From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001
From: Linus Torvalds
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/xor.c | 154 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)
 create mode 100644 drivers/md/xor.c

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

diff --git a/drivers/md/xor.c b/drivers/md/xor.c
new file mode 100644
index 000000000000..324897c4be4e
--- /dev/null
+++ b/drivers/md/xor.c
@@ -0,0 +1,154 @@
+/*
+ * xor.c : Multiple Devices driver for Linux
+ *
+ * Copyright (C) 1996, 1997, 1998, 1999, 2000,
+ * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson.
+ *
+ * Dispatch optimized RAID-5 checksumming functions.
+ *
+ * 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; either version 2, or (at your option)
+ * any later version.
+ *
+ * You should have received a copy of the GNU General Public License
+ * (for example /usr/src/linux/COPYING); if not, write to the Free
+ * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#define BH_TRACE 0
+#include <linux/module.h>
+#include <linux/raid/md.h>
+#include <linux/raid/xor.h>
+#include <asm/xor.h>
+
+/* The xor routines to use.  */
+static struct xor_block_template *active_template;
+
+void
+xor_block(unsigned int count, unsigned int bytes, void **ptr)
+{
+	unsigned long *p0, *p1, *p2, *p3, *p4;
+
+	p0 = (unsigned long *) ptr[0];
+	p1 = (unsigned long *) ptr[1];
+	if (count == 2) {
+		active_template->do_2(bytes, p0, p1);
+		return;
+	}
+
+	p2 = (unsigned long *) ptr[2];
+	if (count == 3) {
+		active_template->do_3(bytes, p0, p1, p2);
+		return;
+	}
+
+	p3 = (unsigned long *) ptr[3];
+	if (count == 4) {
+		active_template->do_4(bytes, p0, p1, p2, p3);
+		return;
+	}
+
+	p4 = (unsigned long *) ptr[4];
+	active_template->do_5(bytes, p0, p1, p2, p3, p4);
+}
+
+/* Set of all registered templates.  */
+static struct xor_block_template *template_list;
+
+#define BENCH_SIZE (PAGE_SIZE)
+
+static void
+do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
+{
+	int speed;
+	unsigned long now;
+	int i, count, max;
+
+	tmpl->next = template_list;
+	template_list = tmpl;
+
+	/*
+	 * Count the number of XORs done during a whole jiffy, and use
+	 * this to calculate the speed of checksumming.  We use a 2-page
+	 * allocation to have guaranteed color L1-cache layout.
+	 */
+	max = 0;
+	for (i = 0; i < 5; i++) {
+		now = jiffies;
+		count = 0;
+		while (jiffies == now) {
+			mb();
+			tmpl->do_2(BENCH_SIZE, b1, b2);
+			mb();
+			count++;
+			mb();
+		}
+		if (count > max)
+			max = count;
+	}
+
+	speed = max * (HZ * BENCH_SIZE / 1024);
+	tmpl->speed = speed;
+
+	printk("   %-10s: %5d.%03d MB/sec\n", tmpl->name,
+	       speed / 1000, speed % 1000);
+}
+
+static int
+calibrate_xor_block(void)
+{
+	void *b1, *b2;
+	struct xor_block_template *f, *fastest;
+
+	b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
+	if (! b1) {
+		printk("raid5: Yikes!  No memory available.\n");
+		return -ENOMEM;
+	}
+	b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
+
+	/*
+	 * If this arch/cpu has a short-circuited selection, don't loop through all
+	 * the possible functions, just test the best one
+	 */
+
+	fastest = NULL;
+
+#ifdef XOR_SELECT_TEMPLATE
+		fastest = XOR_SELECT_TEMPLATE(fastest);
+#endif
+
+#define xor_speed(templ)	do_xor_speed((templ), b1, b2)
+
+	if (fastest) {
+		printk(KERN_INFO "raid5: automatically using best checksumming function: %s\n",
+			fastest->name);
+		xor_speed(fastest);
+	} else {
+		printk(KERN_INFO "raid5: measuring checksumming speed\n");
+		XOR_TRY_TEMPLATES;
+		fastest = template_list;
+		for (f = fastest; f; f = f->next)
+			if (f->speed > fastest->speed)
+				fastest = f;
+	}
+
+	printk("raid5: using function: %s (%d.%03d MB/sec)\n",
+	       fastest->name, fastest->speed / 1000, fastest->speed % 1000);
+
+#undef xor_speed
+
+	free_pages((unsigned long)b1, 2);
+
+	active_template = fastest;
+	return 0;
+}
+
+static __exit void xor_exit(void) { }
+
+EXPORT_SYMBOL(xor_block);
+MODULE_LICENSE("GPL");
+
+module_init(calibrate_xor_block);
+module_exit(xor_exit);
-- 
cgit v1.2.3-55-g7522