1 /* 2 * xor.c : Multiple Devices driver for Linux 3 * 4 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 5 * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson. 6 * 7 * Dispatch optimized RAID-5 checksumming functions. 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2, or (at your option) 12 * any later version. 13 * 14 * You should have received a copy of the GNU General Public License 15 * (for example /usr/src/linux/COPYING); if not, write to the Free 16 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 17 */ 18 19 #define BH_TRACE 0 20 #include <linux/module.h> 21 #include <linux/raid/md.h> 22 #include <linux/raid/xor.h> 23 #include <asm/xor.h> 24 25 /* The xor routines to use. */ 26 static struct xor_block_template *active_template; 27 28 void 29 xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs) 30 { 31 unsigned long *p1, *p2, *p3, *p4; 32 33 p1 = (unsigned long *) srcs[0]; 34 if (src_count == 1) { 35 active_template->do_2(bytes, dest, p1); 36 return; 37 } 38 39 p2 = (unsigned long *) srcs[1]; 40 if (src_count == 2) { 41 active_template->do_3(bytes, dest, p1, p2); 42 return; 43 } 44 45 p3 = (unsigned long *) srcs[2]; 46 if (src_count == 3) { 47 active_template->do_4(bytes, dest, p1, p2, p3); 48 return; 49 } 50 51 p4 = (unsigned long *) srcs[3]; 52 active_template->do_5(bytes, dest, p1, p2, p3, p4); 53 } 54 EXPORT_SYMBOL(xor_blocks); 55 56 /* Set of all registered templates. */ 57 static struct xor_block_template *template_list; 58 59 #define BENCH_SIZE (PAGE_SIZE) 60 61 static void 62 do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2) 63 { 64 int speed; 65 unsigned long now; 66 int i, count, max; 67 68 tmpl->next = template_list; 69 template_list = tmpl; 70 71 /* 72 * Count the number of XORs done during a whole jiffy, and use 73 * this to calculate the speed of checksumming. We use a 2-page 74 * allocation to have guaranteed color L1-cache layout. 75 */ 76 max = 0; 77 for (i = 0; i < 5; i++) { 78 now = jiffies; 79 count = 0; 80 while (jiffies == now) { 81 mb(); /* prevent loop optimzation */ 82 tmpl->do_2(BENCH_SIZE, b1, b2); 83 mb(); 84 count++; 85 mb(); 86 } 87 if (count > max) 88 max = count; 89 } 90 91 speed = max * (HZ * BENCH_SIZE / 1024); 92 tmpl->speed = speed; 93 94 printk(KERN_INFO " %-10s: %5d.%03d MB/sec\n", tmpl->name, 95 speed / 1000, speed % 1000); 96 } 97 98 static int __init 99 calibrate_xor_blocks(void) 100 { 101 void *b1, *b2; 102 struct xor_block_template *f, *fastest; 103 104 b1 = (void *) __get_free_pages(GFP_KERNEL, 2); 105 if (!b1) { 106 printk(KERN_WARNING "xor: Yikes! No memory available.\n"); 107 return -ENOMEM; 108 } 109 b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE; 110 111 /* 112 * If this arch/cpu has a short-circuited selection, don't loop through 113 * all the possible functions, just test the best one 114 */ 115 116 fastest = NULL; 117 118 #ifdef XOR_SELECT_TEMPLATE 119 fastest = XOR_SELECT_TEMPLATE(fastest); 120 #endif 121 122 #define xor_speed(templ) do_xor_speed((templ), b1, b2) 123 124 if (fastest) { 125 printk(KERN_INFO "xor: automatically using best " 126 "checksumming function: %s\n", 127 fastest->name); 128 xor_speed(fastest); 129 } else { 130 printk(KERN_INFO "xor: measuring software checksum speed\n"); 131 XOR_TRY_TEMPLATES; 132 fastest = template_list; 133 for (f = fastest; f; f = f->next) 134 if (f->speed > fastest->speed) 135 fastest = f; 136 } 137 138 printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n", 139 fastest->name, fastest->speed / 1000, fastest->speed % 1000); 140 141 #undef xor_speed 142 143 free_pages((unsigned long)b1, 2); 144 145 active_template = fastest; 146 return 0; 147 } 148 149 static __exit void xor_exit(void) { } 150 151 MODULE_LICENSE("GPL"); 152 153 /* when built-in xor.o must initialize before drivers/md/md.o */ 154 core_initcall(calibrate_xor_blocks); 155 module_exit(xor_exit); 156