tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/raid/md.h>
22#include <linux/raid/xor.h>
23#include <asm/xor.h>
24
25/* The xor routines to use. */
26static struct xor_block_template *active_template;
27
28void
29xor_block(unsigned int count, unsigned int bytes, void **ptr)
30{
31 unsigned long *p0, *p1, *p2, *p3, *p4;
32
33 p0 = (unsigned long *) ptr[0];
34 p1 = (unsigned long *) ptr[1];
35 if (count == 2) {
36 active_template->do_2(bytes, p0, p1);
37 return;
38 }
39
40 p2 = (unsigned long *) ptr[2];
41 if (count == 3) {
42 active_template->do_3(bytes, p0, p1, p2);
43 return;
44 }
45
46 p3 = (unsigned long *) ptr[3];
47 if (count == 4) {
48 active_template->do_4(bytes, p0, p1, p2, p3);
49 return;
50 }
51
52 p4 = (unsigned long *) ptr[4];
53 active_template->do_5(bytes, p0, p1, p2, p3, p4);
54}
55
56/* Set of all registered templates. */
57static struct xor_block_template *template_list;
58
59#define BENCH_SIZE (PAGE_SIZE)
60
61static void
62do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
63{
64 int speed;
65 unsigned long now;
66 int i, count, max;
67
68 tmpl->next = template_list;
69 template_list = tmpl;
70
71 /*
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.
75 */
76 max = 0;
77 for (i = 0; i < 5; i++) {
78 now = jiffies;
79 count = 0;
80 while (jiffies == now) {
81 mb();
82 tmpl->do_2(BENCH_SIZE, b1, b2);
83 mb();
84 count++;
85 mb();
86 }
87 if (count > max)
88 max = count;
89 }
90
91 speed = max * (HZ * BENCH_SIZE / 1024);
92 tmpl->speed = speed;
93
94 printk(" %-10s: %5d.%03d MB/sec\n", tmpl->name,
95 speed / 1000, speed % 1000);
96}
97
98static int
99calibrate_xor_block(void)
100{
101 void *b1, *b2;
102 struct xor_block_template *f, *fastest;
103
104 b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
105 if (! b1) {
106 printk("raid5: Yikes! No memory available.\n");
107 return -ENOMEM;
108 }
109 b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
110
111 /*
112 * If this arch/cpu has a short-circuited selection, don't loop through all
113 * the possible functions, just test the best one
114 */
115
116 fastest = NULL;
117
118#ifdef XOR_SELECT_TEMPLATE
119 fastest = XOR_SELECT_TEMPLATE(fastest);
120#endif
121
122#define xor_speed(templ) do_xor_speed((templ), b1, b2)
123
124 if (fastest) {
125 printk(KERN_INFO "raid5: automatically using best checksumming function: %s\n",
126 fastest->name);
127 xor_speed(fastest);
128 } else {
129 printk(KERN_INFO "raid5: measuring checksumming speed\n");
130 XOR_TRY_TEMPLATES;
131 fastest = template_list;
132 for (f = fastest; f; f = f->next)
133 if (f->speed > fastest->speed)
134 fastest = f;
135 }
136
137 printk("raid5: using function: %s (%d.%03d MB/sec)\n",
138 fastest->name, fastest->speed / 1000, fastest->speed % 1000);
139
140#undef xor_speed
141
142 free_pages((unsigned long)b1, 2);
143
144 active_template = fastest;
145 return 0;
146}
147
148static __exit void xor_exit(void) { }
149
150EXPORT_SYMBOL(xor_block);
151MODULE_LICENSE("GPL");
152
153module_init(calibrate_xor_block);
154module_exit(xor_exit);