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/10.1/sys/kern/ksched.c 239183 2012-08-10 18:19:57Z mav $");
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/sysctl.h>
45 #include <sys/kernel.h>
46 #include <sys/mutex.h>
47 #include <sys/proc.h>
48 #include <sys/posix4.h>
49 #include <sys/resource.h>
50 #include <sys/sched.h>
51
52 FEATURE(kposix_priority_scheduling, "POSIX P1003.1B realtime extensions");
53
54 /* ksched: Real-time extension to support POSIX priority scheduling.
55 */
56
57 struct ksched {
58 struct timespec rr_interval;
59 };
60
61 int
62 ksched_attach(struct ksched **p)
63 {
64 struct ksched *ksched= p31b_malloc(sizeof(*ksched));
65
66 ksched->rr_interval.tv_sec = 0;
67 ksched->rr_interval.tv_nsec = 1000000000L / hz * sched_rr_interval();
68
69 *p = ksched;
70 return 0;
71 }
72
73 int
74 ksched_detach(struct ksched *ks)
75 {
76 p31b_free(ks);
77
78 return 0;
79 }
80
81 /*
82 * XXX About priorities
83 *
84 * POSIX 1003.1b requires that numerically higher priorities be of
85 * higher priority. It also permits sched_setparam to be
86 * implementation defined for SCHED_OTHER. I don't like
87 * the notion of inverted priorites for normal processes when
88 * you can use "setpriority" for that.
89 *
90 */
91
92 /* Macros to convert between the unix (lower numerically is higher priority)
93 * and POSIX 1003.1b (higher numerically is higher priority)
94 */
95
96 #define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
97 #define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
98
99 #define p4prio_to_tsprio(P) ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) - (P))
100 #define tsprio_to_p4prio(P) ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) - (P))
101
102 /* These improve readability a bit for me:
103 */
104 #define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
105 #define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
106
107 static __inline int
108 getscheduler(struct ksched *ksched, struct thread *td, int *policy)
109 {
110 struct rtprio rtp;
111 int e = 0;
112
113 pri_to_rtp(td, &rtp);
114 switch (rtp.type)
115 {
116 case RTP_PRIO_FIFO:
117 *policy = SCHED_FIFO;
118 break;
119
120 case RTP_PRIO_REALTIME:
121 *policy = SCHED_RR;
122 break;
123
124 default:
125 *policy = SCHED_OTHER;
126 break;
127 }
128
129 return e;
130 }
131
132 int
133 ksched_setparam(struct ksched *ksched,
134 struct thread *td, const struct sched_param *param)
135 {
136 int policy;
137 int e;
138
139 e = getscheduler(ksched, td, &policy);
140
141 if (e == 0)
142 {
143 e = ksched_setscheduler(ksched, td, policy, param);
144 }
145
146 return e;
147 }
148
149 int
150 ksched_getparam(struct ksched *ksched,
151 struct thread *td, struct sched_param *param)
152 {
153 struct rtprio rtp;
154
155 pri_to_rtp(td, &rtp);
156 if (RTP_PRIO_IS_REALTIME(rtp.type))
157 param->sched_priority = rtpprio_to_p4prio(rtp.prio);
158 else {
159 if (PRI_MIN_TIMESHARE < rtp.prio)
160 /*
161 * The interactive score has it to min realtime
162 * so we must show max (64 most likely
163 */
164 param->sched_priority = (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE);
165 else
166 param->sched_priority = tsprio_to_p4prio(rtp.prio);
167 }
168 return 0;
169 }
170
171 /*
172 * XXX The priority and scheduler modifications should
173 * be moved into published interfaces in kern/kern_sync.
174 *
175 * The permissions to modify process p were checked in "p31b_proc()".
176 *
177 */
178 int
179 ksched_setscheduler(struct ksched *ksched,
180 struct thread *td, int policy, const struct sched_param *param)
181 {
182 int e = 0;
183 struct rtprio rtp;
184
185 switch(policy)
186 {
187 case SCHED_RR:
188 case SCHED_FIFO:
189
190 if (param->sched_priority >= P1B_PRIO_MIN &&
191 param->sched_priority <= P1B_PRIO_MAX)
192 {
193 rtp.prio = p4prio_to_rtpprio(param->sched_priority);
194 rtp.type = (policy == SCHED_FIFO)
195 ? RTP_PRIO_FIFO : RTP_PRIO_REALTIME;
196
197 rtp_to_pri(&rtp, td);
198 }
199 else
200 e = EPERM;
201
202
203 break;
204
205 case SCHED_OTHER:
206 if (param->sched_priority >= 0 &&
207 param->sched_priority <= (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE)) {
208 rtp.type = RTP_PRIO_NORMAL;
209 rtp.prio = p4prio_to_tsprio(param->sched_priority);
210 rtp_to_pri(&rtp, td);
211 } else
212 e = EINVAL;
213
214 break;
215
216 default:
217 e = EINVAL;
218 break;
219 }
220
221 return e;
222 }
223
224 int
225 ksched_getscheduler(struct ksched *ksched, struct thread *td, int *policy)
226 {
227 return getscheduler(ksched, td, policy);
228 }
229
230 /* ksched_yield: Yield the CPU.
231 */
232 int
233 ksched_yield(struct ksched *ksched)
234 {
235 sched_relinquish(curthread);
236 return 0;
237 }
238
239 int
240 ksched_get_priority_max(struct ksched *ksched, int policy, int *prio)
241 {
242 int e = 0;
243
244 switch (policy)
245 {
246 case SCHED_FIFO:
247 case SCHED_RR:
248 *prio = RTP_PRIO_MAX;
249 break;
250
251 case SCHED_OTHER:
252 *prio = PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE;
253 break;
254
255 default:
256 e = EINVAL;
257 }
258
259 return e;
260 }
261
262 int
263 ksched_get_priority_min(struct ksched *ksched, int policy, int *prio)
264 {
265 int e = 0;
266
267 switch (policy)
268 {
269 case SCHED_FIFO:
270 case SCHED_RR:
271 *prio = P1B_PRIO_MIN;
272 break;
273
274 case SCHED_OTHER:
275 *prio = 0;
276 break;
277
278 default:
279 e = EINVAL;
280 }
281
282 return e;
283 }
284
285 int
286 ksched_rr_get_interval(struct ksched *ksched,
287 struct thread *td, struct timespec *timespec)
288 {
289 *timespec = ksched->rr_interval;
290
291 return 0;
292 }
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