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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 | /* * xor.c : Multiple Devices driver for Linux * * Copyright (C) 1996, 1997, 1998, 1999, 2000, * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson. * * Dispatch optimized RAID-5 checksumming functions. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2, or (at your option) * any later version. * * You should have received a copy of the GNU General Public License * (for example /usr/src/linux/COPYING); if not, write to the Free * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #define BH_TRACE 0 #include <linux/module.h> #include <linux/gfp.h> #include <linux/raid/xor.h> #include <linux/jiffies.h> #include <linux/preempt.h> #include <asm/xor.h> /* The xor routines to use. */ static struct xor_block_template *active_template; void xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs) { unsigned long *p1, *p2, *p3, *p4; p1 = (unsigned long *) srcs[0]; if (src_count == 1) { active_template->do_2(bytes, dest, p1); return; } p2 = (unsigned long *) srcs[1]; if (src_count == 2) { active_template->do_3(bytes, dest, p1, p2); return; } p3 = (unsigned long *) srcs[2]; if (src_count == 3) { active_template->do_4(bytes, dest, p1, p2, p3); return; } p4 = (unsigned long *) srcs[3]; active_template->do_5(bytes, dest, p1, p2, p3, p4); } EXPORT_SYMBOL(xor_blocks); /* Set of all registered templates. */ static struct xor_block_template *__initdata template_list; #define BENCH_SIZE (PAGE_SIZE) static void __init do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2) { int speed; unsigned long now, j; int i, count, max; tmpl->next = template_list; template_list = tmpl; preempt_disable(); /* * Count the number of XORs done during a whole jiffy, and use * this to calculate the speed of checksumming. We use a 2-page * allocation to have guaranteed color L1-cache layout. */ max = 0; for (i = 0; i < 5; i++) { j = jiffies; count = 0; while ((now = jiffies) == j) cpu_relax(); while (time_before(jiffies, now + 1)) { mb(); /* prevent loop optimzation */ tmpl->do_2(BENCH_SIZE, b1, b2); mb(); count++; mb(); } if (count > max) max = count; } preempt_enable(); speed = max * (HZ * BENCH_SIZE / 1024); tmpl->speed = speed; printk(KERN_INFO " %-10s: %5d.%03d MB/sec\n", tmpl->name, speed / 1000, speed % 1000); } static int __init calibrate_xor_blocks(void) { void *b1, *b2; struct xor_block_template *f, *fastest; /* * Note: Since the memory is not actually used for _anything_ but to * test the XOR speed, we don't really want kmemcheck to warn about * reading uninitialized bytes here. */ b1 = (void *) __get_free_pages(GFP_KERNEL | __GFP_NOTRACK, 2); if (!b1) { printk(KERN_WARNING "xor: Yikes! No memory available.\n"); return -ENOMEM; } b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE; /* * If this arch/cpu has a short-circuited selection, don't loop through * all the possible functions, just test the best one */ fastest = NULL; #ifdef XOR_SELECT_TEMPLATE fastest = XOR_SELECT_TEMPLATE(fastest); #endif #define xor_speed(templ) do_xor_speed((templ), b1, b2) if (fastest) { printk(KERN_INFO "xor: automatically using best " "checksumming function:\n"); xor_speed(fastest); goto out; } else { printk(KERN_INFO "xor: measuring software checksum speed\n"); XOR_TRY_TEMPLATES; fastest = template_list; for (f = fastest; f; f = f->next) if (f->speed > fastest->speed) fastest = f; } printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n", fastest->name, fastest->speed / 1000, fastest->speed % 1000); #undef xor_speed out: free_pages((unsigned long)b1, 2); active_template = fastest; return 0; } static __exit void xor_exit(void) { } MODULE_LICENSE("GPL"); /* when built-in xor.o must initialize before drivers/md/md.o */ core_initcall(calibrate_xor_blocks); module_exit(xor_exit); |