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/gfp.h> 22 #include <linux/raid/xor.h> 23 #include <linux/jiffies.h> 24 #include <asm/xor.h> 25 26 /* The xor routines to use. */ 27 static struct xor_block_template *active_template; 28 29 void 30 xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs) 31 { 32 unsigned long *p1, *p2, *p3, *p4; 33 34 p1 = (unsigned long *) srcs[0]; 35 if (src_count == 1) { 36 active_template->do_2(bytes, dest, p1); 37 return; 38 } 39 40 p2 = (unsigned long *) srcs[1]; 41 if (src_count == 2) { 42 active_template->do_3(bytes, dest, p1, p2); 43 return; 44 } 45 46 p3 = (unsigned long *) srcs[2]; 47 if (src_count == 3) { 48 active_template->do_4(bytes, dest, p1, p2, p3); 49 return; 50 } 51 52 p4 = (unsigned long *) srcs[3]; 53 active_template->do_5(bytes, dest, p1, p2, p3, p4); 54 } 55 EXPORT_SYMBOL(xor_blocks); 56 57 /* Set of all registered templates. */ 58 static struct xor_block_template *template_list; 59 60 #define BENCH_SIZE (PAGE_SIZE) 61 62 static void 63 do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2) 64 { 65 int speed; 66 unsigned long now; 67 int i, count, max; 68 69 tmpl->next = template_list; 70 template_list = tmpl; 71 72 /* 73 * Count the number of XORs done during a whole jiffy, and use 74 * this to calculate the speed of checksumming. We use a 2-page 75 * allocation to have guaranteed color L1-cache layout. 76 */ 77 max = 0; 78 for (i = 0; i < 5; i++) { 79 now = jiffies; 80 count = 0; 81 while (jiffies == now) { 82 mb(); /* prevent loop optimzation */ 83 tmpl->do_2(BENCH_SIZE, b1, b2); 84 mb(); 85 count++; 86 mb(); 87 } 88 if (count > max) 89 max = count; 90 } 91 92 speed = max * (HZ * BENCH_SIZE / 1024); 93 tmpl->speed = speed; 94 95 printk(KERN_INFO " %-10s: %5d.%03d MB/sec\n", tmpl->name, 96 speed / 1000, speed % 1000); 97 } 98 99 static int __init 100 calibrate_xor_blocks(void) 101 { 102 void *b1, *b2; 103 struct xor_block_template *f, *fastest; 104 105 /* 106 * Note: Since the memory is not actually used for _anything_ but to 107 * test the XOR speed, we don't really want kmemcheck to warn about 108 * reading uninitialized bytes here. 109 */ 110 b1 = (void *) __get_free_pages(GFP_KERNEL | __GFP_NOTRACK, 2); 111 if (!b1) { 112 printk(KERN_WARNING "xor: Yikes! No memory available.\n"); 113 return -ENOMEM; 114 } 115 b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE; 116 117 /* 118 * If this arch/cpu has a short-circuited selection, don't loop through 119 * all the possible functions, just test the best one 120 */ 121 122 fastest = NULL; 123 124 #ifdef XOR_SELECT_TEMPLATE 125 fastest = XOR_SELECT_TEMPLATE(fastest); 126 #endif 127 128 #define xor_speed(templ) do_xor_speed((templ), b1, b2) 129 130 if (fastest) { 131 printk(KERN_INFO "xor: automatically using best " 132 "checksumming function: %s\n", 133 fastest->name); 134 xor_speed(fastest); 135 } else { 136 printk(KERN_INFO "xor: measuring software checksum speed\n"); 137 XOR_TRY_TEMPLATES; 138 fastest = template_list; 139 for (f = fastest; f; f = f->next) 140 if (f->speed > fastest->speed) 141 fastest = f; 142 } 143 144 printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n", 145 fastest->name, fastest->speed / 1000, fastest->speed % 1000); 146 147 #undef xor_speed 148 149 free_pages((unsigned long)b1, 2); 150 151 active_template = fastest; 152 return 0; 153 } 154 155 static __exit void xor_exit(void) { } 156 157 MODULE_LICENSE("GPL"); 158 159 /* when built-in xor.o must initialize before drivers/md/md.o */ 160 core_initcall(calibrate_xor_blocks); 161 module_exit(xor_exit); 162