ksched.c revision 170307 
1/*-
2 * Copyright (c) 1996, 1997
3 *	HD Associates, Inc.  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 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by HD Associates, Inc
16 * 4. Neither the name of the author nor the names of any co-contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33/* ksched: Soft real time scheduling based on "rtprio".
34 */
35
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: head/sys/kern/ksched.c 170307 2007-06-05 00:00:57Z jeff $");
38
39#include "opt_posix.h"
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/lock.h>
44#include <sys/mutex.h>
45#include <sys/proc.h>
46#include <sys/posix4.h>
47#include <sys/resource.h>
48#include <sys/sched.h>
49
50/* ksched: Real-time extension to support POSIX priority scheduling.
51 */
52
53struct ksched {
54	struct timespec rr_interval;
55};
56
57int
58ksched_attach(struct ksched **p)
59{
60	struct ksched *ksched= p31b_malloc(sizeof(*ksched));
61
62	ksched->rr_interval.tv_sec = 0;
63	ksched->rr_interval.tv_nsec = 1000000000L / sched_rr_interval();
64
65	*p = ksched;
66	return 0;
67}
68
69int
70ksched_detach(struct ksched *ks)
71{
72	p31b_free(ks);
73
74	return 0;
75}
76
77/*
78 * XXX About priorities
79 *
80 *	POSIX 1003.1b requires that numerically higher priorities be of
81 *	higher priority.  It also permits sched_setparam to be
82 *	implementation defined for SCHED_OTHER.  I don't like
83 *	the notion of inverted priorites for normal processes when
84 *  you can use "setpriority" for that.
85 *
86 *	I'm rejecting sched_setparam for SCHED_OTHER with EINVAL.
87 */
88
89/* Macros to convert between the unix (lower numerically is higher priority)
90 * and POSIX 1003.1b (higher numerically is higher priority)
91 */
92
93#define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
94#define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
95
96/* These improve readability a bit for me:
97 */
98#define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
99#define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
100
101static __inline int
102getscheduler(struct ksched *ksched, struct thread *td, int *policy)
103{
104	struct rtprio rtp;
105	int e = 0;
106
107	pri_to_rtp(td, &rtp);
108	switch (rtp.type)
109	{
110		case RTP_PRIO_FIFO:
111		*policy = SCHED_FIFO;
112		break;
113
114		case RTP_PRIO_REALTIME:
115		*policy = SCHED_RR;
116		break;
117
118		default:
119		*policy = SCHED_OTHER;
120		break;
121	}
122
123	return e;
124}
125
126int
127ksched_setparam(struct ksched *ksched,
128    struct thread *td, const struct sched_param *param)
129{
130	int policy;
131	int e;
132
133	e = getscheduler(ksched, td, &policy);
134
135	if (e == 0)
136	{
137		if (policy == SCHED_OTHER)
138			e = EINVAL;
139		else
140			e = ksched_setscheduler(ksched, td, policy, param);
141	}
142
143	return e;
144}
145
146int
147ksched_getparam(struct ksched *ksched,
148    struct thread *td, struct sched_param *param)
149{
150	struct rtprio rtp;
151
152	pri_to_rtp(td, &rtp);
153	if (RTP_PRIO_IS_REALTIME(rtp.type))
154		param->sched_priority = rtpprio_to_p4prio(rtp.prio);
155
156	return 0;
157}
158
159/*
160 * XXX The priority and scheduler modifications should
161 *     be moved into published interfaces in kern/kern_sync.
162 *
163 * The permissions to modify process p were checked in "p31b_proc()".
164 *
165 */
166int
167ksched_setscheduler(struct ksched *ksched,
168    struct thread *td, int policy, const struct sched_param *param)
169{
170	int e = 0;
171	struct rtprio rtp;
172
173	switch(policy)
174	{
175		case SCHED_RR:
176		case SCHED_FIFO:
177
178		if (param->sched_priority >= P1B_PRIO_MIN &&
179		    param->sched_priority <= P1B_PRIO_MAX)
180		{
181			rtp.prio = p4prio_to_rtpprio(param->sched_priority);
182			rtp.type = (policy == SCHED_FIFO)
183				? RTP_PRIO_FIFO : RTP_PRIO_REALTIME;
184
185			rtp_to_pri(&rtp, td);
186		}
187		else
188			e = EPERM;
189
190
191		break;
192
193		case SCHED_OTHER:
194		{
195			rtp.type = RTP_PRIO_NORMAL;
196			rtp.prio = p4prio_to_rtpprio(param->sched_priority);
197			rtp_to_pri(&rtp, td);
198		}
199		break;
200
201		default:
202			e = EINVAL;
203			break;
204	}
205
206	return e;
207}
208
209int
210ksched_getscheduler(struct ksched *ksched, struct thread *td, int *policy)
211{
212	return getscheduler(ksched, td, policy);
213}
214
215/* ksched_yield: Yield the CPU.
216 */
217int
218ksched_yield(struct ksched *ksched)
219{
220	sched_relinquish(curthread);
221	return 0;
222}
223
224int
225ksched_get_priority_max(struct ksched *ksched, int policy, int *prio)
226{
227	int e = 0;
228
229	switch (policy)
230	{
231		case SCHED_FIFO:
232		case SCHED_RR:
233		*prio = RTP_PRIO_MAX;
234		break;
235
236		case SCHED_OTHER:
237		*prio = PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE;
238		break;
239
240		default:
241		e = EINVAL;
242	}
243
244	return e;
245}
246
247int
248ksched_get_priority_min(struct ksched *ksched, int policy, int *prio)
249{
250	int e = 0;
251
252	switch (policy)
253	{
254		case SCHED_FIFO:
255		case SCHED_RR:
256		*prio = P1B_PRIO_MIN;
257		break;
258
259		case SCHED_OTHER:
260		*prio = 0;
261		break;
262
263		default:
264		e = EINVAL;
265	}
266
267	return e;
268}
269
270int
271ksched_rr_get_interval(struct ksched *ksched,
272   struct thread *td, struct timespec *timespec)
273{
274	*timespec = ksched->rr_interval;
275
276	return 0;
277}
278