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Diff for /funnyos/kern/kern_sched.c between version 1.1 and 1.3

version 1.1, 2007/11/19 15:54:33 version 1.3, 2007/11/23 13:37:43
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  */   */
 #include <sys/types.h>  #include <sys/types.h>
 #include <sys/kern_sched.h>  #include <sys/kern_sched.h>
   #include <sys/kern_time.h> /* for HZ */
   #include <sys/mem.h>
   
 #include <libkern/printf.h>  #include <libkern/printf.h>
   
   /* #define SCHED_DEBUG */
   /* #define SCHED_REGDEBUG */
   
   #ifdef SCHED_DEBUG
   #define DPRINTF(x...)   do { printf(x); } while (0)
   #else
   #define DPRINTF(x...)   { }
   #endif
   
   #ifdef SCHED_REGDEBUG
   #define DRPRINTF(x...)  do { printf(x); } while (0)
   #else
   #define DRPRINTF(x...)  { }
   #endif
   
   
   /* config.c gives us tasks that we'll schedule */
   extern struct u_task config_tasklist[];
   
   /* list of k_tasks */
   struct k_task *ktasklist;
   
   /* current running task */
   struct k_task *curktask;
   
   /* pcb of running task; we will save context there when enter irq_mode */
   struct pcb *curpcb;
   
   /* interrupt frame */
   extern struct pcb *iframep;
   
   /* total tasks; used to TID generation */
   uint8_t ntasks;
   
   /* "idle" task exists forever and occupy cpu when there is no other task pretending. */
   const struct u_task idle_utask = {"idle", 0, NULL};
   
   
   void
   sched_init(void)
   {
           /*
            * Create struct k_task for each u_task that user described in config_tasklist.
            */
           struct u_task *utaskp;
           struct k_task *ktaskp, *oldktaskp;
   
           ntasks = 0;
   
           /*
            * Create an "idle" task which always has TID 0.
            */
           ktaskp = kmalloc(sizeof(struct k_task));
   
           if (ktaskp == NULL)
                   panic("can't allocate memory for idle task\n");
   
           /* link u_task for idle task */
           ktaskp->kt_utask = (struct u_task *)&idle_utask;
   
           /* TID (always 0) */
           ktaskp->kt_tid = 0;
   
           /* idle task is always in state READY (or RUNNING, if on processor now) */
           ktaskp->kt_state = TASK_READY;
   
           /* next task in list isn't up yet (and prev too) */
           ktaskp->kt_next = NULL;
   
           /* make "idle" task first task in ktasklist, system k_task list */
           ktasklist = ktaskp;
   
           /* bump ntasks to 1 */
           ntasks = 1;
   
           /* preserve pointer to this k_task so we can link-in next task */
           oldktaskp = ktaskp;
   
           /*
            * Idle task set up completed.
            * Configure all other system tasks,
            */
   
           /* look through tasklist */
           utaskp = config_tasklist;
           while(utaskp->ut_name != NULL) {
   
                   /* try to allocate memory for ktask */
                   ktaskp = kmalloc(sizeof(struct k_task));
   
                   if (ktaskp == NULL)
                           panic("can't allocate memory for task '%s'\n", utaskp->ut_name);
   
                   /*
                    * Successfully allocated new ktask.
                    */
   
                   /* link u_task */
                   ktaskp->kt_utask = utaskp;
   
                   /* set TID (Task Identificator) */
                   ktaskp->kt_tid = oldktaskp->kt_tid + 1;
   
                   /* state */
                   ktaskp->kt_state = TASK_READY;
   
                   /* set intitial entry point (initial pc) to task_enter */
                   ktaskp->kt_pcb.p_pc = (uint32_t)ktaskp->kt_utask->ut_enter;
   
                   /* link current task in previous task's structure */
                   oldktaskp->kt_next = ktaskp;
   
                   /* NULLify kt_next of current task */
                   ktaskp->kt_next = NULL;
   
                   /* save current ktask for use with next ktask */
                   oldktaskp = ktaskp;
   
                   /* bump ntasks */
                   ntasks++;
   
                   /* shift to next element in config_tasklist[] */
                   utaskp++;
           }
   
           /* make this list circularly linked (e.g point list's last->next node into first) */
           ktaskp->kt_next = ktasklist;
   
           DPRINTF("kern_sched: created %d tasks:", ntasks);
   
           /* print tasks' names */
           ktaskp = ktasklist + 1; /* skip (first) "idle" task (display it as the end of circularly list) */
           do {
                   DPRINTF(" %s", ktaskp->kt_utask->ut_name);
   
                   if (ktaskp->kt_tid == NULL) /* that was an "idle" task */
                           break;
   
                   ktaskp = ktaskp->kt_next;
           } while(1);
   
           DPRINTF("; HZ=%d\n", HZ);
   
           /*
            * Run "idle" task in NOSCHED, so it will not schedule after first context siwtch;
            */
           ktasklist->kt_state = TASK_NOSCHED;
           curktask = ktasklist; /* ktasklist always points to "idle" task */
   
           /* point curpcb */
           curpcb = &ktasklist->kt_pcb;
   }
   
   
   void
   sched_tick(void)
   {
           /*
            * Schedule next task that will occupy cpu (if any).
            * Remember that we are in IRQ_mode here.
            */
   
           /*
            * All we need to do now is:
            *  - see if context switch is required
            *   - if so, save iframe into curpcb (save hardware context)
            *   - select next task to run
            *   - point curpcb to pcb of new task
            *   - point curktask to k_task of new task
            *   - copy curpcb into iframep (so we'll continue in another task when we exit irq_mode)
            *  - if context switch is not required
            *   - XXX we will not copy curpcb into iframep? (cause we end up in same task at next irq)
            *  - anyway, account time, etc..
            */
   
           /* XXX use pre-emtive multitasking to simplify things for now! */
   
           /* save hardware state of interrupted task */
           *curpcb = *iframep;
   
           /* "suspend" interrupted task */
           if(curktask->kt_state == TASK_RUNNING) /* XXX ugly hack to skip "idle" which is NOSCHED */
                   curktask->kt_state = TASK_READY;
   
           DPRINTF("sched_tick: task tid=%d (\"%s\") suspended\n", curktask->kt_tid, curktask->kt_utask->ut_name);
           DRPRINTF("r0=0x%x\n", iframep->p_r0);
           DRPRINTF("r1=0x%x\n", iframep->p_r1);
           DRPRINTF("r2=0x%x\n", iframep->p_r2);
           DRPRINTF("r3=0x%x\n", iframep->p_r3);
           DRPRINTF("r4=0x%x\n", iframep->p_r4);
           DRPRINTF("r5=0x%x\n", iframep->p_r5);
           DRPRINTF("r6=0x%x\n", iframep->p_r6);
           DRPRINTF("r7=0x%x\n", iframep->p_r7);
           DRPRINTF("r8=0x%x\n", iframep->p_r8);
           DRPRINTF("r9=0x%x\n", iframep->p_r9);
           DRPRINTF("r10=0x%x\n", iframep->p_r10);
           DRPRINTF("r11=0x%x\n", iframep->p_r11);
           DRPRINTF("r12=0x%x\n", iframep->p_r12);
           DRPRINTF("pc=0x%x\n", iframep->p_pc);
   
           /* round-robin select next task in circlelist */
           curktask = curktask->kt_next;
   
           /* look for next ready task */
           while(curktask->kt_state != TASK_READY)
                   curktask = curktask->kt_next;
   
           /* run selected task */
           curktask->kt_state = TASK_RUNNING;
   
           /* point curpcb into selected task's pcb */
           curpcb = &curktask->kt_pcb;
   
           /* restore selected task's hardware context into an IRQ stack */
           *iframep = *curpcb;
   
           DPRINTF("sched_tick: task tid=%d (\"%s\") resumed\n", curktask->kt_tid, curktask->kt_utask->ut_name);
           DRPRINTF("r0=0x%x\n", iframep->p_r0);
           DRPRINTF("r1=0x%x\n", iframep->p_r1);
           DRPRINTF("r2=0x%x\n", iframep->p_r2);
           DRPRINTF("r3=0x%x\n", iframep->p_r3);
           DRPRINTF("r4=0x%x\n", iframep->p_r4);
           DRPRINTF("r5=0x%x\n", iframep->p_r5);
           DRPRINTF("r6=0x%x\n", iframep->p_r6);
           DRPRINTF("r7=0x%x\n", iframep->p_r7);
           DRPRINTF("r8=0x%x\n", iframep->p_r8);
           DRPRINTF("r9=0x%x\n", iframep->p_r9);
           DRPRINTF("r10=0x%x\n", iframep->p_r10);
           DRPRINTF("r11=0x%x\n", iframep->p_r11);
           DRPRINTF("r12=0x%x\n", iframep->p_r12);
           DRPRINTF("pc=0x%x\n", iframep->p_pc);
   
   }
   
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