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         &raid6_intx1,
  82         &raid6_intx2,
  83         &raid6_intx4,
  84         &raid6_intx8,
  85 #ifdef CONFIG_KERNEL_MODE_NEON
  86         &raid6_neonx1,
  87         &raid6_neonx2,
  88         &raid6_neonx4,
  89         &raid6_neonx8,
  90 #endif
  91         NULL
  92 };
  93
  94 void (*raid6_2data_recov)(int, size_t, int, int, void **);
  95 EXPORT_SYMBOL_GPL(raid6_2data_recov);
  96
  97 void (*raid6_datap_recov)(int, size_t, int, void **);
  98 EXPORT_SYMBOL_GPL(raid6_datap_recov);
  99
 100 const struct raid6_recov_calls *const raid6_recov_algos[] = {
 101 #ifdef CONFIG_AS_AVX512
 102         &raid6_recov_avx512,
 103 #endif
 104 #ifdef CONFIG_AS_AVX2
 105         &raid6_recov_avx2,
 106 #endif
 107 #ifdef CONFIG_AS_SSSE3
 108         &raid6_recov_ssse3,
 109 #endif
 110         &raid6_recov_intx1,
 111         NULL
 112 };
 113
 114 #ifdef __KERNEL__
 115 #define RAID6_TIME_JIFFIES_LG2  4
 116 #else
 117 /* Need more time to be stable in userspace */
 118 #define RAID6_TIME_JIFFIES_LG2  9
 119 #define time_before(x, y) ((x) < (y))
 120 #endif
 121
 122 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
 123 {
 124         const struct raid6_recov_calls *const *algo;
 125         const struct raid6_recov_calls *best;
 126
 127         for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
 128                 if (!best || (*algo)->priority > best->priority)
 129                         if (!(*algo)->valid || (*algo)->valid())
 130                                 best = *algo;
 131
 132         if (best) {
 133                 raid6_2data_recov = best->data2;
 134                 raid6_datap_recov = best->datap;
 135
 136                 pr_info("raid6: using %s recovery algorithm\n", best->name);
 137         } else
 138                 pr_err("raid6: Yikes! No recovery algorithm found!\n");
 139
 140         return best;
 141 }
 142
 143 static inline const struct raid6_calls *raid6_choose_gen(
 144         void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
 145 {
 146         unsigned long perf, bestgenperf, bestxorperf, j0, j1;
 147         int start = (disks>>1)-1, stop = disks-3;       /* work on the second half of the disks */
 148         const struct raid6_calls *const *algo;
 149         const struct raid6_calls *best;
 150
 151         for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
 152                 if (!best || (*algo)->prefer >= best->prefer) {
 153                         if ((*algo)->valid && !(*algo)->valid())
 154                                 continue;
 155
 156                         perf = 0;
 157
 158                         preempt_disable();
 159                         j0 = jiffies;
 160                         while ((j1 = jiffies) == j0)
 161                                 cpu_relax();
 162                         while (time_before(jiffies,
 163                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 164                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
 165                                 perf++;
 166                         }
 167                         preempt_enable();
 168
 169                         if (perf > bestgenperf) {
 170                                 bestgenperf = perf;
 171                                 best = *algo;
 172                         }
 173                         pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
 174                                (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 175
 176                         if (!(*algo)->xor_syndrome)
 177                                 continue;
 178
 179                         perf = 0;
 180
 181                         preempt_disable();
 182                         j0 = jiffies;
 183                         while ((j1 = jiffies) == j0)
 184                                 cpu_relax();
 185                         while (time_before(jiffies,
 186                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 187                                 (*algo)->xor_syndrome(disks, start, stop,
 188                                                       PAGE_SIZE, *dptrs);
 189                                 perf++;
 190                         }
 191                         preempt_enable();
 192
 193                         if (best == *algo)
 194                                 bestxorperf = perf;
 195
 196                         pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
 197                                 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
 198                 }
 199         }
 200
 201         if (best) {
 202                 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
 203                        best->name,
 204                        (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 205                 if (best->xor_syndrome)
 206                         pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
 207                                (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
 208                 raid6_call = *best;
 209         } else
 210                 pr_err("raid6: Yikes!  No algorithm found!\n");
 211
 212         return best;
 213 }
 214
 215
 216 /* Try to pick the best algorithm */
 217 /* This code uses the gfmul table as convenient data set to abuse */
 218
 219 int __init raid6_select_algo(void)
 220 {
 221         const int disks = (65536/PAGE_SIZE)+2;
 222
 223         const struct raid6_calls *gen_best;
 224         const struct raid6_recov_calls *rec_best;
 225         char *syndromes;
 226         void *dptrs[(65536/PAGE_SIZE)+2];
 227         int i;
 228
 229         for (i = 0; i < disks-2; i++)
 230                 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
 231
 232         /* Normal code - use a 2-page allocation to avoid D$ conflict */
 233         syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
 234
 235         if (!syndromes) {
 236                 pr_err("raid6: Yikes!  No memory available.\n");
 237                 return -ENOMEM;
 238         }
 239
 240         dptrs[disks-2] = syndromes;
 241         dptrs[disks-1] = syndromes + PAGE_SIZE;
 242
 243         /* select raid gen_syndrome function */
 244         gen_best = raid6_choose_gen(&dptrs, disks);
 245
 246         /* select raid recover functions */
 247         rec_best = raid6_choose_recov();
 248
 249         free_pages((unsigned long)syndromes, 1);
 250
 251         return gen_best && rec_best ? 0 : -EINVAL;
 252 }
 253
 254 static void raid6_exit(void)
 255 {
 256         do { } while (0);
 257 }
 258
 259 subsys_initcall(raid6_select_algo);
 260 module_exit(raid6_exit);
 261 MODULE_LICENSE("GPL");
 262 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");