1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * xor.c : Multiple Devices driver for Linux |
4 | * |
5 | * Copyright (C) 1996, 1997, 1998, 1999, 2000, |
6 | * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson. |
7 | * |
8 | * Dispatch optimized RAID-5 checksumming functions. |
9 | */ |
10 | |
11 | #define BH_TRACE 0 |
12 | #include <linux/module.h> |
13 | #include <linux/gfp.h> |
14 | #include <linux/raid/xor.h> |
15 | #include <linux/jiffies.h> |
16 | #include <linux/preempt.h> |
17 | #include <asm/xor.h> |
18 | |
19 | #ifndef XOR_SELECT_TEMPLATE |
20 | #define XOR_SELECT_TEMPLATE(x) (x) |
21 | #endif |
22 | |
23 | /* The xor routines to use. */ |
24 | static struct xor_block_template *active_template; |
25 | |
26 | void |
27 | xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs) |
28 | { |
29 | unsigned long *p1, *p2, *p3, *p4; |
30 | |
31 | p1 = (unsigned long *) srcs[0]; |
32 | if (src_count == 1) { |
33 | active_template->do_2(bytes, dest, p1); |
34 | return; |
35 | } |
36 | |
37 | p2 = (unsigned long *) srcs[1]; |
38 | if (src_count == 2) { |
39 | active_template->do_3(bytes, dest, p1, p2); |
40 | return; |
41 | } |
42 | |
43 | p3 = (unsigned long *) srcs[2]; |
44 | if (src_count == 3) { |
45 | active_template->do_4(bytes, dest, p1, p2, p3); |
46 | return; |
47 | } |
48 | |
49 | p4 = (unsigned long *) srcs[3]; |
50 | active_template->do_5(bytes, dest, p1, p2, p3, p4); |
51 | } |
52 | EXPORT_SYMBOL(xor_blocks); |
53 | |
54 | /* Set of all registered templates. */ |
55 | static struct xor_block_template *__initdata template_list; |
56 | |
57 | #ifndef MODULE |
58 | static void __init do_xor_register(struct xor_block_template *tmpl) |
59 | { |
60 | tmpl->next = template_list; |
61 | template_list = tmpl; |
62 | } |
63 | |
64 | static int __init register_xor_blocks(void) |
65 | { |
66 | active_template = XOR_SELECT_TEMPLATE(NULL); |
67 | |
68 | if (!active_template) { |
69 | #define xor_speed do_xor_register |
70 | // register all the templates and pick the first as the default |
71 | XOR_TRY_TEMPLATES; |
72 | #undef xor_speed |
73 | active_template = template_list; |
74 | } |
75 | return 0; |
76 | } |
77 | #endif |
78 | |
79 | #define BENCH_SIZE 4096 |
80 | #define REPS 800U |
81 | |
82 | static void __init |
83 | do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2) |
84 | { |
85 | int speed; |
86 | int i, j; |
87 | ktime_t min, start, diff; |
88 | |
89 | tmpl->next = template_list; |
90 | template_list = tmpl; |
91 | |
92 | preempt_disable(); |
93 | |
94 | min = (ktime_t)S64_MAX; |
95 | for (i = 0; i < 3; i++) { |
96 | start = ktime_get(); |
97 | for (j = 0; j < REPS; j++) { |
98 | mb(); /* prevent loop optimization */ |
99 | tmpl->do_2(BENCH_SIZE, b1, b2); |
100 | mb(); |
101 | } |
102 | diff = ktime_sub(ktime_get(), start); |
103 | if (diff < min) |
104 | min = diff; |
105 | } |
106 | |
107 | preempt_enable(); |
108 | |
109 | // bytes/ns == GB/s, multiply by 1000 to get MB/s [not MiB/s] |
110 | if (!min) |
111 | min = 1; |
112 | speed = (1000 * REPS * BENCH_SIZE) / (unsigned int)ktime_to_ns(kt: min); |
113 | tmpl->speed = speed; |
114 | |
115 | pr_info(" %-16s: %5d MB/sec\n" , tmpl->name, speed); |
116 | } |
117 | |
118 | static int __init |
119 | calibrate_xor_blocks(void) |
120 | { |
121 | void *b1, *b2; |
122 | struct xor_block_template *f, *fastest; |
123 | |
124 | fastest = XOR_SELECT_TEMPLATE(NULL); |
125 | |
126 | if (fastest) { |
127 | printk(KERN_INFO "xor: automatically using best " |
128 | "checksumming function %-10s\n" , |
129 | fastest->name); |
130 | goto out; |
131 | } |
132 | |
133 | b1 = (void *) __get_free_pages(GFP_KERNEL, order: 2); |
134 | if (!b1) { |
135 | printk(KERN_WARNING "xor: Yikes! No memory available.\n" ); |
136 | return -ENOMEM; |
137 | } |
138 | b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE; |
139 | |
140 | /* |
141 | * If this arch/cpu has a short-circuited selection, don't loop through |
142 | * all the possible functions, just test the best one |
143 | */ |
144 | |
145 | #define xor_speed(templ) do_xor_speed((templ), b1, b2) |
146 | |
147 | printk(KERN_INFO "xor: measuring software checksum speed\n" ); |
148 | template_list = NULL; |
149 | XOR_TRY_TEMPLATES; |
150 | fastest = template_list; |
151 | for (f = fastest; f; f = f->next) |
152 | if (f->speed > fastest->speed) |
153 | fastest = f; |
154 | |
155 | pr_info("xor: using function: %s (%d MB/sec)\n" , |
156 | fastest->name, fastest->speed); |
157 | |
158 | #undef xor_speed |
159 | |
160 | free_pages(addr: (unsigned long)b1, order: 2); |
161 | out: |
162 | active_template = fastest; |
163 | return 0; |
164 | } |
165 | |
166 | static __exit void xor_exit(void) { } |
167 | |
168 | MODULE_LICENSE("GPL" ); |
169 | |
170 | #ifndef MODULE |
171 | /* when built-in xor.o must initialize before drivers/md/md.o */ |
172 | core_initcall(register_xor_blocks); |
173 | #endif |
174 | |
175 | module_init(calibrate_xor_blocks); |
176 | module_exit(xor_exit); |
177 | |