kern

annotate src/sched.c @ 59:ef9cc2e90277

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added a comment describing the push of just_forked address to the stack frame of the newly-forked process.
author John Tsiombikas <nuclear@member.fsf.org>
date Wed, 17 Aug 2011 05:33:03 +0300
parents 0be4615594df
children 3941e82b07f2
rev   line source
nuclear@51 1 #include <stdio.h>
nuclear@55 2 #include <assert.h>
nuclear@51 3 #include "sched.h"
nuclear@51 4 #include "proc.h"
nuclear@51 5 #include "intr.h"
nuclear@51 6 #include "asmops.h"
nuclear@51 7 #include "config.h"
nuclear@51 8
nuclear@55 9 #define EMPTY(q) ((q)->head == 0)
nuclear@51 10
nuclear@51 11 struct proc_list {
nuclear@51 12 struct process *head, *tail;
nuclear@51 13 };
nuclear@51 14
nuclear@55 15 static void idle_proc(void);
nuclear@55 16 static void ins_back(struct proc_list *list, struct process *proc);
nuclear@55 17 static void ins_front(struct proc_list *list, struct process *proc);
nuclear@55 18 static void remove(struct proc_list *list, struct process *proc);
nuclear@55 19 static int hash_addr(void *addr);
nuclear@51 20
nuclear@51 21 static struct proc_list runq;
nuclear@51 22 static struct proc_list zombieq;
nuclear@51 23
nuclear@55 24 #define HTBL_SIZE 101
nuclear@55 25 static struct proc_list wait_htable[HTBL_SIZE];
nuclear@55 26
nuclear@55 27
nuclear@51 28 void schedule(void)
nuclear@51 29 {
nuclear@52 30 disable_intr();
nuclear@52 31
nuclear@55 32 if(EMPTY(&runq)) {
nuclear@56 33 if(!get_current_proc()) {
nuclear@56 34 /* we're already in the idle process, don't reenter it
nuclear@56 35 * or you'll fill up the stack very quickly.
nuclear@56 36 */
nuclear@56 37 return;
nuclear@56 38 }
nuclear@56 39
nuclear@55 40 idle_proc();
nuclear@56 41 return;
nuclear@51 42 }
nuclear@51 43
nuclear@51 44 /* if the current process exhausted its timeslice,
nuclear@51 45 * move it to the back of the queue.
nuclear@51 46 */
nuclear@51 47 if(runq.head->ticks_left <= 0) {
nuclear@51 48 if(runq.head->next) {
nuclear@51 49 struct process *proc = runq.head;
nuclear@51 50 remove(&runq, proc);
nuclear@51 51 ins_back(&runq, proc);
nuclear@51 52 }
nuclear@51 53
nuclear@51 54 /* start a new timeslice */
nuclear@51 55 runq.head->ticks_left = TIMESLICE_TICKS;
nuclear@51 56 }
nuclear@51 57
nuclear@55 58 /* always enter context_switch with interrupts disabled */
nuclear@51 59 context_switch(runq.head->id);
nuclear@51 60 }
nuclear@51 61
nuclear@55 62 void add_proc(int pid)
nuclear@51 63 {
nuclear@51 64 int istate;
nuclear@52 65 struct process *proc;
nuclear@51 66
nuclear@51 67 istate = get_intr_state();
nuclear@51 68 disable_intr();
nuclear@51 69
nuclear@52 70 proc = get_process(pid);
nuclear@52 71
nuclear@51 72 ins_back(&runq, proc);
nuclear@53 73 proc->state = STATE_RUNNABLE;
nuclear@51 74
nuclear@51 75 set_intr_state(istate);
nuclear@51 76 }
nuclear@51 77
nuclear@55 78 /* block the process until we get a wakeup call for address ev */
nuclear@55 79 void wait(void *wait_addr)
nuclear@55 80 {
nuclear@55 81 struct process *p;
nuclear@55 82 int hash_idx;
nuclear@51 83
nuclear@55 84 disable_intr();
nuclear@55 85
nuclear@55 86 p = get_current_proc();
nuclear@55 87 assert(p);
nuclear@55 88
nuclear@55 89 /* remove it from the runqueue ... */
nuclear@55 90 remove(&runq, p);
nuclear@55 91
nuclear@55 92 /* and place it in the wait hash table based on sleep_addr */
nuclear@55 93 hash_idx = hash_addr(wait_addr);
nuclear@55 94 ins_back(wait_htable + hash_idx, p);
nuclear@55 95
nuclear@55 96 p->state = STATE_BLOCKED;
nuclear@55 97 p->wait_addr = wait_addr;
nuclear@56 98
nuclear@56 99 /* call the scheduler to give time to another process */
nuclear@56 100 schedule();
nuclear@55 101 }
nuclear@55 102
nuclear@55 103 /* wake up all the processes sleeping on this address */
nuclear@55 104 void wakeup(void *wait_addr)
nuclear@51 105 {
nuclear@55 106 int hash_idx;
nuclear@55 107 struct process *iter;
nuclear@55 108 struct proc_list *list;
nuclear@55 109
nuclear@55 110 hash_idx = hash_addr(wait_addr);
nuclear@55 111 list = wait_htable + hash_idx;
nuclear@55 112
nuclear@55 113 iter = list->head;
nuclear@55 114 while(iter) {
nuclear@55 115 if(iter->wait_addr == wait_addr) {
nuclear@55 116 /* found one, remove it, and make it runnable */
nuclear@55 117 struct process *p = iter;
nuclear@55 118 iter = iter->next;
nuclear@55 119
nuclear@55 120 remove(list, p);
nuclear@55 121 p->state = STATE_RUNNABLE;
nuclear@55 122 ins_back(&runq, p);
nuclear@55 123 } else {
nuclear@55 124 iter = iter->next;
nuclear@55 125 }
nuclear@55 126 }
nuclear@55 127 }
nuclear@55 128
nuclear@55 129 static void idle_proc(void)
nuclear@55 130 {
nuclear@55 131 /* make sure we send any pending EOIs if needed.
nuclear@55 132 * end_of_irq will actually check if it's needed first.
nuclear@55 133 */
nuclear@55 134 struct intr_frame *ifrm = get_intr_frame();
nuclear@55 135 end_of_irq(INTR_TO_IRQ(ifrm->inum));
nuclear@55 136
nuclear@56 137 set_current_pid(0);
nuclear@56 138
nuclear@57 139 printf("idle loop is running\n");
nuclear@57 140
nuclear@55 141 /* make sure interrupts are enabled before halting */
nuclear@56 142 while(EMPTY(&runq)) {
nuclear@56 143 enable_intr();
nuclear@56 144 halt_cpu();
nuclear@56 145 disable_intr();
nuclear@56 146 }
nuclear@55 147 }
nuclear@55 148
nuclear@55 149
nuclear@55 150 /* list operations */
nuclear@55 151 static void ins_back(struct proc_list *list, struct process *proc)
nuclear@55 152 {
nuclear@55 153 if(EMPTY(list)) {
nuclear@55 154 list->head = proc;
nuclear@51 155 } else {
nuclear@55 156 list->tail->next = proc;
nuclear@51 157 }
nuclear@51 158
nuclear@51 159 proc->next = 0;
nuclear@55 160 proc->prev = list->tail;
nuclear@55 161 list->tail = proc;
nuclear@51 162 }
nuclear@51 163
nuclear@55 164 static void ins_front(struct proc_list *list, struct process *proc)
nuclear@51 165 {
nuclear@55 166 if(EMPTY(list)) {
nuclear@55 167 list->tail = proc;
nuclear@51 168 } else {
nuclear@55 169 list->head->prev = proc;
nuclear@51 170 }
nuclear@51 171
nuclear@55 172 proc->next = list->head;
nuclear@51 173 proc->prev = 0;
nuclear@55 174 list->head = proc;
nuclear@51 175 }
nuclear@51 176
nuclear@55 177 static void remove(struct proc_list *list, struct process *proc)
nuclear@51 178 {
nuclear@51 179 if(proc->prev) {
nuclear@51 180 proc->prev->next = proc->next;
nuclear@51 181 }
nuclear@51 182 if(proc->next) {
nuclear@51 183 proc->next->prev = proc->prev;
nuclear@51 184 }
nuclear@55 185 if(list->head == proc) {
nuclear@55 186 list->head = proc->next;
nuclear@51 187 }
nuclear@55 188 if(list->tail == proc) {
nuclear@55 189 list->tail = proc->prev;
nuclear@51 190 }
nuclear@51 191 }
nuclear@55 192
nuclear@55 193 static int hash_addr(void *addr)
nuclear@55 194 {
nuclear@55 195 return (uint32_t)addr % HTBL_SIZE;
nuclear@55 196 }