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/gfp.h> 25#if !RAID6_USE_EMPTY_ZERO_PAGE 26/* In .bss so it's zeroed */ 27const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256))); 28EXPORT_SYMBOL(raid6_empty_zero_page); 29#endif 30#endif 31 32struct raid6_calls raid6_call; 33EXPORT_SYMBOL_GPL(raid6_call); 34 35const struct raid6_calls * const raid6_algos[] = { 36 &raid6_intx1, 37 &raid6_intx2, 38 &raid6_intx4, 39 &raid6_intx8, 40#if defined(__ia64__) 41 &raid6_intx16, 42 &raid6_intx32, 43#endif 44#if defined(__i386__) && !defined(__arch_um__) 45 &raid6_mmxx1, 46 &raid6_mmxx2, 47 &raid6_sse1x1, 48 &raid6_sse1x2, 49 &raid6_sse2x1, 50 &raid6_sse2x2, 51#endif 52#if defined(__x86_64__) && !defined(__arch_um__) 53 &raid6_sse2x1, 54 &raid6_sse2x2, 55 &raid6_sse2x4, 56#endif 57#ifdef CONFIG_ALTIVEC 58 &raid6_altivec1, 59 &raid6_altivec2, 60 &raid6_altivec4, 61 &raid6_altivec8, 62#endif 63 NULL 64}; 65 66#ifdef __KERNEL__ 67#define RAID6_TIME_JIFFIES_LG2 4 68#else 69/* Need more time to be stable in userspace */ 70#define RAID6_TIME_JIFFIES_LG2 9 71#define time_before(x, y) ((x) < (y)) 72#endif 73 74/* Try to pick the best algorithm */ 75/* This code uses the gfmul table as convenient data set to abuse */ 76 77int __init raid6_select_algo(void) 78{ 79 const struct raid6_calls * const * algo; 80 const struct raid6_calls * best; 81 char *syndromes; 82 void *dptrs[(65536/PAGE_SIZE)+2]; 83 int i, disks; 84 unsigned long perf, bestperf; 85 int bestprefer; 86 unsigned long j0, j1; 87 88 disks = (65536/PAGE_SIZE)+2; 89 for ( i = 0 ; i < disks-2 ; i++ ) { 90 dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i; 91 } 92 93 /* Normal code - use a 2-page allocation to avoid D$ conflict */ 94 syndromes = (void *) __get_free_pages(GFP_KERNEL, 1); 95 96 if ( !syndromes ) { 97 printk("raid6: Yikes! No memory available.\n"); 98 return -ENOMEM; 99 } 100 101 dptrs[disks-2] = syndromes; 102 dptrs[disks-1] = syndromes + PAGE_SIZE; 103 104 bestperf = 0; bestprefer = 0; best = NULL; 105 106 for ( algo = raid6_algos ; *algo ; algo++ ) { 107 if ( !(*algo)->valid || (*algo)->valid() ) { 108 perf = 0; 109 110 preempt_disable(); 111 j0 = jiffies; 112 while ( (j1 = jiffies) == j0 ) 113 cpu_relax(); 114 while (time_before(jiffies, 115 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) { 116 (*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs); 117 perf++; 118 } 119 preempt_enable(); 120 121 if ( (*algo)->prefer > bestprefer || 122 ((*algo)->prefer == bestprefer && 123 perf > bestperf) ) { 124 best = *algo; 125 bestprefer = best->prefer; 126 bestperf = perf; 127 } 128 printk("raid6: %-8s %5ld MB/s\n", (*algo)->name, 129 (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2)); 130 } 131 } 132 133 if (best) { 134 printk("raid6: using algorithm %s (%ld MB/s)\n", 135 best->name, 136 (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2)); 137 raid6_call = *best; 138 } else 139 printk("raid6: Yikes! No algorithm found!\n"); 140 141 free_pages((unsigned long)syndromes, 1); 142 143 return best ? 0 : -EINVAL; 144} 145 146static void raid6_exit(void) 147{ 148 do { } while (0); 149} 150 151subsys_initcall(raid6_select_algo); 152module_exit(raid6_exit); 153MODULE_LICENSE("GPL"); 154MODULE_DESCRIPTION("RAID6 Q-syndrome calculations"); 155