mirror of
https://github.com/torvalds/linux.git
synced 2024-11-17 17:41:44 +00:00
155 lines
3.6 KiB
C
155 lines
3.6 KiB
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");
|