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CommitLineData
1da177e4
LT
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>
5a0e3ad6 21#include <linux/gfp.h>
1da177e4 22#include <linux/raid/xor.h>
bff61975 23#include <linux/jiffies.h>
56a51991 24#include <linux/preempt.h>
1da177e4
LT
25#include <asm/xor.h>
26
27c4d548
HX
27#ifndef XOR_SELECT_TEMPLATE
28#define XOR_SELECT_TEMPLATE(x) (x)
29#endif
30
1da177e4
LT
31/* The xor routines to use. */
32static struct xor_block_template *active_template;
33
34void
9bc89cd8 35xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs)
1da177e4 36{
9bc89cd8 37 unsigned long *p1, *p2, *p3, *p4;
1da177e4 38
9bc89cd8
DW
39 p1 = (unsigned long *) srcs[0];
40 if (src_count == 1) {
41 active_template->do_2(bytes, dest, p1);
1da177e4
LT
42 return;
43 }
44
9bc89cd8
DW
45 p2 = (unsigned long *) srcs[1];
46 if (src_count == 2) {
47 active_template->do_3(bytes, dest, p1, p2);
1da177e4
LT
48 return;
49 }
50
9bc89cd8
DW
51 p3 = (unsigned long *) srcs[2];
52 if (src_count == 3) {
53 active_template->do_4(bytes, dest, p1, p2, p3);
1da177e4
LT
54 return;
55 }
56
9bc89cd8
DW
57 p4 = (unsigned long *) srcs[3];
58 active_template->do_5(bytes, dest, p1, p2, p3, p4);
1da177e4 59}
685784aa 60EXPORT_SYMBOL(xor_blocks);
1da177e4
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61
62/* Set of all registered templates. */
af7cf25d 63static struct xor_block_template *__initdata template_list;
1da177e4
LT
64
65#define BENCH_SIZE (PAGE_SIZE)
66
af7cf25d 67static void __init
1da177e4
LT
68do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
69{
70 int speed;
6a328475 71 unsigned long now, j;
1da177e4
LT
72 int i, count, max;
73
74 tmpl->next = template_list;
75 template_list = tmpl;
76
56a51991
JK
77 preempt_disable();
78
1da177e4
LT
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++) {
6a328475 86 j = jiffies;
1da177e4 87 count = 0;
6a328475
JK
88 while ((now = jiffies) == j)
89 cpu_relax();
90 while (time_before(jiffies, now + 1)) {
685784aa 91 mb(); /* prevent loop optimzation */
1da177e4
LT
92 tmpl->do_2(BENCH_SIZE, b1, b2);
93 mb();
94 count++;
95 mb();
96 }
97 if (count > max)
98 max = count;
99 }
100
56a51991
JK
101 preempt_enable();
102
1da177e4
LT
103 speed = max * (HZ * BENCH_SIZE / 1024);
104 tmpl->speed = speed;
105
685784aa 106 printk(KERN_INFO " %-10s: %5d.%03d MB/sec\n", tmpl->name,
1da177e4
LT
107 speed / 1000, speed % 1000);
108}
109
685784aa
DW
110static int __init
111calibrate_xor_blocks(void)
1da177e4
LT
112{
113 void *b1, *b2;
114 struct xor_block_template *f, *fastest;
115
27c4d548 116 fastest = XOR_SELECT_TEMPLATE(NULL);
39457acd 117
39457acd
MS
118 if (fastest) {
119 printk(KERN_INFO "xor: automatically using best "
120 "checksumming function %-10s\n",
121 fastest->name);
122 goto out;
123 }
39457acd 124
33f65df7
VN
125 /*
126 * Note: Since the memory is not actually used for _anything_ but to
127 * test the XOR speed, we don't really want kmemcheck to warn about
128 * reading uninitialized bytes here.
129 */
130 b1 = (void *) __get_free_pages(GFP_KERNEL | __GFP_NOTRACK, 2);
685784aa
DW
131 if (!b1) {
132 printk(KERN_WARNING "xor: Yikes! No memory available.\n");
1da177e4
LT
133 return -ENOMEM;
134 }
135 b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
136
137 /*
685784aa
DW
138 * If this arch/cpu has a short-circuited selection, don't loop through
139 * all the possible functions, just test the best one
1da177e4
LT
140 */
141
1da177e4
LT
142#define xor_speed(templ) do_xor_speed((templ), b1, b2)
143
39457acd
MS
144 printk(KERN_INFO "xor: measuring software checksum speed\n");
145 XOR_TRY_TEMPLATES;
146 fastest = template_list;
147 for (f = fastest; f; f = f->next)
148 if (f->speed > fastest->speed)
149 fastest = f;
1da177e4 150
685784aa 151 printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n",
1da177e4
LT
152 fastest->name, fastest->speed / 1000, fastest->speed % 1000);
153
154#undef xor_speed
155
156 free_pages((unsigned long)b1, 2);
39457acd 157out:
1da177e4
LT
158 active_template = fastest;
159 return 0;
160}
161
162static __exit void xor_exit(void) { }
163
1da177e4
LT
164MODULE_LICENSE("GPL");
165
685784aa
DW
166/* when built-in xor.o must initialize before drivers/md/md.o */
167core_initcall(calibrate_xor_blocks);
1da177e4 168module_exit(xor_exit);