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