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         &raid6_recov_intx1,
 117         NULL
 118 };
 119
 120 #ifdef __KERNEL__
 121 #define RAID6_TIME_JIFFIES_LG2  4
 122 #else
 123 /* Need more time to be stable in userspace */
 124 #define RAID6_TIME_JIFFIES_LG2  9
 125 #define time_before(x, y) ((x) < (y))
 126 #endif
 127
 128 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
 129 {
 130         const struct raid6_recov_calls *const *algo;
 131         const struct raid6_recov_calls *best;
 132
 133         for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
 134                 if (!best || (*algo)->priority > best->priority)
 135                         if (!(*algo)->valid || (*algo)->valid())
 136                                 best = *algo;
 137
 138         if (best) {
 139                 raid6_2data_recov = best->data2;
 140                 raid6_datap_recov = best->datap;
 141
 142                 pr_info("raid6: using %s recovery algorithm\n", best->name);
 143         } else
 144                 pr_err("raid6: Yikes! No recovery algorithm found!\n");
 145
 146         return best;
 147 }
 148
 149 static inline const struct raid6_calls *raid6_choose_gen(
 150         void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
 151 {
 152         unsigned long perf, bestgenperf, bestxorperf, j0, j1;
 153         int start = (disks>>1)-1, stop = disks-3;       /* work on the second half of the disks */
 154         const struct raid6_calls *const *algo;
 155         const struct raid6_calls *best;
 156
 157         for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
 158                 if (!best || (*algo)->prefer >= best->prefer) {
 159                         if ((*algo)->valid && !(*algo)->valid())
 160                                 continue;
 161
 162                         perf = 0;
 163
 164                         preempt_disable();
 165                         j0 = jiffies;
 166                         while ((j1 = jiffies) == j0)
 167                                 cpu_relax();
 168                         while (time_before(jiffies,
 169                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 170                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
 171                                 perf++;
 172                         }
 173                         preempt_enable();
 174
 175                         if (perf > bestgenperf) {
 176                                 bestgenperf = perf;
 177                                 best = *algo;
 178                         }
 179                         pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
 180                                (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 181
 182                         if (!(*algo)->xor_syndrome)
 183                                 continue;
 184
 185                         perf = 0;
 186
 187                         preempt_disable();
 188                         j0 = jiffies;
 189                         while ((j1 = jiffies) == j0)
 190                                 cpu_relax();
 191                         while (time_before(jiffies,
 192                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 193                                 (*algo)->xor_syndrome(disks, start, stop,
 194                                                       PAGE_SIZE, *dptrs);
 195                                 perf++;
 196                         }
 197                         preempt_enable();
 198
 199                         if (best == *algo)
 200                                 bestxorperf = perf;
 201
 202                         pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
 203                                 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
 204                 }
 205         }
 206
 207         if (best) {
 208                 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
 209                        best->name,
 210                        (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 211                 if (best->xor_syndrome)
 212                         pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
 213                                (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
 214                 raid6_call = *best;
 215         } else
 216                 pr_err("raid6: Yikes!  No algorithm found!\n");
 217
 218         return best;
 219 }
 220
 221
 222 /* Try to pick the best algorithm */
 223 /* This code uses the gfmul table as convenient data set to abuse */
 224
 225 int __init raid6_select_algo(void)
 226 {
 227         const int disks = (65536/PAGE_SIZE)+2;
 228
 229         const struct raid6_calls *gen_best;
 230         const struct raid6_recov_calls *rec_best;
 231         char *syndromes;
 232         void *dptrs[(65536/PAGE_SIZE)+2];
 233         int i;
 234
 235         for (i = 0; i < disks-2; i++)
 236                 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
 237
 238         /* Normal code - use a 2-page allocation to avoid D$ conflict */
 239         syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
 240
 241         if (!syndromes) {
 242                 pr_err("raid6: Yikes!  No memory available.\n");
 243                 return -ENOMEM;
 244         }
 245
 246         dptrs[disks-2] = syndromes;
 247         dptrs[disks-1] = syndromes + PAGE_SIZE;
 248
 249         /* select raid gen_syndrome function */
 250         gen_best = raid6_choose_gen(&dptrs, disks);
 251
 252         /* select raid recover functions */
 253         rec_best = raid6_choose_recov();
 254
 255         free_pages((unsigned long)syndromes, 1);
 256
 257         return gen_best && rec_best ? 0 : -EINVAL;
 258 }
 259
 260 static void raid6_exit(void)
 261 {
 262         do { } while (0);
 263 }
 264
 265 subsys_initcall(raid6_select_algo);
 266 module_exit(raid6_exit);
 267 MODULE_LICENSE("GPL");
 268 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");