1/*
2 * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28/*
29 * @OSF_COPYRIGHT@
30 */
31/*
32 * Mach Operating System
33 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
34 * All Rights Reserved.
35 *
36 * Permission to use, copy, modify and distribute this software and its
37 * documentation is hereby granted, provided that both the copyright
38 * notice and this permission notice appear in all copies of the
39 * software, derivative works or modified versions, and any portions
40 * thereof, and that both notices appear in supporting documentation.
41 *
42 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
43 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
44 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
45 *
46 * Carnegie Mellon requests users of this software to return to
47 *
48 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
49 * School of Computer Science
50 * Carnegie Mellon University
51 * Pittsburgh PA 15213-3890
52 *
53 * any improvements or extensions that they make and grant Carnegie Mellon
54 * the rights to redistribute these changes.
55 */
56/*
57 */
58
59#ifndef _KERN_TIMER_H_
60#define _KERN_TIMER_H_
61
62#include <kern/kern_types.h>
63
64/*
65 * Some platforms have very expensive timebase routines. An optimization
66 * is to avoid switching timers on kernel exit/entry, which results in all
67 * time billed to the system timer. However, when exposed to userspace,
68 * we report as user time to indicate that work was done on behalf of
69 * userspace.
70 *
71 * Although this policy is implemented as a global variable, we snapshot it
72 * at key points in the thread structure (when the thread is locked and
73 * executing in the kernel) to avoid imbalances.
74 */
75extern int precise_user_kernel_time;
76
77/*
78 * thread must be locked, or be the current executing thread, so that
79 * it doesn't transition from user to kernel while updating the
80 * thread-local value (or in kernel debugger context). In the future,
81 * we make take into account task-level or thread-level policy.
82 */
83#define use_precise_user_kernel_time(thread) (precise_user_kernel_time)
84
85/*
86 * Definitions for high resolution timers.
87 */
88
89struct timer {
90 uint64_t tstamp;
91#if defined(__LP64__)
92 uint64_t all_bits;
93#else /* defined(__LP64__) */
94 /* A check word on the high portion allows atomic updates. */
95 uint32_t low_bits;
96 uint32_t high_bits;
97 uint32_t high_bits_check;
98#endif /* !defined(__LP64__) */
99};
100
101typedef struct timer timer_data_t, *timer_t;
102
103/*
104 * Initialize the `timer`.
105 */
106void timer_init(timer_t timer);
107
108/*
109 * Start the `timer` at time `tstamp`.
110 */
111void timer_start(timer_t timer, uint64_t tstamp);
112
113/*
114 * Stop the `timer` and update it with time `tstamp`.
115 */
116void timer_stop(timer_t timer, uint64_t tstamp);
117
118/*
119 * Update the `timer` at time `tstamp`, leaving it running.
120 */
121void timer_update(timer_t timer, uint64_t tstamp);
122
123/*
124 * Update the `timer` with time `tstamp` and start `new_timer`.
125 */
126void timer_switch(timer_t timer, uint64_t tstamp, timer_t new_timer);
127
128/*
129 * Update the thread timer at an "event," like a context switch, at time
130 * `tstamp`. This stops the current timer and starts the `new_timer` running.
131 *
132 * Must be called with interrupts disabled.
133 */
134void processor_timer_switch_thread(uint64_t tstamp, timer_t new_timer);
135
136/*
137 * Return the difference between the `timer` and a previous value pointed to by
138 * `prev_in_cur_out`. Store the current value of the timer to
139 * `prev_in_cur_out`.
140 */
141uint64_t timer_delta(timer_t timer, uint64_t *prev_in_cur_out);
142
143/*
144 * Read the accumulated time of `timer`.
145 */
146#if defined(__LP64__)
147static inline
148uint64_t
149timer_grab(timer_t timer)
150{
151 return timer->all_bits;
152}
153#else /* defined(__LP64__) */
154uint64_t timer_grab(timer_t timer);
155#endif /* !defined(__LP64__) */
156
157#endif /* _KERN_TIMER_H_ */
158