1/*
2 * Copyright (c) 2000-2007 Apple Computer, 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
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20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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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 *	Author:	Avadis Tevanian, Jr.
60 *	Date:	1986
61 *
62 *	Compute various averages.
63 */
64
65#include <mach/mach_types.h>
66
67#include <kern/sched.h>
68#include <kern/assert.h>
69#include <kern/processor.h>
70#include <kern/thread.h>
71
72uint32_t	avenrun[3] = {0, 0, 0};
73uint32_t	mach_factor[3] = {0, 0, 0};
74
75/*
76 * Values are scaled by LOAD_SCALE, defined in processor_info.h
77 */
78#define base(n)		((n) << SCHED_TICK_SHIFT)
79#define frac(n)		(((base(n) - 1) * LOAD_SCALE) /	base(n))
80
81static uint32_t		fract[3] = {
82	frac(5),		/* 5 second average */
83	frac(30),		/* 30 second average */
84	frac(60),		/* 1 minute average */
85};
86
87#undef base
88#undef frac
89
90static unsigned int		sched_nrun;
91
92typedef void	(*sched_avg_comp_t)(
93					void			*param);
94
95#define SCHED_AVG_SECS(n)	((n) << SCHED_TICK_SHIFT)
96
97static struct sched_average {
98	sched_avg_comp_t	comp;
99	void				*param;
100	int					period;
101	int					tick;
102} sched_average[] = {
103	{ compute_averunnable, &sched_nrun, SCHED_AVG_SECS(5), 0 },
104	{ compute_stack_target, NULL, SCHED_AVG_SECS(5), 1 },
105	{ NULL, NULL, 0, 0 }
106};
107
108typedef struct sched_average	*sched_average_t;
109
110void
111compute_averages(void)
112{
113	int					ncpus, nthreads, nshared;
114	uint32_t			factor_now, average_now, load_now = 0;
115	sched_average_t		avg;
116
117	/*
118	 *	Retrieve counts, ignoring
119	 *	the current thread.
120	 */
121	ncpus = processor_avail_count;
122	nthreads = sched_run_count - 1;
123	nshared = sched_share_count;
124
125	/*
126	 *	Load average and mach factor calculations for
127	 *	those which ask about these things.
128	 */
129	average_now = nthreads * LOAD_SCALE;
130
131	if (nthreads > ncpus)
132		factor_now = (ncpus * LOAD_SCALE) / (nthreads + 1);
133	else
134		factor_now = (ncpus - nthreads) * LOAD_SCALE;
135
136	sched_mach_factor =	((sched_mach_factor << 2) + factor_now) / 5;
137	sched_load_average = ((sched_load_average << 2) + average_now) / 5;
138
139	/*
140	 *	Compute the timeshare priority
141	 *	conversion factor based on loading.
142	 */
143	if (nshared > nthreads)
144		nshared = nthreads;
145
146	if (nshared > ncpus) {
147		if (ncpus > 1)
148			load_now = nshared / ncpus;
149		else
150			load_now = nshared;
151
152		if (load_now > NRQS - 1)
153			load_now = NRQS - 1;
154	}
155
156	/*
157	 *	The conversion factor consists of
158	 *	two components: a fixed value based
159	 *	on the absolute time unit, and a
160	 *	dynamic portion based on loading.
161	 *
162	 *	Zero loading results in a out of range
163	 *	shift count.  Accumulated usage is ignored
164	 *	during conversion and new usage deltas
165	 *	are discarded.
166	 */
167	sched_pri_shift = sched_fixed_shift - sched_load_shifts[load_now];
168
169	/*
170	 *	Sample total running threads.
171	 */
172	sched_nrun = nthreads;
173
174	/*
175	 * Compute old-style Mach load averages.
176	 */
177	{
178		register int		i;
179
180		for (i = 0; i < 3; i++) {
181			mach_factor[i] = ((mach_factor[i] * fract[i]) +
182						(factor_now * (LOAD_SCALE - fract[i]))) / LOAD_SCALE;
183
184			avenrun[i] = ((avenrun[i] * fract[i]) +
185						(average_now * (LOAD_SCALE - fract[i]))) / LOAD_SCALE;
186		}
187	}
188
189	/*
190	 *	Compute averages in other components.
191	 */
192	for (avg = sched_average; avg->comp != NULL; ++avg) {
193		if (++avg->tick >= avg->period) {
194			(*avg->comp)(avg->param);
195			avg->tick = 0;
196		}
197	}
198}
199