/* -*- 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. * * ----------------------------------------------------------------------- */ /* * raid6/algos.c * * Algorithm list and algorithm selection for RAID-6 */ #include <linux/raid/pq.h>#ifndef __KERNEL__#include <sys/mman.h>#include <stdio.h>#else#include <linux/gfp.h>#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");