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
xor_blocks(unsigned int src_count,unsigned int bytes,void * dest,void ** srcs)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
do_xor_speed(struct xor_block_template * tmpl,void * b1,void * b2)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
calibrate_xor_blocks(void)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
xor_exit(void)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