crypto/xor.c

   1 /*
   2  * xor.c : Multiple Devices driver for Linux
   3  *
   4  * Copyright (C) 1996, 1997, 1998, 1999, 2000,
   5  * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson.
   6  *
   7  * Dispatch optimized RAID-5 checksumming functions.
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2, or (at your option)
  12  * any later version.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * (for example /usr/src/linux/COPYING); if not, write to the Free
  16  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #define BH_TRACE 0
  20 #include <linux/module.h>
  21 #include <linux/gfp.h>
  22 #include <linux/raid/xor.h>
  23 #include <linux/jiffies.h>
  24 #include <linux/preempt.h>
  25 #include <asm/xor.h>
  26
  27 /* The xor routines to use.  */
  28 static struct xor_block_template *active_template;
  29
  30 void
  31 xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs)
  32 {
  33         unsigned long *p1, *p2, *p3, *p4;
  34
  35         p1 = (unsigned long *) srcs[0];
  36         if (src_count == 1) {
  37                 active_template->do_2(bytes, dest, p1);
  38                 return;
  39         }
  40
  41         p2 = (unsigned long *) srcs[1];
  42         if (src_count == 2) {
  43                 active_template->do_3(bytes, dest, p1, p2);
  44                 return;
  45         }
  46
  47         p3 = (unsigned long *) srcs[2];
  48         if (src_count == 3) {
  49                 active_template->do_4(bytes, dest, p1, p2, p3);
  50                 return;
  51         }
  52
  53         p4 = (unsigned long *) srcs[3];
  54         active_template->do_5(bytes, dest, p1, p2, p3, p4);
  55 }
  56 EXPORT_SYMBOL(xor_blocks);
  57
  58 /* Set of all registered templates.  */
  59 static struct xor_block_template *template_list;
  60
  61 #define BENCH_SIZE (PAGE_SIZE)
  62
  63 static void
  64 do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
  65 {
  66         int speed;
  67         unsigned long now, j;
  68         int i, count, max;
  69
  70         tmpl->next = template_list;
  71         template_list = tmpl;
  72
  73         preempt_disable();
  74
  75         /*
  76          * Count the number of XORs done during a whole jiffy, and use
  77          * this to calculate the speed of checksumming.  We use a 2-page
  78          * allocation to have guaranteed color L1-cache layout.
  79          */
  80         max = 0;
  81         for (i = 0; i < 5; i++) {
  82                 j = jiffies;
  83                 count = 0;
  84                 while ((now = jiffies) == j)
  85                         cpu_relax();
  86                 while (time_before(jiffies, now + 1)) {
  87                         mb(); /* prevent loop optimzation */
  88                         tmpl->do_2(BENCH_SIZE, b1, b2);
  89                         mb();
  90                         count++;
  91                         mb();
  92                 }
  93                 if (count > max)
  94                         max = count;
  95         }
  96
  97         preempt_enable();
  98
  99         speed = max * (HZ * BENCH_SIZE / 1024);
 100         tmpl->speed = speed;
 101
 102         printk(KERN_INFO "   %-10s: %5d.%03d MB/sec\n", tmpl->name,
 103                speed / 1000, speed % 1000);
 104 }
 105
 106 static int __init
 107 calibrate_xor_blocks(void)
 108 {
 109         void *b1, *b2;
 110         struct xor_block_template *f, *fastest;
 111
 112         /*
 113          * Note: Since the memory is not actually used for _anything_ but to
 114          * test the XOR speed, we don't really want kmemcheck to warn about
 115          * reading uninitialized bytes here.
 116          */
 117         b1 = (void *) __get_free_pages(GFP_KERNEL | __GFP_NOTRACK, 2);
 118         if (!b1) {
 119                 printk(KERN_WARNING "xor: Yikes!  No memory available.\n");
 120                 return -ENOMEM;
 121         }
 122         b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
 123
 124         /*
 125          * If this arch/cpu has a short-circuited selection, don't loop through
 126          * all the possible functions, just test the best one
 127          */
 128
 129         fastest = NULL;
 130
 131 #ifdef XOR_SELECT_TEMPLATE
 132                 fastest = XOR_SELECT_TEMPLATE(fastest);
 133 #endif
 134
 135 #define xor_speed(templ)        do_xor_speed((templ), b1, b2)
 136
 137         if (fastest) {
 138                 printk(KERN_INFO "xor: automatically using best "
 139                                  "checksumming function:\n");
 140                 xor_speed(fastest);
 141                 goto out;
 142         } else {
 143                 printk(KERN_INFO "xor: measuring software checksum speed\n");
 144                 XOR_TRY_TEMPLATES;
 145                 fastest = template_list;
 146                 for (f = fastest; f; f = f->next)
 147                         if (f->speed > fastest->speed)
 148                                 fastest = f;
 149         }
 150
 151         printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n",
 152                fastest->name, fastest->speed / 1000, fastest->speed % 1000);
 153
 154 #undef xor_speed
 155
 156  out:
 157         free_pages((unsigned long)b1, 2);
 158
 159         active_template = fastest;
 160         return 0;
 161 }
 162
 163 static __exit void xor_exit(void) { }
 164
 165 MODULE_LICENSE("GPL");
 166
 167 /* when built-in xor.o must initialize before drivers/md/md.o */
 168 core_initcall(calibrate_xor_blocks);
 169 module_exit(xor_exit);