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/8.3/sys/kern/ksched.c 223037 2011-06-13 06:32:56Z davidxu $");
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 */
87
88 /* Macros to convert between the unix (lower numerically is higher priority)
89 * and POSIX 1003.1b (higher numerically is higher priority)
90 */
91
92 #define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
93 #define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
94
95 #define p4prio_to_tsprio(P) ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) - (P))
96 #define tsprio_to_p4prio(P) ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) - (P))
97
98 /* These improve readability a bit for me:
99 */
100 #define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
101 #define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
102
103 static __inline int
104 getscheduler(struct ksched *ksched, struct thread *td, int *policy)
105 {
106 struct rtprio rtp;
107 int e = 0;
108
109 pri_to_rtp(td, &rtp);
110 switch (rtp.type)
111 {
112 case RTP_PRIO_FIFO:
113 *policy = SCHED_FIFO;
114 break;
115
116 case RTP_PRIO_REALTIME:
117 *policy = SCHED_RR;
118 break;
119
120 default:
121 *policy = SCHED_OTHER;
122 break;
123 }
124
125 return e;
126 }
127
128 int
129 ksched_setparam(struct ksched *ksched,
130 struct thread *td, const struct sched_param *param)
131 {
132 int policy;
133 int e;
134
135 e = getscheduler(ksched, td, &policy);
136
137 if (e == 0)
138 {
139 e = ksched_setscheduler(ksched, td, policy, param);
140 }
141
142 return e;
143 }
144
145 int
146 ksched_getparam(struct ksched *ksched,
147 struct thread *td, struct sched_param *param)
148 {
149 struct rtprio rtp;
150
151 pri_to_rtp(td, &rtp);
152 if (RTP_PRIO_IS_REALTIME(rtp.type))
153 param->sched_priority = rtpprio_to_p4prio(rtp.prio);
154 else {
155 if (PRI_MIN_TIMESHARE < rtp.prio)
156 /*
157 * The interactive score has it to min realtime
158 * so we must show max (64 most likely
159 */
160 param->sched_priority = (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE);
161 else
162 param->sched_priority = tsprio_to_p4prio(rtp.prio);
163 }
164 return 0;
165 }
166
167 /*
168 * XXX The priority and scheduler modifications should
169 * be moved into published interfaces in kern/kern_sync.
170 *
171 * The permissions to modify process p were checked in "p31b_proc()".
172 *
173 */
174 int
175 ksched_setscheduler(struct ksched *ksched,
176 struct thread *td, int policy, const struct sched_param *param)
177 {
178 int e = 0;
179 struct rtprio rtp;
180
181 switch(policy)
182 {
183 case SCHED_RR:
184 case SCHED_FIFO:
185
186 if (param->sched_priority >= P1B_PRIO_MIN &&
187 param->sched_priority <= P1B_PRIO_MAX)
188 {
189 rtp.prio = p4prio_to_rtpprio(param->sched_priority);
190 rtp.type = (policy == SCHED_FIFO)
191 ? RTP_PRIO_FIFO : RTP_PRIO_REALTIME;
192
193 rtp_to_pri(&rtp, td);
194 }
195 else
196 e = EPERM;
197
198
199 break;
200
201 case SCHED_OTHER:
202 if (param->sched_priority >= 0 &&
203 param->sched_priority <= (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE)) {
204 rtp.type = RTP_PRIO_NORMAL;
205 rtp.prio = p4prio_to_tsprio(param->sched_priority);
206 rtp_to_pri(&rtp, td);
207 } else
208 e = EINVAL;
209
210 break;
211
212 default:
213 e = EINVAL;
214 break;
215 }
216
217 return e;
218 }
219
220 int
221 ksched_getscheduler(struct ksched *ksched, struct thread *td, int *policy)
222 {
223 return getscheduler(ksched, td, policy);
224 }
225
226 /* ksched_yield: Yield the CPU.
227 */
228 int
229 ksched_yield(struct ksched *ksched)
230 {
231 sched_relinquish(curthread);
232 return 0;
233 }
234
235 int
236 ksched_get_priority_max(struct ksched *ksched, int policy, int *prio)
237 {
238 int e = 0;
239
240 switch (policy)
241 {
242 case SCHED_FIFO:
243 case SCHED_RR:
244 *prio = RTP_PRIO_MAX;
245 break;
246
247 case SCHED_OTHER:
248 *prio = PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE;
249 break;
250
251 default:
252 e = EINVAL;
253 }
254
255 return e;
256 }
257
258 int
259 ksched_get_priority_min(struct ksched *ksched, int policy, int *prio)
260 {
261 int e = 0;
262
263 switch (policy)
264 {
265 case SCHED_FIFO:
266 case SCHED_RR:
267 *prio = P1B_PRIO_MIN;
268 break;
269
270 case SCHED_OTHER:
271 *prio = 0;
272 break;
273
274 default:
275 e = EINVAL;
276 }
277
278 return e;
279 }
280
281 int
282 ksched_rr_get_interval(struct ksched *ksched,
283 struct thread *td, struct timespec *timespec)
284 {
285 *timespec = ksched->rr_interval;
286
287 return 0;
288 }
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