156 lines
3.7 KiB
C
156 lines
3.7 KiB
C
/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright 2002 H. Peter Anvin - All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, Inc., 53 Temple Place Ste 330,
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* Boston MA 02111-1307, USA; either version 2 of the License, or
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* (at your option) any later version; incorporated herein by reference.
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*
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* ----------------------------------------------------------------------- */
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/*
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* raid6/algos.c
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*
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* Algorithm list and algorithm selection for RAID-6
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*/
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#include <linux/raid/pq.h>
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#include <linux/module.h>
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#ifndef __KERNEL__
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#include <sys/mman.h>
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#include <stdio.h>
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#else
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#include <linux/gfp.h>
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#if !RAID6_USE_EMPTY_ZERO_PAGE
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/* In .bss so it's zeroed */
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const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
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EXPORT_SYMBOL(raid6_empty_zero_page);
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#endif
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#endif
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struct raid6_calls raid6_call;
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EXPORT_SYMBOL_GPL(raid6_call);
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const struct raid6_calls * const raid6_algos[] = {
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&raid6_intx1,
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&raid6_intx2,
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&raid6_intx4,
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&raid6_intx8,
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#if defined(__ia64__)
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&raid6_intx16,
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&raid6_intx32,
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#endif
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#if defined(__i386__) && !defined(__arch_um__)
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&raid6_mmxx1,
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&raid6_mmxx2,
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&raid6_sse1x1,
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&raid6_sse1x2,
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&raid6_sse2x1,
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&raid6_sse2x2,
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#endif
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#if defined(__x86_64__) && !defined(__arch_um__)
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&raid6_sse2x1,
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&raid6_sse2x2,
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&raid6_sse2x4,
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#endif
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#ifdef CONFIG_ALTIVEC
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&raid6_altivec1,
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&raid6_altivec2,
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&raid6_altivec4,
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&raid6_altivec8,
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#endif
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NULL
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};
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#ifdef __KERNEL__
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#define RAID6_TIME_JIFFIES_LG2 4
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#else
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/* Need more time to be stable in userspace */
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#define RAID6_TIME_JIFFIES_LG2 9
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#define time_before(x, y) ((x) < (y))
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#endif
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/* Try to pick the best algorithm */
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/* This code uses the gfmul table as convenient data set to abuse */
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int __init raid6_select_algo(void)
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{
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const struct raid6_calls * const * algo;
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const struct raid6_calls * best;
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char *syndromes;
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void *dptrs[(65536/PAGE_SIZE)+2];
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int i, disks;
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unsigned long perf, bestperf;
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int bestprefer;
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unsigned long j0, j1;
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disks = (65536/PAGE_SIZE)+2;
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for ( i = 0 ; i < disks-2 ; i++ ) {
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dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
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}
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/* Normal code - use a 2-page allocation to avoid D$ conflict */
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syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
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if ( !syndromes ) {
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printk("raid6: Yikes! No memory available.\n");
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return -ENOMEM;
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}
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dptrs[disks-2] = syndromes;
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dptrs[disks-1] = syndromes + PAGE_SIZE;
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bestperf = 0; bestprefer = 0; best = NULL;
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for ( algo = raid6_algos ; *algo ; algo++ ) {
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if ( !(*algo)->valid || (*algo)->valid() ) {
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perf = 0;
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preempt_disable();
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j0 = jiffies;
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while ( (j1 = jiffies) == j0 )
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cpu_relax();
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while (time_before(jiffies,
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j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
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(*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
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perf++;
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}
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preempt_enable();
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if ( (*algo)->prefer > bestprefer ||
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((*algo)->prefer == bestprefer &&
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perf > bestperf) ) {
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best = *algo;
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bestprefer = best->prefer;
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bestperf = perf;
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}
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printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
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(perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
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}
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}
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if (best) {
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printk("raid6: using algorithm %s (%ld MB/s)\n",
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best->name,
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(bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
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raid6_call = *best;
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} else
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printk("raid6: Yikes! No algorithm found!\n");
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free_pages((unsigned long)syndromes, 1);
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return best ? 0 : -EINVAL;
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}
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static void raid6_exit(void)
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{
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do { } while (0);
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}
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subsys_initcall(raid6_select_algo);
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module_exit(raid6_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
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