + j1 + (1 << RAID6_TIME_JIFFIES_LG2))) { + best->xor_syndrome(disks, start, stop, + PAGE_SIZE, *dptrs); + perf++; + } + preempt_enable(); + + pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n", + (perf * HZ * (disks - 2)) >> + (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1)); + } + +out: + 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"); |