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
);
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