1 /* -*- linux-c -*- ------------------------------------------------------- *
3 * Copyright 2002 H. Peter Anvin - All Rights Reserved
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.
11 * ----------------------------------------------------------------------- */
16 * Algorithm list and algorithm selection for RAID-6
24 struct raid6_calls raid6_call;
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;
41 const struct raid6_calls * const raid6_algos[] = {
58 #if defined(__x86_64__)
67 #define RAID6_TIME_JIFFIES_LG2 4
69 /* Need more time to be stable in userspace */
70 #define RAID6_TIME_JIFFIES_LG2 9
73 /* Try to pick the best algorithm */
74 /* This code uses the gfmul table as convenient data set to abuse */
76 int __init raid6_select_algo(void)
78 const struct raid6_calls * const * algo;
79 const struct raid6_calls * best;
81 void *dptrs[(65536/PAGE_SIZE)+2];
83 unsigned long perf, bestperf;
87 disks = (65536/PAGE_SIZE)+2;
88 for ( i = 0 ; i < disks-2 ; i++ ) {
89 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
92 /* Normal code - use a 2-page allocation to avoid D$ conflict */
93 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
96 printk("raid6: Yikes! No memory available.\n");
100 dptrs[disks-2] = syndromes;
101 dptrs[disks-1] = syndromes + PAGE_SIZE;
103 bestperf = 0; bestprefer = 0; best = NULL;
105 for ( algo = raid6_algos ; *algo ; algo++ ) {
106 if ( !(*algo)->valid || (*algo)->valid() ) {
111 while ( (j1 = jiffies) == j0 )
113 while ( (jiffies-j1) < (1 << RAID6_TIME_JIFFIES_LG2) ) {
114 (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
119 if ( (*algo)->prefer > bestprefer ||
120 ((*algo)->prefer == bestprefer &&
123 bestprefer = best->prefer;
126 printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
127 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
132 printk("raid6: using algorithm %s (%ld MB/s)\n",
134 (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
136 printk("raid6: Yikes! No algorithm found!\n");
140 free_pages((unsigned long)syndromes, 1);
142 return best ? 0 : -EINVAL;