From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Sat, 16 Apr 2005 15:20:36 -0700
Subject: Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
---
 drivers/md/raid6algos.c | 153 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 drivers/md/raid6algos.c

(limited to 'drivers/md/raid6algos.c')

diff --git a/drivers/md/raid6algos.c b/drivers/md/raid6algos.c
new file mode 100644
index 00000000000..acf386fc4b4
--- /dev/null
+++ b/drivers/md/raid6algos.c
@@ -0,0 +1,153 @@
+/* -*- 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,
+ *   Bostom 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 "raid6.h"
+#ifndef __KERNEL__
+#include <sys/mman.h>
+#endif
+
+struct raid6_calls raid6_call;
+
+/* Various routine sets */
+extern const struct raid6_calls raid6_intx1;
+extern const struct raid6_calls raid6_intx2;
+extern const struct raid6_calls raid6_intx4;
+extern const struct raid6_calls raid6_intx8;
+extern const struct raid6_calls raid6_intx16;
+extern const struct raid6_calls raid6_intx32;
+extern const struct raid6_calls raid6_mmxx1;
+extern const struct raid6_calls raid6_mmxx2;
+extern const struct raid6_calls raid6_sse1x1;
+extern const struct raid6_calls raid6_sse1x2;
+extern const struct raid6_calls raid6_sse2x1;
+extern const struct raid6_calls raid6_sse2x2;
+extern const struct raid6_calls raid6_sse2x4;
+extern const struct raid6_calls raid6_altivec1;
+extern const struct raid6_calls raid6_altivec2;
+extern const struct raid6_calls raid6_altivec4;
+extern const struct raid6_calls raid6_altivec8;
+
+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__)
+	&raid6_mmxx1,
+	&raid6_mmxx2,
+	&raid6_sse1x1,
+	&raid6_sse1x2,
+	&raid6_sse2x1,
+	&raid6_sse2x2,
+#endif
+#if defined(__x86_64__)
+	&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
+#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 ( (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));
+	else
+		printk("raid6: Yikes!  No algorithm found!\n");
+
+	raid6_call = *best;
+
+	free_pages((unsigned long)syndromes, 1);
+
+	return best ? 0 : -EINVAL;
+}
-- 
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