direct-io.hg

view extras/mini-os/sched.c @ 15481:538c3d8aa4b1

Revert 15471:7ac7f147241405af83e7a9d748cf7b01279734fc

Block-device specifiers in ioemu can contain colons, so skipping
always past the first colon is not a good idea. Better solutions are
in the pipeline to solve the blktap issues.

Signed-off-by: Keir Fraser <keir@xensource.com>
author kfraser@localhost.localdomain
date Fri Jul 06 15:01:20 2007 +0100 (2007-07-06)
parents e9e327c3e81b
children
line source
1 /*
2 ****************************************************************************
3 * (C) 2005 - Grzegorz Milos - Intel Research Cambridge
4 ****************************************************************************
5 *
6 * File: sched.c
7 * Author: Grzegorz Milos
8 * Changes: Robert Kaiser
9 *
10 * Date: Aug 2005
11 *
12 * Environment: Xen Minimal OS
13 * Description: simple scheduler for Mini-Os
14 *
15 * The scheduler is non-preemptive (cooperative), and schedules according
16 * to Round Robin algorithm.
17 *
18 ****************************************************************************
19 * Permission is hereby granted, free of charge, to any person obtaining a copy
20 * of this software and associated documentation files (the "Software"), to
21 * deal in the Software without restriction, including without limitation the
22 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
23 * sell copies of the Software, and to permit persons to whom the Software is
24 * furnished to do so, subject to the following conditions:
25 *
26 * The above copyright notice and this permission notice shall be included in
27 * all copies or substantial portions of the Software.
28 *
29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
30 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
32 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
33 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
34 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
35 * DEALINGS IN THE SOFTWARE.
36 */
38 #include <os.h>
39 #include <hypervisor.h>
40 #include <time.h>
41 #include <mm.h>
42 #include <types.h>
43 #include <lib.h>
44 #include <xmalloc.h>
45 #include <list.h>
46 #include <sched.h>
47 #include <semaphore.h>
50 #ifdef SCHED_DEBUG
51 #define DEBUG(_f, _a...) \
52 printk("MINI_OS(file=sched.c, line=%d) " _f "\n", __LINE__, ## _a)
53 #else
54 #define DEBUG(_f, _a...) ((void)0)
55 #endif
57 struct thread *idle_thread = NULL;
58 LIST_HEAD(exited_threads);
60 void inline print_runqueue(void)
61 {
62 struct list_head *it;
63 struct thread *th;
64 list_for_each(it, &idle_thread->thread_list)
65 {
66 th = list_entry(it, struct thread, thread_list);
67 printk(" Thread \"%s\", runnable=%d\n", th->name, is_runnable(th));
68 }
69 printk("\n");
70 }
72 /* Find the time when the next timeout expires. If this is more than
73 10 seconds from now, return 10 seconds from now. */
74 static s_time_t blocking_time(void)
75 {
76 struct thread *thread;
77 struct list_head *iterator;
78 s_time_t min_wakeup_time;
79 unsigned long flags;
80 local_irq_save(flags);
81 /* default-block the domain for 10 seconds: */
82 min_wakeup_time = NOW() + SECONDS(10);
84 /* Thread list needs to be protected */
85 list_for_each(iterator, &idle_thread->thread_list)
86 {
87 thread = list_entry(iterator, struct thread, thread_list);
88 if(!is_runnable(thread) && thread->wakeup_time != 0LL)
89 {
90 if(thread->wakeup_time < min_wakeup_time)
91 {
92 min_wakeup_time = thread->wakeup_time;
93 }
94 }
95 }
96 local_irq_restore(flags);
97 return(min_wakeup_time);
98 }
100 /* Wake up all threads with expired timeouts. */
101 static void wake_expired(void)
102 {
103 struct thread *thread;
104 struct list_head *iterator;
105 s_time_t now = NOW();
106 unsigned long flags;
107 local_irq_save(flags);
108 /* Thread list needs to be protected */
109 list_for_each(iterator, &idle_thread->thread_list)
110 {
111 thread = list_entry(iterator, struct thread, thread_list);
112 if(!is_runnable(thread) && thread->wakeup_time != 0LL)
113 {
114 if(thread->wakeup_time <= now)
115 wake(thread);
116 }
117 }
118 local_irq_restore(flags);
119 }
121 void schedule(void)
122 {
123 struct thread *prev, *next, *thread;
124 struct list_head *iterator;
125 unsigned long flags;
126 prev = current;
127 local_irq_save(flags);
128 list_for_each(iterator, &exited_threads)
129 {
130 thread = list_entry(iterator, struct thread, thread_list);
131 if(thread != prev)
132 {
133 list_del(&thread->thread_list);
134 free_pages(thread->stack, 1);
135 xfree(thread);
136 }
137 }
138 next = idle_thread;
139 /* Thread list needs to be protected */
140 list_for_each(iterator, &idle_thread->thread_list)
141 {
142 thread = list_entry(iterator, struct thread, thread_list);
143 if(is_runnable(thread))
144 {
145 next = thread;
146 /* Put this thread on the end of the list */
147 list_del(&thread->thread_list);
148 list_add_tail(&thread->thread_list, &idle_thread->thread_list);
149 break;
150 }
151 }
152 local_irq_restore(flags);
153 /* Interrupting the switch is equivalent to having the next thread
154 inturrupted at the return instruction. And therefore at safe point. */
155 if(prev != next) switch_threads(prev, next);
156 }
158 struct thread* create_thread(char *name, void (*function)(void *), void *data)
159 {
160 struct thread *thread;
161 unsigned long flags;
162 /* Call architecture specific setup. */
163 thread = arch_create_thread(name, function, data);
164 /* Not runable, not exited, not sleeping */
165 thread->flags = 0;
166 thread->wakeup_time = 0LL;
167 set_runnable(thread);
168 local_irq_save(flags);
169 if(idle_thread != NULL) {
170 list_add_tail(&thread->thread_list, &idle_thread->thread_list);
171 } else if(function != idle_thread_fn)
172 {
173 printk("BUG: Not allowed to create thread before initialising scheduler.\n");
174 BUG();
175 }
176 local_irq_restore(flags);
177 return thread;
178 }
180 void exit_thread(void)
181 {
182 unsigned long flags;
183 struct thread *thread = current;
184 printk("Thread \"%s\" exited.\n", thread->name);
185 local_irq_save(flags);
186 /* Remove from the thread list */
187 list_del(&thread->thread_list);
188 clear_runnable(thread);
189 /* Put onto exited list */
190 list_add(&thread->thread_list, &exited_threads);
191 local_irq_restore(flags);
192 /* Schedule will free the resources */
193 schedule();
194 }
196 void block(struct thread *thread)
197 {
198 thread->wakeup_time = 0LL;
199 clear_runnable(thread);
200 }
202 void sleep(u32 millisecs)
203 {
204 struct thread *thread = get_current();
205 thread->wakeup_time = NOW() + MILLISECS(millisecs);
206 clear_runnable(thread);
207 schedule();
208 }
210 void wake(struct thread *thread)
211 {
212 thread->wakeup_time = 0LL;
213 set_runnable(thread);
214 }
216 void idle_thread_fn(void *unused)
217 {
218 s_time_t until;
219 for(;;)
220 {
221 schedule();
222 /* block until the next timeout expires, or for 10 secs, whichever comes first */
223 until = blocking_time();
224 block_domain(until);
225 wake_expired();
226 }
227 }
229 DECLARE_MUTEX(mutex);
231 void th_f1(void *data)
232 {
233 struct timeval tv1, tv2;
235 for(;;)
236 {
237 down(&mutex);
238 printk("Thread \"%s\" got semaphore, runnable %d\n", current->name, is_runnable(current));
239 schedule();
240 printk("Thread \"%s\" releases the semaphore\n", current->name);
241 up(&mutex);
244 gettimeofday(&tv1);
245 for(;;)
246 {
247 gettimeofday(&tv2);
248 if(tv2.tv_sec - tv1.tv_sec > 2) break;
249 }
252 schedule();
253 }
254 }
256 void th_f2(void *data)
257 {
258 for(;;)
259 {
260 printk("Thread OTHER executing, data 0x%lx\n", data);
261 schedule();
262 }
263 }
267 void init_sched(void)
268 {
269 printk("Initialising scheduler\n");
271 idle_thread = create_thread("Idle", idle_thread_fn, NULL);
272 INIT_LIST_HEAD(&idle_thread->thread_list);
273 }