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tag: v2.6.23-rc6
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/*
* xor.c : Multiple Devices driver for Linux
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000,
* Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson.
*
* Dispatch optimized RAID-5 checksumming functions.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* You should have received a copy of the GNU General Public License
* (for example /usr/src/linux/COPYING); if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#define BH_TRACE 0
#include <linux/module.h>
#include <linux/raid/md.h>
#include <linux/raid/xor.h>
#include <asm/xor.h>

/* The xor routines to use. */
static struct xor_block_template *active_template;

void
xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs)
{
unsigned long *p1, *p2, *p3, *p4;

p1 = (unsigned long *) srcs[0];
if (src_count == 1) {
active_template->do_2(bytes, dest, p1);
return;
}

p2 = (unsigned long *) srcs[1];
if (src_count == 2) {
active_template->do_3(bytes, dest, p1, p2);
return;
}

p3 = (unsigned long *) srcs[2];
if (src_count == 3) {
active_template->do_4(bytes, dest, p1, p2, p3);
return;
}

p4 = (unsigned long *) srcs[3];
active_template->do_5(bytes, dest, p1, p2, p3, p4);
}
EXPORT_SYMBOL(xor_blocks);

/* Set of all registered templates. */
static struct xor_block_template *template_list;

#define BENCH_SIZE (PAGE_SIZE)

static void
do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
{
int speed;
unsigned long now;
int i, count, max;

tmpl->next = template_list;
template_list = tmpl;

/*
* Count the number of XORs done during a whole jiffy, and use
* this to calculate the speed of checksumming. We use a 2-page
* allocation to have guaranteed color L1-cache layout.
*/
max = 0;
for (i = 0; i < 5; i++) {
now = jiffies;
count = 0;
while (jiffies == now) {
mb(); /* prevent loop optimzation */
tmpl->do_2(BENCH_SIZE, b1, b2);
mb();
count++;
mb();
}
if (count > max)
max = count;
}

speed = max * (HZ * BENCH_SIZE / 1024);
tmpl->speed = speed;

printk(KERN_INFO " %-10s: %5d.%03d MB/sec\n", tmpl->name,
speed / 1000, speed % 1000);
}

static int __init
calibrate_xor_blocks(void)
{
void *b1, *b2;
struct xor_block_template *f, *fastest;

b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
if (!b1) {
printk(KERN_WARNING "xor: Yikes! No memory available.\n");
return -ENOMEM;
}
b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;

/*
* If this arch/cpu has a short-circuited selection, don't loop through
* all the possible functions, just test the best one
*/

fastest = NULL;

#ifdef XOR_SELECT_TEMPLATE
fastest = XOR_SELECT_TEMPLATE(fastest);
#endif

#define xor_speed(templ) do_xor_speed((templ), b1, b2)

if (fastest) {
printk(KERN_INFO "xor: automatically using best "
"checksumming function: %s\n",
fastest->name);
xor_speed(fastest);
} else {
printk(KERN_INFO "xor: measuring software checksum speed\n");
XOR_TRY_TEMPLATES;
fastest = template_list;
for (f = fastest; f; f = f->next)
if (f->speed > fastest->speed)
fastest = f;
}

printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n",
fastest->name, fastest->speed / 1000, fastest->speed % 1000);

#undef xor_speed

free_pages((unsigned long)b1, 2);

active_template = fastest;
return 0;
}

static __exit void xor_exit(void) { }

MODULE_LICENSE("GPL");

/* when built-in xor.o must initialize before drivers/md/md.o */
core_initcall(calibrate_xor_blocks);
module_exit(xor_exit);
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