minix/servers/sched/main.c

   1 /* This file contains the main program of the SCHED scheduler. It will sit idle
   2  * until asked, by PM, to take over scheduling a particular process.
   3  */
   4
   5 /* The _MAIN def indicates that we want the schedproc structs to be created
   6  * here. Used from within schedproc.h */
   7 #define _MAIN
   8
   9 #include "sched.h"
  10 #include "schedproc.h"
  11
  12 /* Declare some local functions. */
  13 static void reply(endpoint_t whom, message *m_ptr);
  14 static void sef_local_startup(void);
  15 static int sef_cb_init_fresh(int type, sef_init_info_t *info);
  16
  17 struct machine machine;         /* machine info */
  18
  19 /*===========================================================================*
  20  *                              main                                         *
  21  *===========================================================================*/
  22 int main(void)
  23 {
  24         /* Main routine of the scheduler. */
  25         message m_in;   /* the incoming message itself is kept here. */
  26         int call_nr;    /* system call number */
  27         int who_e;      /* caller's endpoint */
  28         int result;     /* result to system call */
  29         int rv;
  30
  31         /* SEF local startup. */
  32         sef_local_startup();
  33
  34         /* This is SCHED's main loop - get work and do it, forever and forever. */
  35         while (TRUE) {
  36                 int ipc_status;
  37
  38                 /* Wait for the next message and extract useful information from it. */
  39                 if (sef_receive_status(ANY, &m_in, &ipc_status) != OK)
  40                         panic("SCHED sef_receive error");
  41                 who_e = m_in.m_source;  /* who sent the message */
  42                 call_nr = m_in.m_type;  /* system call number */
  43
  44                 /* Check for system notifications first. Special cases. */
  45                 if (is_ipc_notify(ipc_status)) {
  46                         switch(who_e) {
  47                         case CLOCK:
  48                                 balance_queues();
  49                                 break;
  50                         default :
  51                                 break;
  52                         }
  53
  54                         continue; /* Don't reply. */
  55                 }
  56
  57                 switch(call_nr) {
  58                 case SCHEDULING_INHERIT:
  59                 case SCHEDULING_START:
  60                         result = do_start_scheduling(&m_in);
  61                         break;
  62                 case SCHEDULING_STOP:
  63                         result = do_stop_scheduling(&m_in);
  64                         break;
  65                 case SCHEDULING_SET_NICE:
  66                         result = do_nice(&m_in);
  67                         break;
  68                 case SCHEDULING_NO_QUANTUM:
  69                         /* This message was sent from the kernel, don't reply */
  70                         if (IPC_STATUS_FLAGS_TEST(ipc_status,
  71                                 IPC_FLG_MSG_FROM_KERNEL)) {
  72                                 if ((rv = do_noquantum(&m_in)) != (OK)) {
  73                                         printf("SCHED: Warning, do_noquantum "
  74                                                 "failed with %d\n", rv);
  75                                 }
  76                                 continue; /* Don't reply */
  77                         }
  78                         else {
  79                                 printf("SCHED: process %d faked "
  80                                         "SCHEDULING_NO_QUANTUM message!\n",
  81                                                 who_e);
  82                                 result = EPERM;
  83                         }
  84                         break;
  85                 default:
  86                         result = no_sys(who_e, call_nr);
  87                 }
  88
  89                 /* Send reply. */
  90                 if (result != SUSPEND) {
  91                         m_in.m_type = result;           /* build reply message */
  92                         reply(who_e, &m_in);            /* send it away */
  93                 }
  94         }
  95         return(OK);
  96 }
  97
  98 /*===========================================================================*
  99  *                              reply                                        *
 100  *===========================================================================*/
 101 static void reply(endpoint_t who_e, message *m_ptr)
 102 {
 103         int s = ipc_send(who_e, m_ptr);    /* send the message */
 104         if (OK != s)
 105                 printf("SCHED: unable to send reply to %d: %d\n", who_e, s);
 106 }
 107
 108 /*===========================================================================*
 109  *                             sef_local_startup                             *
 110  *===========================================================================*/
 111 static void sef_local_startup(void)
 112 {
 113         /* Register init callbacks. */
 114         sef_setcb_init_fresh(sef_cb_init_fresh);
 115         sef_setcb_init_restart(SEF_CB_INIT_RESTART_STATEFUL);
 116
 117         /* No signal callbacks for now. */
 118
 119         /* Let SEF perform startup. */
 120         sef_startup();
 121 }
 122
 123 /*===========================================================================*
 124  *                          sef_cb_init_fresh                                *
 125  *===========================================================================*/
 126 static int sef_cb_init_fresh(int UNUSED(type), sef_init_info_t *UNUSED(info))
 127 {
 128         int s;
 129
 130         if (OK != (s=sys_getmachine(&machine)))
 131                 panic("couldn't get machine info: %d", s);
 132         /* Initialize scheduling timers, used for running balance_queues */
 133         init_scheduling();
 134
 135         return(OK);
 136 }
 137