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 #include <stdio.h>
  23 #endif
  24
  25 struct raid6_calls raid6_call;
  26
  27 /* Various routine sets */
  28 extern const struct raid6_calls raid6_intx1;
  29 extern const struct raid6_calls raid6_intx2;
  30 extern const struct raid6_calls raid6_intx4;
  31 extern const struct raid6_calls raid6_intx8;
  32 extern const struct raid6_calls raid6_intx16;
  33 extern const struct raid6_calls raid6_intx32;
  34 extern const struct raid6_calls raid6_mmxx1;
  35 extern const struct raid6_calls raid6_mmxx2;
  36 extern const struct raid6_calls raid6_sse1x1;
  37 extern const struct raid6_calls raid6_sse1x2;
  38 extern const struct raid6_calls raid6_sse2x1;
  39 extern const struct raid6_calls raid6_sse2x2;
  40 extern const struct raid6_calls raid6_sse2x4;
  41 extern const struct raid6_calls raid6_altivec1;
  42 extern const struct raid6_calls raid6_altivec2;
  43 extern const struct raid6_calls raid6_altivec4;
  44 extern const struct raid6_calls raid6_altivec8;
  45
  46 const struct raid6_calls * const raid6_algos[] = {
  47         &raid6_intx1,
  48         &raid6_intx2,
  49         &raid6_intx4,
  50         &raid6_intx8,
  51 #if defined(__ia64__)
  52         &raid6_intx16,
  53         &raid6_intx32,
  54 #endif
  55 #if defined(__i386__) && !defined(__arch_um__)
  56         &raid6_mmxx1,
  57         &raid6_mmxx2,
  58         &raid6_sse1x1,
  59         &raid6_sse1x2,
  60         &raid6_sse2x1,
  61         &raid6_sse2x2,
  62 #endif
  63 #if defined(__x86_64__) && !defined(__arch_um__)
  64         &raid6_sse2x1,
  65         &raid6_sse2x2,
  66         &raid6_sse2x4,
  67 #endif
  68 #ifdef CONFIG_ALTIVEC
  69         &raid6_altivec1,
  70         &raid6_altivec2,
  71         &raid6_altivec4,
  72         &raid6_altivec8,
  73 #endif
  74         NULL
  75 };
  76
  77 #ifdef __KERNEL__
  78 #define RAID6_TIME_JIFFIES_LG2  4
  79 #else
  80 /* Need more time to be stable in userspace */
  81 #define RAID6_TIME_JIFFIES_LG2  9
  82 #endif
  83
  84 /* Try to pick the best algorithm */
  85 /* This code uses the gfmul table as convenient data set to abuse */
  86
  87 int __init raid6_select_algo(void)
  88 {
  89         const struct raid6_calls * const * algo;
  90         const struct raid6_calls * best;
  91         char *syndromes;
  92         void *dptrs[(65536/PAGE_SIZE)+2];
  93         int i, disks;
  94         unsigned long perf, bestperf;
  95         int bestprefer;
  96         unsigned long j0, j1;
  97
  98         disks = (65536/PAGE_SIZE)+2;
  99         for ( i = 0 ; i < disks-2 ; i++ ) {
 100                 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
 101         }
 102
 103         /* Normal code - use a 2-page allocation to avoid D$ conflict */
 104         syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
 105
 106         if ( !syndromes ) {
 107                 printk("raid6: Yikes!  No memory available.\n");
 108                 return -ENOMEM;
 109         }
 110
 111         dptrs[disks-2] = syndromes;
 112         dptrs[disks-1] = syndromes + PAGE_SIZE;
 113
 114         bestperf = 0;  bestprefer = 0;  best = NULL;
 115
 116         for ( algo = raid6_algos ; *algo ; algo++ ) {
 117                 if ( !(*algo)->valid || (*algo)->valid() ) {
 118                         perf = 0;
 119
 120                         preempt_disable();
 121                         j0 = jiffies;
 122                         while ( (j1 = jiffies) == j0 )
 123                                 cpu_relax();
 124                         while (time_before(jiffies,
 125                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 126                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
 127                                 perf++;
 128                         }
 129                         preempt_enable();
 130
 131                         if ( (*algo)->prefer > bestprefer ||
 132                              ((*algo)->prefer == bestprefer &&
 133                               perf > bestperf) ) {
 134                                 best = *algo;
 135                                 bestprefer = best->prefer;
 136                                 bestperf = perf;
 137                         }
 138                         printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
 139                                (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 140                 }
 141         }
 142
 143         if (best) {
 144                 printk("raid6: using algorithm %s (%ld MB/s)\n",
 145                        best->name,
 146                        (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
 147                 raid6_call = *best;
 148         } else
 149                 printk("raid6: Yikes!  No algorithm found!\n");
 150
 151         free_pages((unsigned long)syndromes, 1);
 152
 153         return best ? 0 : -EINVAL;
 154 }