subr_counter.c revision 249590 
1/*-
2 * Copyright (c) 2012 Gleb Smirnoff <glebius@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/kern/subr_counter.c 249590 2013-04-17 18:43:33Z glebius $");
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/counter.h>
33#include <sys/kernel.h>
34#include <sys/smp.h>
35#include <sys/sysctl.h>
36#include <vm/uma.h>
37
38static uma_zone_t uint64_pcpu_zone;
39
40void
41counter_u64_zero(counter_u64_t c)
42{
43	int i;
44
45	for (i = 0; i < mp_ncpus; i++)
46		*(uint64_t *)((char *)c + sizeof(struct pcpu) * i) = 0;
47}
48
49uint64_t
50counter_u64_fetch(counter_u64_t c)
51{
52	uint64_t r;
53	int i;
54
55	r = 0;
56	for (i = 0; i < mp_ncpus; i++)
57		r += *(uint64_t *)((char *)c + sizeof(struct pcpu) * i);
58
59	return (r);
60}
61
62counter_u64_t
63counter_u64_alloc(int flags)
64{
65	counter_u64_t r;
66
67	r = uma_zalloc(uint64_pcpu_zone, flags);
68	if (r != NULL)
69		counter_u64_zero(r);
70
71	return (r);
72}
73
74void
75counter_u64_free(counter_u64_t c)
76{
77
78	uma_zfree(uint64_pcpu_zone, c);
79}
80
81int
82sysctl_handle_counter_u64(SYSCTL_HANDLER_ARGS)
83{
84	uint64_t out;
85	int error;
86
87	out = counter_u64_fetch(*(counter_u64_t *)arg1);
88
89	error = SYSCTL_OUT(req, &out, sizeof(uint64_t));
90
91	if (error || !req->newptr)
92		return (error);
93
94	/*
95	 * Any write attempt to a counter zeroes it.
96	 */
97	counter_u64_zero(*(counter_u64_t *)arg1);
98
99	return (0);
100}
101
102static void
103counter_startup(void)
104{
105
106	uint64_pcpu_zone = uma_zcreate("uint64 pcpu", sizeof(uint64_t),
107	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_PCPU);
108}
109SYSINIT(counter, SI_SUB_CPU, SI_ORDER_FOURTH, counter_startup, NULL);
110