diff options
Diffstat (limited to 'drivers/md/xor.c')
| -rw-r--r-- | drivers/md/xor.c | 154 |
1 files changed, 154 insertions, 0 deletions
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); |