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 #include <linux/module.h> 21 #ifndef __KERNEL__ 22 #include <sys/mman.h> 23 #include <stdio.h> 24 #else 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 &raid6_intx1, 38 &raid6_intx2, 39 &raid6_intx4, 40 &raid6_intx8, 41 #if defined(__ia64__) 42 &raid6_intx16, 43 &raid6_intx32, 44 #endif 45 #if defined(__i386__) && !defined(__arch_um__) 46 &raid6_mmxx1, 47 &raid6_mmxx2, 48 &raid6_sse1x1, 49 &raid6_sse1x2, 50 &raid6_sse2x1, 51 &raid6_sse2x2, 52 #endif 53 #if defined(__x86_64__) && !defined(__arch_um__) 54 &raid6_sse2x1, 55 &raid6_sse2x2, 56 &raid6_sse2x4, 57 #endif 58 #ifdef CONFIG_ALTIVEC 59 &raid6_altivec1, 60 &raid6_altivec2, 61 &raid6_altivec4, 62 &raid6_altivec8, 63 #endif 64 NULL 65 }; 66 67 #ifdef __KERNEL__ 68 #define RAID6_TIME_JIFFIES_LG2 4 69 #else 70 /* Need more time to be stable in userspace */ 71 #define RAID6_TIME_JIFFIES_LG2 9 72 #define time_before(x, y) ((x) < (y)) 73 #endif 74 75 /* Try to pick the best algorithm */ 76 /* This code uses the gfmul table as convenient data set to abuse */ 77 78 int __init raid6_select_algo(void) 79 { 80 const struct raid6_calls * const * algo; 81 const struct raid6_calls * best; 82 char *syndromes; 83 void *dptrs[(65536/PAGE_SIZE)+2]; 84 int i, disks; 85 unsigned long perf, bestperf; 86 int bestprefer; 87 unsigned long j0, j1; 88 89 disks = (65536/PAGE_SIZE)+2; 90 for ( i = 0 ; i < disks-2 ; i++ ) { 91 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i; 92 } 93 94 /* Normal code - use a 2-page allocation to avoid D$ conflict */ 95 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1); 96 97 if ( !syndromes ) { 98 printk("raid6: Yikes! No memory available.\n"); 99 return -ENOMEM; 100 } 101 102 dptrs[disks-2] = syndromes; 103 dptrs[disks-1] = syndromes + PAGE_SIZE; 104 105 bestperf = 0; bestprefer = 0; best = NULL; 106 107 for ( algo = raid6_algos ; *algo ; algo++ ) { 108 if ( !(*algo)->valid || (*algo)->valid() ) { 109 perf = 0; 110 111 preempt_disable(); 112 j0 = jiffies; 113 while ( (j1 = jiffies) == j0 ) 114 cpu_relax(); 115 while (time_before(jiffies, 116 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) { 117 (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs); 118 perf++; 119 } 120 preempt_enable(); 121 122 if ( (*algo)->prefer > bestprefer || 123 ((*algo)->prefer == bestprefer && 124 perf > bestperf) ) { 125 best = *algo; 126 bestprefer = best->prefer; 127 bestperf = perf; 128 } 129 printk("raid6: %-8s %5ld MB/s\n", (*algo)->name, 130 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2)); 131 } 132 } 133 134 if (best) { 135 printk("raid6: using algorithm %s (%ld MB/s)\n", 136 best->name, 137 (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2)); 138 raid6_call = *best; 139 } else 140 printk("raid6: Yikes! No algorithm found!\n"); 141 142 free_pages((unsigned long)syndromes, 1); 143 144 return best ? 0 : -EINVAL; 145 } 146 147 static void raid6_exit(void) 148 { 149 do { } while (0); 150 } 151 152 subsys_initcall(raid6_select_algo); 153 module_exit(raid6_exit); 154 MODULE_LICENSE("GPL"); 155 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations"); 156