[linux-2.6-block.git] / drivers / md / raid6algos.c

/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright 2002 H. Peter Anvin - All Rights Reserved
 *
 *   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, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * raid6algos.c
 *
 * Algorithm list and algorithm selection for RAID-6
 */

#include <linux/raid/pq.h>
#include <linux/gfp.h>
#ifndef __KERNEL__
#include <sys/mman.h>
#include <stdio.h>
#else
#if !RAID6_USE_EMPTY_ZERO_PAGE
/* In .bss so it's zeroed */
const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
EXPORT_SYMBOL(raid6_empty_zero_page);
#endif
#endif

struct raid6_calls raid6_call;
EXPORT_SYMBOL_GPL(raid6_call);

const struct raid6_calls * const raid6_algos[] = {
	&raid6_intx1,
	&raid6_intx2,
	&raid6_intx4,
	&raid6_intx8,
#if defined(__ia64__)
	&raid6_intx16,
	&raid6_intx32,
#endif
#if defined(__i386__) && !defined(__arch_um__)
	&raid6_mmxx1,
	&raid6_mmxx2,
	&raid6_sse1x1,
	&raid6_sse1x2,
	&raid6_sse2x1,
	&raid6_sse2x2,
#endif
#if defined(__x86_64__) && !defined(__arch_um__)
	&raid6_sse2x1,
	&raid6_sse2x2,
	&raid6_sse2x4,
#endif
#ifdef CONFIG_ALTIVEC
	&raid6_altivec1,
	&raid6_altivec2,
	&raid6_altivec4,
	&raid6_altivec8,
#endif
	NULL
};

#ifdef __KERNEL__
#define RAID6_TIME_JIFFIES_LG2	4
#else
/* Need more time to be stable in userspace */
#define RAID6_TIME_JIFFIES_LG2	9
#define time_before(x, y) ((x) < (y))
#endif

/* Try to pick the best algorithm */
/* This code uses the gfmul table as convenient data set to abuse */

int __init raid6_select_algo(void)
{
	const struct raid6_calls * const * algo;
	const struct raid6_calls * best;
	char *syndromes;
	void *dptrs[(65536/PAGE_SIZE)+2];
	int i, disks;
	unsigned long perf, bestperf;
	int bestprefer;
	unsigned long j0, j1;

	disks = (65536/PAGE_SIZE)+2;
	for ( i = 0 ; i < disks-2 ; i++ ) {
		dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
	}

	/* Normal code - use a 2-page allocation to avoid D$ conflict */
	syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);

	if ( !syndromes ) {
		printk("raid6: Yikes!  No memory available.\n");
		return -ENOMEM;
	}

	dptrs[disks-2] = syndromes;
	dptrs[disks-1] = syndromes + PAGE_SIZE;

	bestperf = 0;  bestprefer = 0;  best = NULL;

	for ( algo = raid6_algos ; *algo ; algo++ ) {
		if ( !(*algo)->valid || (*algo)->valid() ) {
			perf = 0;

			preempt_disable();
			j0 = jiffies;
			while ( (j1 = jiffies) == j0 )
				cpu_relax();
			while (time_before(jiffies,
					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
				(*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
				perf++;
			}
			preempt_enable();

			if ( (*algo)->prefer > bestprefer ||
			     ((*algo)->prefer == bestprefer &&
			      perf > bestperf) ) {
				best = *algo;
				bestprefer = best->prefer;
				bestperf = perf;
			}
			printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
			       (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
		}
	}

	if (best) {
		printk("raid6: using algorithm %s (%ld MB/s)\n",
		       best->name,
		       (bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
		raid6_call = *best;
	} else
		printk("raid6: Yikes!  No algorithm found!\n");

	free_pages((unsigned long)syndromes, 1);

	return best ? 0 : -EINVAL;
}

static void raid6_exit(void)
{
	do { } while (0);
}

subsys_initcall(raid6_select_algo);
module_exit(raid6_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
Commit	Line	Data
1da177e4 LT	1	/* -- linux-c -- ------------------------------------------------------- *
	2	*
	3	* Copyright 2002 H. Peter Anvin - All Rights Reserved
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation, Inc., 53 Temple Place Ste 330,
93ed05e2	8	* Boston MA 02111-1307, USA; either version 2 of the License, or
1da177e4 LT	9	* (at your option) any later version; incorporated herein by reference.
	10	*
	11	* ----------------------------------------------------------------------- */
	12
	13	/*
	14	* raid6algos.c
	15	*
	16	* Algorithm list and algorithm selection for RAID-6
	17	*/
	18
f701d589	19	#include <linux/raid/pq.h>
5a0e3ad6	20	#include <linux/gfp.h>
1da177e4 LT	21	#ifndef __KERNEL__
1da177e4 LT	22	#include <sys/mman.h>
d7e70ba4	23	#include <stdio.h>
f701d589 DW	24	#else
	25	#if !RAID6_USE_EMPTY_ZERO_PAGE
	26	/* In .bss so it's zeroed */
	27	const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
	28	EXPORT_SYMBOL(raid6_empty_zero_page);
	29	#endif
1da177e4 LT	30	#endif
	31
	32	struct raid6_calls raid6_call;
f701d589	33	EXPORT_SYMBOL_GPL(raid6_call);
1da177e4	34
1da177e4 LT	35	const struct raid6_calls * const raid6_algos[] = {
	36	&raid6_intx1,
	37	&raid6_intx2,
	38	&raid6_intx4,
	39	&raid6_intx8,
	40	#if defined(__ia64__)
	41	&raid6_intx16,
	42	&raid6_intx32,
	43	#endif
ca5cd877	44	#if defined(__i386__) && !defined(__arch_um__)
1da177e4 LT	45	&raid6_mmxx1,
	46	&raid6_mmxx2,
	47	&raid6_sse1x1,
	48	&raid6_sse1x2,
	49	&raid6_sse2x1,
	50	&raid6_sse2x2,
	51	#endif
ca5cd877	52	#if defined(__x86_64__) && !defined(__arch_um__)
1da177e4 LT	53	&raid6_sse2x1,
	54	&raid6_sse2x2,
	55	&raid6_sse2x4,
	56	#endif
	57	#ifdef CONFIG_ALTIVEC
	58	&raid6_altivec1,
	59	&raid6_altivec2,
	60	&raid6_altivec4,
	61	&raid6_altivec8,
	62	#endif
	63	NULL
	64	};
	65
	66	#ifdef __KERNEL__
	67	#define RAID6_TIME_JIFFIES_LG2 4
	68	#else
	69	/* Need more time to be stable in userspace */
	70	#define RAID6_TIME_JIFFIES_LG2 9
f701d589	71	#define time_before(x, y) ((x) < (y))
1da177e4 LT	72	#endif
	73
	74	/* Try to pick the best algorithm */
	75	/* This code uses the gfmul table as convenient data set to abuse */
	76
	77	int __init raid6_select_algo(void)
	78	{
	79	const struct raid6_calls * const * algo;
	80	const struct raid6_calls * best;
	81	char *syndromes;
	82	void *dptrs[(65536/PAGE_SIZE)+2];
	83	int i, disks;
	84	unsigned long perf, bestperf;
	85	int bestprefer;
	86	unsigned long j0, j1;
	87
	88	disks = (65536/PAGE_SIZE)+2;
	89	for ( i = 0 ; i < disks-2 ; i++ ) {
	90	dptrs[i] = ((char )raid6_gfmul) + PAGE_SIZEi;
	91	}
	92
	93	/* Normal code - use a 2-page allocation to avoid D$ conflict */
	94	syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
	95
	96	if ( !syndromes ) {
	97	printk("raid6: Yikes! No memory available.\n");
	98	return -ENOMEM;
	99	}
	100
	101	dptrs[disks-2] = syndromes;
	102	dptrs[disks-1] = syndromes + PAGE_SIZE;
	103
	104	bestperf = 0; bestprefer = 0; best = NULL;
	105
	106	for ( algo = raid6_algos ; *algo ; algo++ ) {
	107	if ( !(algo)->valid \|\| (algo)->valid() ) {
	108	perf = 0;
	109
	110	preempt_disable();
	111	j0 = jiffies;
	112	while ( (j1 = jiffies) == j0 )
	113	cpu_relax();
62b0559a JL	114	while (time_before(jiffies,
62b0559a JL	115	j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
1da177e4 LT	116	(*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
	117	perf++;
	118	}
	119	preempt_enable();
	120
	121	if ( (*algo)->prefer > bestprefer \|\|
	122	((*algo)->prefer == bestprefer &&
	123	perf > bestperf) ) {
	124	best = *algo;
	125	bestprefer = best->prefer;
	126	bestperf = perf;
	127	}
	128	printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
	129	(perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
	130	}
	131	}
	132
a5d6839b	133	if (best) {
1da177e4 LT	134	printk("raid6: using algorithm %s (%ld MB/s)\n",
	135	best->name,
	136	(bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
a5d6839b AB	137	raid6_call = *best;
a5d6839b AB	138	} else
1da177e4 LT	139	printk("raid6: Yikes! No algorithm found!\n");
1da177e4 LT	140
1da177e4 LT	141	free_pages((unsigned long)syndromes, 1);
	142
	143	return best ? 0 : -EINVAL;
	144	}
f701d589 DW	145
	146	static void raid6_exit(void)
	147	{
	148	do { } while (0);
	149	}
	150
	151	subsys_initcall(raid6_select_algo);
	152	module_exit(raid6_exit);
	153	MODULE_LICENSE("GPL");
0efb9e61	154	MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");