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Diffstat (limited to 'lib/raid6/algos.c')
| -rw-r--r-- | lib/raid6/algos.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c new file mode 100644 index 00000000..8b02f60f --- /dev/null +++ b/lib/raid6/algos.c @@ -0,0 +1,155 @@ +/* -*- 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> +#include <linux/module.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"); |