lib/raid6/algos.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* -*- linux-c -*- ------------------------------------------------------- *
   3  *
   4  *   Copyright 2002 H. Peter Anvin - All Rights Reserved
   5  *
   6  * ----------------------------------------------------------------------- */
   7
   8 /*
   9  * raid6/algos.c
  10  *
  11  * Algorithm list and algorithm selection for RAID-6
  12  */
  13
  14 #include <linux/raid/pq.h>
  15 #ifndef __KERNEL__
  16 #include <sys/mman.h>
  17 #include <stdio.h>
  18 #else
  19 #include <linux/module.h>
  20 #include <linux/gfp.h>
  21 #if !RAID6_USE_EMPTY_ZERO_PAGE
  22 /* In .bss so it's zeroed */
  23 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
  24 EXPORT_SYMBOL(raid6_empty_zero_page);
  25 #endif
  26 #endif
  27
  28 struct raid6_calls raid6_call;
  29 EXPORT_SYMBOL_GPL(raid6_call);
  30
  31 const struct raid6_calls * const raid6_algos[] = {
  32 #if defined(__i386__) && !defined(__arch_um__)
  33 #ifdef CONFIG_AS_AVX512
  34         &raid6_avx512x2,
  35         &raid6_avx512x1,
  36 #endif
  37         &raid6_avx2x2,
  38         &raid6_avx2x1,
  39         &raid6_sse2x2,
  40         &raid6_sse2x1,
  41         &raid6_sse1x2,
  42         &raid6_sse1x1,
  43         &raid6_mmxx2,
  44         &raid6_mmxx1,
  45 #endif
  46 #if defined(__x86_64__) && !defined(__arch_um__)
  47 #ifdef CONFIG_AS_AVX512
  48         &raid6_avx512x4,
  49         &raid6_avx512x2,
  50         &raid6_avx512x1,
  51 #endif
  52         &raid6_avx2x4,
  53         &raid6_avx2x2,
  54         &raid6_avx2x1,
  55         &raid6_sse2x4,
  56         &raid6_sse2x2,
  57         &raid6_sse2x1,
  58 #endif
  59 #ifdef CONFIG_ALTIVEC
  60         &raid6_vpermxor8,
  61         &raid6_vpermxor4,
  62         &raid6_vpermxor2,
  63         &raid6_vpermxor1,
  64         &raid6_altivec8,
  65         &raid6_altivec4,
  66         &raid6_altivec2,
  67         &raid6_altivec1,
  68 #endif
  69 #if defined(CONFIG_S390)
  70         &raid6_s390vx8,
  71 #endif
  72 #ifdef CONFIG_KERNEL_MODE_NEON
  73         &raid6_neonx8,
  74         &raid6_neonx4,
  75         &raid6_neonx2,
  76         &raid6_neonx1,
  77 #endif
  78 #if defined(__ia64__)
  79         &raid6_intx32,
  80         &raid6_intx16,
  81 #endif
  82         &raid6_intx8,
  83         &raid6_intx4,
  84         &raid6_intx2,
  85         &raid6_intx1,
  86         NULL
  87 };
  88
  89 void (*raid6_2data_recov)(int, size_t, int, int, void **);
  90 EXPORT_SYMBOL_GPL(raid6_2data_recov);
  91
  92 void (*raid6_datap_recov)(int, size_t, int, void **);
  93 EXPORT_SYMBOL_GPL(raid6_datap_recov);
  94
  95 const struct raid6_recov_calls *const raid6_recov_algos[] = {
  96 #ifdef CONFIG_X86
  97 #ifdef CONFIG_AS_AVX512
  98         &raid6_recov_avx512,
  99 #endif
 100         &raid6_recov_avx2,
 101         &raid6_recov_ssse3,
 102 #endif
 103 #ifdef CONFIG_S390
 104         &raid6_recov_s390xc,
 105 #endif
 106 #if defined(CONFIG_KERNEL_MODE_NEON)
 107         &raid6_recov_neon,
 108 #endif
 109         &raid6_recov_intx1,
 110         NULL
 111 };
 112
 113 #ifdef __KERNEL__
 114 #define RAID6_TIME_JIFFIES_LG2  4
 115 #else
 116 /* Need more time to be stable in userspace */
 117 #define RAID6_TIME_JIFFIES_LG2  9
 118 #define time_before(x, y) ((x) < (y))
 119 #endif
 120
 121 #define RAID6_TEST_DISKS        8
 122 #define RAID6_TEST_DISKS_ORDER  3
 123
 124 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
 125 {
 126         const struct raid6_recov_calls *const *algo;
 127         const struct raid6_recov_calls *best;
 128
 129         for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
 130                 if (!best || (*algo)->priority > best->priority)
 131                         if (!(*algo)->valid || (*algo)->valid())
 132                                 best = *algo;
 133
 134         if (best) {
 135                 raid6_2data_recov = best->data2;
 136                 raid6_datap_recov = best->datap;
 137
 138                 pr_info("raid6: using %s recovery algorithm\n", best->name);
 139         } else
 140                 pr_err("raid6: Yikes! No recovery algorithm found!\n");
 141
 142         return best;
 143 }
 144
 145 static inline const struct raid6_calls *raid6_choose_gen(
 146         void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
 147 {
 148         unsigned long perf, bestgenperf, bestxorperf, j0, j1;
 149         int start = (disks>>1)-1, stop = disks-3;       /* work on the second half of the disks */
 150         const struct raid6_calls *const *algo;
 151         const struct raid6_calls *best;
 152
 153         for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
 154                 if (!best || (*algo)->prefer >= best->prefer) {
 155                         if ((*algo)->valid && !(*algo)->valid())
 156                                 continue;
 157
 158                         if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
 159                                 best = *algo;
 160                                 break;
 161                         }
 162
 163                         perf = 0;
 164
 165                         preempt_disable();
 166                         j0 = jiffies;
 167                         while ((j1 = jiffies) == j0)
 168                                 cpu_relax();
 169                         while (time_before(jiffies,
 170                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 171                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
 172                                 perf++;
 173                         }
 174                         preempt_enable();
 175
 176                         if (perf > bestgenperf) {
 177                                 bestgenperf = perf;
 178                                 best = *algo;
 179                         }
 180                         pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
 181                                 (perf * HZ * (disks-2)) >>
 182                                 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
 183
 184                         if (!(*algo)->xor_syndrome)
 185                                 continue;
 186
 187                         perf = 0;
 188
 189                         preempt_disable();
 190                         j0 = jiffies;
 191                         while ((j1 = jiffies) == j0)
 192                                 cpu_relax();
 193                         while (time_before(jiffies,
 194                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 195                                 (*algo)->xor_syndrome(disks, start, stop,
 196                                                       PAGE_SIZE, *dptrs);
 197                                 perf++;
 198                         }
 199                         preempt_enable();
 200
 201                         if (best == *algo)
 202                                 bestxorperf = perf;
 203
 204                         pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
 205                                 (perf * HZ * (disks-2)) >>
 206                                 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
 207                 }
 208         }
 209
 210         if (best) {
 211                 if (IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
 212                         pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
 213                                 best->name,
 214                                 (bestgenperf * HZ * (disks-2)) >>
 215                                 (20 - PAGE_SHIFT+RAID6_TIME_JIFFIES_LG2));
 216                         if (best->xor_syndrome)
 217                                 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
 218                                         (bestxorperf * HZ * (disks-2)) >>
 219                                         (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
 220                 } else
 221                         pr_info("raid6: skip pq benchmark and using algorithm %s\n",
 222                                 best->name);
 223                 raid6_call = *best;
 224         } else
 225                 pr_err("raid6: Yikes!  No algorithm found!\n");
 226
 227         return best;
 228 }
 229
 230
 231 /* Try to pick the best algorithm */
 232 /* This code uses the gfmul table as convenient data set to abuse */
 233
 234 int __init raid6_select_algo(void)
 235 {
 236         const int disks = RAID6_TEST_DISKS;
 237
 238         const struct raid6_calls *gen_best;
 239         const struct raid6_recov_calls *rec_best;
 240         char *disk_ptr, *p;
 241         void *dptrs[RAID6_TEST_DISKS];
 242         int i, cycle;
 243
 244         /* prepare the buffer and fill it circularly with gfmul table */
 245         disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
 246         if (!disk_ptr) {
 247                 pr_err("raid6: Yikes!  No memory available.\n");
 248                 return -ENOMEM;
 249         }
 250
 251         p = disk_ptr;
 252         for (i = 0; i < disks; i++)
 253                 dptrs[i] = p + PAGE_SIZE * i;
 254
 255         cycle = ((disks - 2) * PAGE_SIZE) / 65536;
 256         for (i = 0; i < cycle; i++) {
 257                 memcpy(p, raid6_gfmul, 65536);
 258                 p += 65536;
 259         }
 260
 261         if ((disks - 2) * PAGE_SIZE % 65536)
 262                 memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
 263
 264         /* select raid gen_syndrome function */
 265         gen_best = raid6_choose_gen(&dptrs, disks);
 266
 267         /* select raid recover functions */
 268         rec_best = raid6_choose_recov();
 269
 270         free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
 271
 272         return gen_best && rec_best ? 0 : -EINVAL;
 273 }
 274
 275 static void raid6_exit(void)
 276 {
 277         do { } while (0);
 278 }
 279
 280 subsys_initcall(raid6_select_algo);
 281 module_exit(raid6_exit);
 282 MODULE_LICENSE("GPL");
 283 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");