FreeBSD/Linux Kernel Cross Reference
sys/kern/ksched.c
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: releng/8.0/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
53 struct ksched {
54 struct timespec rr_interval;
55 };
56
57 int
58 ksched_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
69 int
70 ksched_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
101 static __inline int
102 getscheduler(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
126 int
127 ksched_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
146 int
147 ksched_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 */
166 int
167 ksched_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
209 int
210 ksched_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 */
217 int
218 ksched_yield(struct ksched *ksched)
219 {
220 sched_relinquish(curthread);
221 return 0;
222 }
223
224 int
225 ksched_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
247 int
248 ksched_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
270 int
271 ksched_rr_get_interval(struct ksched *ksched,
272 struct thread *td, struct timespec *timespec)
273 {
274 *timespec = ksched->rr_interval;
275
276 return 0;
277 }
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