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         &raid6_intx1,
  70         &raid6_intx2,
  71         &raid6_intx4,
  72         &raid6_intx8,
  73         NULL
  74 };
  75
  76 void (*raid6_2data_recov)(int, size_t, int, int, void **);
  77 EXPORT_SYMBOL_GPL(raid6_2data_recov);
  78
  79 void (*raid6_datap_recov)(int, size_t, int, void **);
  80 EXPORT_SYMBOL_GPL(raid6_datap_recov);
  81
  82 const struct raid6_recov_calls *const raid6_recov_algos[] = {
  83 #if (defined(__i386__) || defined(__x86_64__)) && !defined(__arch_um__)
  84 #ifdef CONFIG_AS_AVX2
  85         &raid6_recov_avx2,
  86 #endif
  87         &raid6_recov_ssse3,
  88 #endif
  89         &raid6_recov_intx1,
  90         NULL
  91 };
  92
  93 #ifdef __KERNEL__
  94 #define RAID6_TIME_JIFFIES_LG2  4
  95 #else
  96 /* Need more time to be stable in userspace */
  97 #define RAID6_TIME_JIFFIES_LG2  9
  98 #define time_before(x, y) ((x) < (y))
  99 #endif
 100
 101 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
 102 {
 103         const struct raid6_recov_calls *const *algo;
 104         const struct raid6_recov_calls *best;
 105
 106         for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
 107                 if (!best || (*algo)->priority > best->priority)
 108                         if (!(*algo)->valid || (*algo)->valid())
 109                                 best = *algo;
 110
 111         if (best) {
 112                 raid6_2data_recov = best->data2;
 113                 raid6_datap_recov = best->datap;
 114
 115                 printk("raid6: using %s recovery algorithm\n", best->name);
 116         } else
 117                 printk("raid6: Yikes! No recovery algorithm found!\n");
 118
 119         return best;
 120 }
 121
 122 static inline const struct raid6_calls *raid6_choose_gen(
 123         void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
 124 {
 125         unsigned long perf, bestperf, j0, j1;
 126         const struct raid6_calls *const *algo;
 127         const struct raid6_calls *best;
 128
 129         for (bestperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
 130                 if (!best || (*algo)->prefer >= best->prefer) {
 131                         if ((*algo)->valid && !(*algo)->valid())
 132                                 continue;
 133
 134                         perf = 0;
 135
 136                         preempt_disable();
 137                         j0 = jiffies;
 138                         while ((j1 = jiffies) == j0)
 139                                 cpu_relax();
 140                         while (time_before(jiffies,
 141                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 142                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
 143                                 perf++;
 144                         }
 145                         preempt_enable();
 146
 147                         if (perf > bestperf) {
 148                                 bestperf = perf;
 149                                 best = *algo;
 150                         }
 151                         printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
 152                                (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 153                 }
 154         }
 155
 156         if (best) {
 157                 printk("raid6: using algorithm %s (%ld MB/s)\n",
 158                        best->name,
 159                        (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 160                 raid6_call = *best;
 161         } else
 162                 printk("raid6: Yikes!  No algorithm found!\n");
 163
 164         return best;
 165 }
 166
 167
 168 /* Try to pick the best algorithm */
 169 /* This code uses the gfmul table as convenient data set to abuse */
 170
 171 int __init raid6_select_algo(void)
 172 {
 173         const int disks = (65536/PAGE_SIZE)+2;
 174
 175         const struct raid6_calls *gen_best;
 176         const struct raid6_recov_calls *rec_best;
 177         char *syndromes;
 178         void *dptrs[(65536/PAGE_SIZE)+2];
 179         int i;
 180
 181         for (i = 0; i < disks-2; i++)
 182                 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
 183
 184         /* Normal code - use a 2-page allocation to avoid D$ conflict */
 185         syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
 186
 187         if (!syndromes) {
 188                 printk("raid6: Yikes!  No memory available.\n");
 189                 return -ENOMEM;
 190         }
 191
 192         dptrs[disks-2] = syndromes;
 193         dptrs[disks-1] = syndromes + PAGE_SIZE;
 194
 195         /* select raid gen_syndrome function */
 196         gen_best = raid6_choose_gen(&dptrs, disks);
 197
 198         /* select raid recover functions */
 199         rec_best = raid6_choose_recov();
 200
 201         free_pages((unsigned long)syndromes, 1);
 202
 203         return gen_best && rec_best ? 0 : -EINVAL;
 204 }
 205
 206 static void raid6_exit(void)
 207 {
 208         do { } while (0);
 209 }
 210
 211 subsys_initcall(raid6_select_algo);
 212 module_exit(raid6_exit);
 213 MODULE_LICENSE("GPL");
 214 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");