lib/raid6/algos.c

   1 /* -*- linux-c -*- ------------------------------------------------------- *
   2  *
   3  *   Copyright 2002 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * raid6/algos.c
  15  *
  16  * Algorithm list and algorithm selection for RAID-6
  17  */
  18
  19 #include <linux/raid/pq.h>
  20 #ifndef __KERNEL__
  21 #include <sys/mman.h>
  22 #include <stdio.h>
  23 #else
  24 #include <linux/module.h>
  25 #include <linux/gfp.h>
  26 #if !RAID6_USE_EMPTY_ZERO_PAGE
  27 /* In .bss so it's zeroed */
  28 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
  29 EXPORT_SYMBOL(raid6_empty_zero_page);
  30 #endif
  31 #endif
  32
  33 struct raid6_calls raid6_call;
  34 EXPORT_SYMBOL_GPL(raid6_call);
  35
  36 const struct raid6_calls * const raid6_algos[] = {
  37 #if defined(__i386__) && !defined(__arch_um__)
  38 #ifdef CONFIG_AS_AVX512
  39         &raid6_avx512x2,
  40         &raid6_avx512x1,
  41 #endif
  42 #ifdef CONFIG_AS_AVX2
  43         &raid6_avx2x2,
  44         &raid6_avx2x1,
  45 #endif
  46         &raid6_sse2x2,
  47         &raid6_sse2x1,
  48         &raid6_sse1x2,
  49         &raid6_sse1x1,
  50         &raid6_mmxx2,
  51         &raid6_mmxx1,
  52 #endif
  53 #if defined(__x86_64__) && !defined(__arch_um__)
  54 #ifdef CONFIG_AS_AVX512
  55         &raid6_avx512x4,
  56         &raid6_avx512x2,
  57         &raid6_avx512x1,
  58 #endif
  59 #ifdef CONFIG_AS_AVX2
  60         &raid6_avx2x4,
  61         &raid6_avx2x2,
  62         &raid6_avx2x1,
  63 #endif
  64         &raid6_sse2x4,
  65         &raid6_sse2x2,
  66         &raid6_sse2x1,
  67 #endif
  68 #ifdef CONFIG_ALTIVEC
  69         &raid6_vpermxor8,
  70         &raid6_vpermxor4,
  71         &raid6_vpermxor2,
  72         &raid6_vpermxor1,
  73         &raid6_altivec8,
  74         &raid6_altivec4,
  75         &raid6_altivec2,
  76         &raid6_altivec1,
  77 #endif
  78 #if defined(CONFIG_S390)
  79         &raid6_s390vx8,
  80 #endif
  81 #ifdef CONFIG_KERNEL_MODE_NEON
  82         &raid6_neonx8,
  83         &raid6_neonx4,
  84         &raid6_neonx2,
  85         &raid6_neonx1,
  86 #endif
  87 #if defined(__ia64__)
  88         &raid6_intx32,
  89         &raid6_intx16,
  90 #endif
  91         &raid6_intx8,
  92         &raid6_intx4,
  93         &raid6_intx2,
  94         &raid6_intx1,
  95         NULL
  96 };
  97
  98 void (*raid6_2data_recov)(int, size_t, int, int, void **);
  99 EXPORT_SYMBOL_GPL(raid6_2data_recov);
 100
 101 void (*raid6_datap_recov)(int, size_t, int, void **);
 102 EXPORT_SYMBOL_GPL(raid6_datap_recov);
 103
 104 const struct raid6_recov_calls *const raid6_recov_algos[] = {
 105 #ifdef CONFIG_AS_AVX512
 106         &raid6_recov_avx512,
 107 #endif
 108 #ifdef CONFIG_AS_AVX2
 109         &raid6_recov_avx2,
 110 #endif
 111 #ifdef CONFIG_AS_SSSE3
 112         &raid6_recov_ssse3,
 113 #endif
 114 #ifdef CONFIG_S390
 115         &raid6_recov_s390xc,
 116 #endif
 117 #if defined(CONFIG_KERNEL_MODE_NEON)
 118         &raid6_recov_neon,
 119 #endif
 120         &raid6_recov_intx1,
 121         NULL
 122 };
 123
 124 #ifdef __KERNEL__
 125 #define RAID6_TIME_JIFFIES_LG2  4
 126 #else
 127 /* Need more time to be stable in userspace */
 128 #define RAID6_TIME_JIFFIES_LG2  9
 129 #define time_before(x, y) ((x) < (y))
 130 #endif
 131
 132 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
 133 {
 134         const struct raid6_recov_calls *const *algo;
 135         const struct raid6_recov_calls *best;
 136
 137         for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
 138                 if (!best || (*algo)->priority > best->priority)
 139                         if (!(*algo)->valid || (*algo)->valid())
 140                                 best = *algo;
 141
 142         if (best) {
 143                 raid6_2data_recov = best->data2;
 144                 raid6_datap_recov = best->datap;
 145
 146                 pr_info("raid6: using %s recovery algorithm\n", best->name);
 147         } else
 148                 pr_err("raid6: Yikes! No recovery algorithm found!\n");
 149
 150         return best;
 151 }
 152
 153 static inline const struct raid6_calls *raid6_choose_gen(
 154         void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
 155 {
 156         unsigned long perf, bestgenperf, bestxorperf, j0, j1;
 157         int start = (disks>>1)-1, stop = disks-3;       /* work on the second half of the disks */
 158         const struct raid6_calls *const *algo;
 159         const struct raid6_calls *best;
 160
 161         for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
 162                 if (!best || (*algo)->prefer >= best->prefer) {
 163                         if ((*algo)->valid && !(*algo)->valid())
 164                                 continue;
 165
 166                         if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
 167                                 best = *algo;
 168                                 break;
 169                         }
 170
 171                         perf = 0;
 172
 173                         preempt_disable();
 174                         j0 = jiffies;
 175                         while ((j1 = jiffies) == j0)
 176                                 cpu_relax();
 177                         while (time_before(jiffies,
 178                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 179                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
 180                                 perf++;
 181                         }
 182                         preempt_enable();
 183
 184                         if (perf > bestgenperf) {
 185                                 bestgenperf = perf;
 186                                 best = *algo;
 187                         }
 188                         pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
 189                                (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 190
 191                         if (!(*algo)->xor_syndrome)
 192                                 continue;
 193
 194                         perf = 0;
 195
 196                         preempt_disable();
 197                         j0 = jiffies;
 198                         while ((j1 = jiffies) == j0)
 199                                 cpu_relax();
 200                         while (time_before(jiffies,
 201                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 202                                 (*algo)->xor_syndrome(disks, start, stop,
 203                                                       PAGE_SIZE, *dptrs);
 204                                 perf++;
 205                         }
 206                         preempt_enable();
 207
 208                         if (best == *algo)
 209                                 bestxorperf = perf;
 210
 211                         pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
 212                                 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
 213                 }
 214         }
 215
 216         if (best) {
 217                 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
 218                        best->name,
 219                        (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 220                 if (best->xor_syndrome)
 221                         pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
 222                                (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
 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 = (65536/PAGE_SIZE)+2;
 237
 238         const struct raid6_calls *gen_best;
 239         const struct raid6_recov_calls *rec_best;
 240         char *syndromes;
 241         void *dptrs[(65536/PAGE_SIZE)+2];
 242         int i;
 243
 244         for (i = 0; i < disks-2; i++)
 245                 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
 246
 247         /* Normal code - use a 2-page allocation to avoid D$ conflict */
 248         syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
 249
 250         if (!syndromes) {
 251                 pr_err("raid6: Yikes!  No memory available.\n");
 252                 return -ENOMEM;
 253         }
 254
 255         dptrs[disks-2] = syndromes;
 256         dptrs[disks-1] = syndromes + PAGE_SIZE;
 257
 258         /* select raid gen_syndrome function */
 259         gen_best = raid6_choose_gen(&dptrs, disks);
 260
 261         /* select raid recover functions */
 262         rec_best = raid6_choose_recov();
 263
 264         free_pages((unsigned long)syndromes, 1);
 265
 266         return gen_best && rec_best ? 0 : -EINVAL;
 267 }
 268
 269 static void raid6_exit(void)
 270 {
 271         do { } while (0);
 272 }
 273
 274 subsys_initcall(raid6_select_algo);
 275 module_exit(raid6_exit);
 276 MODULE_LICENSE("GPL");
 277 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");