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(__ia64__)
  38         &raid6_intx16,
  39         &raid6_intx32,
  40 #endif
  41 #if defined(__i386__) && !defined(__arch_um__)
  42         &raid6_mmxx1,
  43         &raid6_mmxx2,
  44         &raid6_sse1x1,
  45         &raid6_sse1x2,
  46         &raid6_sse2x1,
  47         &raid6_sse2x2,
  48 #ifdef CONFIG_AS_AVX2
  49         &raid6_avx2x1,
  50         &raid6_avx2x2,
  51 #endif
  52 #ifdef CONFIG_AS_AVX512
  53         &raid6_avx512x1,
  54         &raid6_avx512x2,
  55 #endif
  56 #endif
  57 #if defined(__x86_64__) && !defined(__arch_um__)
  58         &raid6_sse2x1,
  59         &raid6_sse2x2,
  60         &raid6_sse2x4,
  61 #ifdef CONFIG_AS_AVX2
  62         &raid6_avx2x1,
  63         &raid6_avx2x2,
  64         &raid6_avx2x4,
  65 #endif
  66 #ifdef CONFIG_AS_AVX512
  67         &raid6_avx512x1,
  68         &raid6_avx512x2,
  69         &raid6_avx512x4,
  70 #endif
  71 #endif
  72 #ifdef CONFIG_ALTIVEC
  73         &raid6_altivec1,
  74         &raid6_altivec2,
  75         &raid6_altivec4,
  76         &raid6_altivec8,
  77 #endif
  78 #if defined(CONFIG_TILEGX)
  79         &raid6_tilegx8,
  80 #endif
  81 #if defined(CONFIG_S390)
  82         &raid6_s390vx8,
  83 #endif
  84         &raid6_intx1,
  85         &raid6_intx2,
  86         &raid6_intx4,
  87         &raid6_intx8,
  88 #ifdef CONFIG_KERNEL_MODE_NEON
  89         &raid6_neonx1,
  90         &raid6_neonx2,
  91         &raid6_neonx4,
  92         &raid6_neonx8,
  93 #endif
  94         NULL
  95 };
  96
  97 void (*raid6_2data_recov)(int, size_t, int, int, void **);
  98 EXPORT_SYMBOL_GPL(raid6_2data_recov);
  99
 100 void (*raid6_datap_recov)(int, size_t, int, void **);
 101 EXPORT_SYMBOL_GPL(raid6_datap_recov);
 102
 103 const struct raid6_recov_calls *const raid6_recov_algos[] = {
 104 #ifdef CONFIG_AS_AVX512
 105         &raid6_recov_avx512,
 106 #endif
 107 #ifdef CONFIG_AS_AVX2
 108         &raid6_recov_avx2,
 109 #endif
 110 #ifdef CONFIG_AS_SSSE3
 111         &raid6_recov_ssse3,
 112 #endif
 113 #ifdef CONFIG_S390
 114         &raid6_recov_s390xc,
 115 #endif
 116 #if defined(CONFIG_KERNEL_MODE_NEON)
 117         &raid6_recov_neon,
 118 #endif
 119         &raid6_recov_intx1,
 120         NULL
 121 };
 122
 123 #ifdef __KERNEL__
 124 #define RAID6_TIME_JIFFIES_LG2  4
 125 #else
 126 /* Need more time to be stable in userspace */
 127 #define RAID6_TIME_JIFFIES_LG2  9
 128 #define time_before(x, y) ((x) < (y))
 129 #endif
 130
 131 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
 132 {
 133         const struct raid6_recov_calls *const *algo;
 134         const struct raid6_recov_calls *best;
 135
 136         for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
 137                 if (!best || (*algo)->priority > best->priority)
 138                         if (!(*algo)->valid || (*algo)->valid())
 139                                 best = *algo;
 140
 141         if (best) {
 142                 raid6_2data_recov = best->data2;
 143                 raid6_datap_recov = best->datap;
 144
 145                 pr_info("raid6: using %s recovery algorithm\n", best->name);
 146         } else
 147                 pr_err("raid6: Yikes! No recovery algorithm found!\n");
 148
 149         return best;
 150 }
 151
 152 static inline const struct raid6_calls *raid6_choose_gen(
 153         void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
 154 {
 155         unsigned long perf, bestgenperf, bestxorperf, j0, j1;
 156         int start = (disks>>1)-1, stop = disks-3;       /* work on the second half of the disks */
 157         const struct raid6_calls *const *algo;
 158         const struct raid6_calls *best;
 159
 160         for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
 161                 if (!best || (*algo)->prefer >= best->prefer) {
 162                         /* 2 ^ (RAID6_TIME_JIFFIES_LG2 - 0.5) */
 163                         const unsigned long raid6_time_jiffies =
 164                                 ((1 << RAID6_TIME_JIFFIES_LG2) * 181) >> 8;
 165
 166                         if ((*algo)->valid && !(*algo)->valid())
 167                                 continue;
 168
 169                         perf = 0;
 170
 171                         preempt_disable();
 172                         j0 = jiffies;
 173                         while ((j1 = jiffies) == j0)
 174                                 cpu_relax();
 175                         while (time_before(jiffies,
 176                                             j1 + raid6_time_jiffies)) {
 177                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
 178                                 perf++;
 179                         }
 180                         preempt_enable();
 181
 182                         if (perf > bestgenperf) {
 183                                 bestgenperf = perf;
 184                                 best = *algo;
 185                         }
 186                         pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
 187                                (((perf*HZ) >>
 188                                 (20-16+RAID6_TIME_JIFFIES_LG2)) * 1448) >> 10);
 189
 190                         if (!(*algo)->xor_syndrome)
 191                                 continue;
 192
 193                         perf = 0;
 194
 195                         preempt_disable();
 196                         j0 = jiffies;
 197                         while ((j1 = jiffies) == j0)
 198                                 cpu_relax();
 199                         while (time_before(jiffies,
 200                                             j1 + raid6_time_jiffies)) {
 201                                 (*algo)->xor_syndrome(disks, start, stop,
 202                                                       PAGE_SIZE, *dptrs);
 203                                 perf++;
 204                         }
 205                         preempt_enable();
 206
 207                         if (best == *algo)
 208                                 bestxorperf = perf;
 209
 210                         pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
 211                                 (((perf*HZ) >>
 212                                  (20-16+RAID6_TIME_JIFFIES_LG2+1)) * 1448) >> 10);
 213                 }
 214         }
 215
 216         if (best) {
 217                 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
 218                        best->name,
 219                        (((bestgenperf*HZ) >>
 220                         (20-16+RAID6_TIME_JIFFIES_LG2)) * 1448) >> 10);
 221                 if (best->xor_syndrome)
 222                         pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
 223                                (((bestxorperf*HZ) >>
 224                                 (20-16+RAID6_TIME_JIFFIES_LG2+1)) * 1448) >> 10);
 225                 raid6_call = *best;
 226         } else
 227                 pr_err("raid6: Yikes!  No algorithm found!\n");
 228
 229         return best;
 230 }
 231
 232
 233 /* Try to pick the best algorithm */
 234 /* This code uses the gfmul table as convenient data set to abuse */
 235
 236 int __init raid6_select_algo(void)
 237 {
 238         const int disks = (65536/PAGE_SIZE)+2;
 239
 240         const struct raid6_calls *gen_best;
 241         const struct raid6_recov_calls *rec_best;
 242         char *syndromes;
 243         void *dptrs[(65536/PAGE_SIZE)+2];
 244         int i;
 245
 246         for (i = 0; i < disks-2; i++)
 247                 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
 248
 249         /* Normal code - use a 2-page allocation to avoid D$ conflict */
 250         syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
 251
 252         if (!syndromes) {
 253                 pr_err("raid6: Yikes!  No memory available.\n");
 254                 return -ENOMEM;
 255         }
 256
 257         dptrs[disks-2] = syndromes;
 258         dptrs[disks-1] = syndromes + PAGE_SIZE;
 259
 260         /* select raid gen_syndrome function */
 261         gen_best = raid6_choose_gen(&dptrs, disks);
 262
 263         /* select raid recover functions */
 264         rec_best = raid6_choose_recov();
 265
 266         free_pages((unsigned long)syndromes, 1);
 267
 268         return gen_best && rec_best ? 0 : -EINVAL;
 269 }
 270
 271 static void raid6_exit(void)
 272 {
 273         do { } while (0);
 274 }
 275
 276 subsys_initcall(raid6_select_algo);
 277 module_exit(raid6_exit);
 278 MODULE_LICENSE("GPL");
 279 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");