177 lines
3.8 KiB
C
177 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* xor.c : Multiple Devices driver for Linux
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*
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* Copyright (C) 1996, 1997, 1998, 1999, 2000,
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* Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson.
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*
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* Dispatch optimized RAID-5 checksumming functions.
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*/
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#define BH_TRACE 0
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#include <linux/module.h>
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#include <linux/gfp.h>
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#include <linux/raid/xor.h>
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#include <linux/jiffies.h>
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#include <linux/preempt.h>
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#include <asm/xor.h>
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#ifndef XOR_SELECT_TEMPLATE
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#define XOR_SELECT_TEMPLATE(x) (x)
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#endif
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/* The xor routines to use. */
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static struct xor_block_template *active_template;
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void
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xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs)
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{
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unsigned long *p1, *p2, *p3, *p4;
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p1 = (unsigned long *) srcs[0];
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if (src_count == 1) {
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active_template->do_2(bytes, dest, p1);
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return;
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}
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p2 = (unsigned long *) srcs[1];
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if (src_count == 2) {
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active_template->do_3(bytes, dest, p1, p2);
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return;
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}
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p3 = (unsigned long *) srcs[2];
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if (src_count == 3) {
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active_template->do_4(bytes, dest, p1, p2, p3);
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return;
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}
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p4 = (unsigned long *) srcs[3];
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active_template->do_5(bytes, dest, p1, p2, p3, p4);
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}
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EXPORT_SYMBOL(xor_blocks);
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/* Set of all registered templates. */
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static struct xor_block_template *__initdata template_list;
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#ifndef MODULE
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static void __init do_xor_register(struct xor_block_template *tmpl)
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{
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tmpl->next = template_list;
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template_list = tmpl;
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}
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static int __init register_xor_blocks(void)
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{
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active_template = XOR_SELECT_TEMPLATE(NULL);
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if (!active_template) {
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#define xor_speed do_xor_register
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// register all the templates and pick the first as the default
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XOR_TRY_TEMPLATES;
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#undef xor_speed
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active_template = template_list;
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}
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return 0;
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}
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#endif
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#define BENCH_SIZE 4096
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#define REPS 800U
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static void __init
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do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
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{
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int speed;
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int i, j;
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ktime_t min, start, diff;
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tmpl->next = template_list;
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template_list = tmpl;
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preempt_disable();
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min = (ktime_t)S64_MAX;
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for (i = 0; i < 3; i++) {
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start = ktime_get();
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for (j = 0; j < REPS; j++) {
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mb(); /* prevent loop optimization */
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tmpl->do_2(BENCH_SIZE, b1, b2);
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mb();
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}
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diff = ktime_sub(ktime_get(), start);
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if (diff < min)
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min = diff;
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}
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preempt_enable();
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// bytes/ns == GB/s, multiply by 1000 to get MB/s [not MiB/s]
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if (!min)
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min = 1;
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speed = (1000 * REPS * BENCH_SIZE) / (unsigned int)ktime_to_ns(min);
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tmpl->speed = speed;
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pr_info(" %-16s: %5d MB/sec\n", tmpl->name, speed);
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}
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static int __init
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calibrate_xor_blocks(void)
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{
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void *b1, *b2;
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struct xor_block_template *f, *fastest;
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fastest = XOR_SELECT_TEMPLATE(NULL);
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if (fastest) {
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printk(KERN_INFO "xor: automatically using best "
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"checksumming function %-10s\n",
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fastest->name);
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goto out;
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}
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b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
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if (!b1) {
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printk(KERN_WARNING "xor: Yikes! No memory available.\n");
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return -ENOMEM;
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}
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b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
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/*
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* If this arch/cpu has a short-circuited selection, don't loop through
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* all the possible functions, just test the best one
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*/
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#define xor_speed(templ) do_xor_speed((templ), b1, b2)
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printk(KERN_INFO "xor: measuring software checksum speed\n");
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template_list = NULL;
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XOR_TRY_TEMPLATES;
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fastest = template_list;
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for (f = fastest; f; f = f->next)
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if (f->speed > fastest->speed)
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fastest = f;
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pr_info("xor: using function: %s (%d MB/sec)\n",
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fastest->name, fastest->speed);
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#undef xor_speed
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free_pages((unsigned long)b1, 2);
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out:
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active_template = fastest;
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return 0;
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}
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static __exit void xor_exit(void) { }
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MODULE_LICENSE("GPL");
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#ifndef MODULE
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/* when built-in xor.o must initialize before drivers/md/md.o */
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core_initcall(register_xor_blocks);
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#endif
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module_init(calibrate_xor_blocks);
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module_exit(xor_exit);
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