2 * xor.c : Multiple Devices driver for Linux
4 * Copyright (C) 1996, 1997, 1998, 1999, 2000,
5 * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson.
7 * Dispatch optimized RAID-5 checksumming functions.
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)
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.
20 #include <linux/module.h>
21 #include <linux/raid/xor.h>
22 #include <linux/jiffies.h>
25 /* The xor routines to use. */
26 static struct xor_block_template *active_template;
29 xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs)
31 unsigned long *p1, *p2, *p3, *p4;
33 p1 = (unsigned long *) srcs[0];
35 active_template->do_2(bytes, dest, p1);
39 p2 = (unsigned long *) srcs[1];
41 active_template->do_3(bytes, dest, p1, p2);
45 p3 = (unsigned long *) srcs[2];
47 active_template->do_4(bytes, dest, p1, p2, p3);
51 p4 = (unsigned long *) srcs[3];
52 active_template->do_5(bytes, dest, p1, p2, p3, p4);
54 EXPORT_SYMBOL(xor_blocks);
56 /* Set of all registered templates. */
57 static struct xor_block_template *template_list;
59 #define BENCH_SIZE (PAGE_SIZE)
62 do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
68 tmpl->next = template_list;
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.
77 for (i = 0; i < 5; i++) {
80 while (jiffies == now) {
81 mb(); /* prevent loop optimzation */
82 tmpl->do_2(BENCH_SIZE, b1, b2);
91 speed = max * (HZ * BENCH_SIZE / 1024);
94 printk(KERN_INFO " %-10s: %5d.%03d MB/sec\n", tmpl->name,
95 speed / 1000, speed % 1000);
99 calibrate_xor_blocks(void)
102 struct xor_block_template *f, *fastest;
104 b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
106 printk(KERN_WARNING "xor: Yikes! No memory available.\n");
109 b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
112 * If this arch/cpu has a short-circuited selection, don't loop through
113 * all the possible functions, just test the best one
118 #ifdef XOR_SELECT_TEMPLATE
119 fastest = XOR_SELECT_TEMPLATE(fastest);
122 #define xor_speed(templ) do_xor_speed((templ), b1, b2)
125 printk(KERN_INFO "xor: automatically using best "
126 "checksumming function: %s\n",
130 printk(KERN_INFO "xor: measuring software checksum speed\n");
132 fastest = template_list;
133 for (f = fastest; f; f = f->next)
134 if (f->speed > fastest->speed)
138 printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n",
139 fastest->name, fastest->speed / 1000, fastest->speed % 1000);
143 free_pages((unsigned long)b1, 2);
145 active_template = fastest;
149 static __exit void xor_exit(void) { }
151 MODULE_LICENSE("GPL");
153 /* when built-in xor.o must initialize before drivers/md/md.o */
154 core_initcall(calibrate_xor_blocks);
155 module_exit(xor_exit);