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