drivers/md/raid6algos.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  *   Bostom 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  * raid6algos.c
  15  *
  16  * Algorithm list and algorithm selection for RAID-6
  17  */
  18
  19 #include "raid6.h"
  20 #ifndef __KERNEL__
  21 #include <sys/mman.h>
  22 #endif
  23
  24 struct raid6_calls raid6_call;
  25
  26 /* Various routine sets */
  27 extern const struct raid6_calls raid6_intx1;
  28 extern const struct raid6_calls raid6_intx2;
  29 extern const struct raid6_calls raid6_intx4;
  30 extern const struct raid6_calls raid6_intx8;
  31 extern const struct raid6_calls raid6_intx16;
  32 extern const struct raid6_calls raid6_intx32;
  33 extern const struct raid6_calls raid6_mmxx1;
  34 extern const struct raid6_calls raid6_mmxx2;
  35 extern const struct raid6_calls raid6_sse1x1;
  36 extern const struct raid6_calls raid6_sse1x2;
  37 extern const struct raid6_calls raid6_sse2x1;
  38 extern const struct raid6_calls raid6_sse2x2;
  39 extern const struct raid6_calls raid6_sse2x4;
  40 extern const struct raid6_calls raid6_altivec1;
  41 extern const struct raid6_calls raid6_altivec2;
  42 extern const struct raid6_calls raid6_altivec4;
  43 extern const struct raid6_calls raid6_altivec8;
  44
  45 const struct raid6_calls * const raid6_algos[] = {
  46         &raid6_intx1,
  47         &raid6_intx2,
  48         &raid6_intx4,
  49         &raid6_intx8,
  50 #if defined(__ia64__)
  51         &raid6_intx16,
  52         &raid6_intx32,
  53 #endif
  54 #if defined(__i386__)
  55         &raid6_mmxx1,
  56         &raid6_mmxx2,
  57         &raid6_sse1x1,
  58         &raid6_sse1x2,
  59         &raid6_sse2x1,
  60         &raid6_sse2x2,
  61 #endif
  62 #if defined(__x86_64__)
  63         &raid6_sse2x1,
  64         &raid6_sse2x2,
  65         &raid6_sse2x4,
  66 #endif
  67 #ifdef CONFIG_ALTIVEC
  68         &raid6_altivec1,
  69         &raid6_altivec2,
  70         &raid6_altivec4,
  71         &raid6_altivec8,
  72 #endif
  73         NULL
  74 };
  75
  76 #ifdef __KERNEL__
  77 #define RAID6_TIME_JIFFIES_LG2  4
  78 #else
  79 /* Need more time to be stable in userspace */
  80 #define RAID6_TIME_JIFFIES_LG2  9
  81 #endif
  82
  83 /* Try to pick the best algorithm */
  84 /* This code uses the gfmul table as convenient data set to abuse */
  85
  86 int __init raid6_select_algo(void)
  87 {
  88         const struct raid6_calls * const * algo;
  89         const struct raid6_calls * best;
  90         char *syndromes;
  91         void *dptrs[(65536/PAGE_SIZE)+2];
  92         int i, disks;
  93         unsigned long perf, bestperf;
  94         int bestprefer;
  95         unsigned long j0, j1;
  96
  97         disks = (65536/PAGE_SIZE)+2;
  98         for ( i = 0 ; i < disks-2 ; i++ ) {
  99                 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
 100         }
 101
 102         /* Normal code - use a 2-page allocation to avoid D$ conflict */
 103         syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
 104
 105         if ( !syndromes ) {
 106                 printk("raid6: Yikes!  No memory available.\n");
 107                 return -ENOMEM;
 108         }
 109
 110         dptrs[disks-2] = syndromes;
 111         dptrs[disks-1] = syndromes + PAGE_SIZE;
 112
 113         bestperf = 0;  bestprefer = 0;  best = NULL;
 114
 115         for ( algo = raid6_algos ; *algo ; algo++ ) {
 116                 if ( !(*algo)->valid || (*algo)->valid() ) {
 117                         perf = 0;
 118
 119                         preempt_disable();
 120                         j0 = jiffies;
 121                         while ( (j1 = jiffies) == j0 )
 122                                 cpu_relax();
 123                         while ( (jiffies-j1) < (1 << RAID6_TIME_JIFFIES_LG2) ) {
 124                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
 125                                 perf++;
 126                         }
 127                         preempt_enable();
 128
 129                         if ( (*algo)->prefer > bestprefer ||
 130                              ((*algo)->prefer == bestprefer &&
 131                               perf > bestperf) ) {
 132                                 best = *algo;
 133                                 bestprefer = best->prefer;
 134                                 bestperf = perf;
 135                         }
 136                         printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
 137                                (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 138                 }
 139         }
 140
 141         if ( best )
 142                 printk("raid6: using algorithm %s (%ld MB/s)\n",
 143                        best->name,
 144                        (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 145         else
 146                 printk("raid6: Yikes!  No algorithm found!\n");
 147
 148         raid6_call = *best;
 149
 150         free_pages((unsigned long)syndromes, 1);
 151
 152         return best ? 0 : -EINVAL;
 153 }