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 <linux/preempt.h> 25 #include <asm/xor.h> 26 27 /* The xor routines to use. */ 28 static struct xor_block_template *active_template; 29 30 void 31 xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs) 32 { 33 unsigned long *p1, *p2, *p3, *p4; 34 35 p1 = (unsigned long *) srcs[0]; 36 if (src_count == 1) { 37 active_template->do_2(bytes, dest, p1); 38 return; 39 } 40 41 p2 = (unsigned long *) srcs[1]; 42 if (src_count == 2) { 43 active_template->do_3(bytes, dest, p1, p2); 44 return; 45 } 46 47 p3 = (unsigned long *) srcs[2]; 48 if (src_count == 3) { 49 active_template->do_4(bytes, dest, p1, p2, p3); 50 return; 51 } 52 53 p4 = (unsigned long *) srcs[3]; 54 active_template->do_5(bytes, dest, p1, p2, p3, p4); 55 } 56 EXPORT_SYMBOL(xor_blocks); 57 58 /* Set of all registered templates. */ 59 static struct xor_block_template *__initdata template_list; 60 61 #define BENCH_SIZE (PAGE_SIZE) 62 63 static void __init 64 do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2) 65 { 66 int speed; 67 unsigned long now, j; 68 int i, count, max; 69 70 tmpl->next = template_list; 71 template_list = tmpl; 72 73 preempt_disable(); 74 75 /* 76 * Count the number of XORs done during a whole jiffy, and use 77 * this to calculate the speed of checksumming. We use a 2-page 78 * allocation to have guaranteed color L1-cache layout. 79 */ 80 max = 0; 81 for (i = 0; i < 5; i++) { 82 j = jiffies; 83 count = 0; 84 while ((now = jiffies) == j) 85 cpu_relax(); 86 while (time_before(jiffies, now + 1)) { 87 mb(); /* prevent loop optimzation */ 88 tmpl->do_2(BENCH_SIZE, b1, b2); 89 mb(); 90 count++; 91 mb(); 92 } 93 if (count > max) 94 max = count; 95 } 96 97 preempt_enable(); 98 99 speed = max * (HZ * BENCH_SIZE / 1024); 100 tmpl->speed = speed; 101 102 printk(KERN_INFO " %-10s: %5d.%03d MB/sec\n", tmpl->name, 103 speed / 1000, speed % 1000); 104 } 105 106 static int __init 107 calibrate_xor_blocks(void) 108 { 109 void *b1, *b2; 110 struct xor_block_template *f, *fastest; 111 112 /* 113 * Note: Since the memory is not actually used for _anything_ but to 114 * test the XOR speed, we don't really want kmemcheck to warn about 115 * reading uninitialized bytes here. 116 */ 117 b1 = (void *) __get_free_pages(GFP_KERNEL | __GFP_NOTRACK, 2); 118 if (!b1) { 119 printk(KERN_WARNING "xor: Yikes! No memory available.\n"); 120 return -ENOMEM; 121 } 122 b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE; 123 124 /* 125 * If this arch/cpu has a short-circuited selection, don't loop through 126 * all the possible functions, just test the best one 127 */ 128 129 fastest = NULL; 130 131 #ifdef XOR_SELECT_TEMPLATE 132 fastest = XOR_SELECT_TEMPLATE(fastest); 133 #endif 134 135 #define xor_speed(templ) do_xor_speed((templ), b1, b2) 136 137 if (fastest) { 138 printk(KERN_INFO "xor: automatically using best " 139 "checksumming function:\n"); 140 xor_speed(fastest); 141 goto out; 142 } else { 143 printk(KERN_INFO "xor: measuring software checksum speed\n"); 144 XOR_TRY_TEMPLATES; 145 fastest = template_list; 146 for (f = fastest; f; f = f->next) 147 if (f->speed > fastest->speed) 148 fastest = f; 149 } 150 151 printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n", 152 fastest->name, fastest->speed / 1000, fastest->speed % 1000); 153 154 #undef xor_speed 155 156 out: 157 free_pages((unsigned long)b1, 2); 158 159 active_template = fastest; 160 return 0; 161 } 162 163 static __exit void xor_exit(void) { } 164 165 MODULE_LICENSE("GPL"); 166 167 /* when built-in xor.o must initialize before drivers/md/md.o */ 168 core_initcall(calibrate_xor_blocks); 169 module_exit(xor_exit); 170