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
  16 struct machine machine;         /* machine info */
  17
  18 /*===========================================================================*
  19  *                              main                                         *
  20  *===========================================================================*/
  21 int main(void)
  22 {
  23         /* Main routine of the scheduler. */
  24         message m_in;   /* the incoming message itself is kept here. */
  25         int call_nr;    /* system call number */
  26         int who_e;      /* caller's endpoint */
  27         int result;     /* result to system call */
  28         int rv;
  29         int s;
  30
  31         /* SEF local startup. */
  32         sef_local_startup();
  33
  34         if (OK != (s=sys_getmachine(&machine)))
  35                 panic("couldn't get machine info: %d", s);
  36         /* Initialize scheduling timers, used for running balance_queues */
  37         init_scheduling();
  38
  39         /* This is SCHED's main loop - get work and do it, forever and forever. */
  40         while (TRUE) {
  41                 int ipc_status;
  42
  43                 /* Wait for the next message and extract useful information from it. */
  44                 if (sef_receive_status(ANY, &m_in, &ipc_status) != OK)
  45                         panic("SCHED sef_receive error");
  46                 who_e = m_in.m_source;  /* who sent the message */
  47                 call_nr = m_in.m_type;  /* system call number */
  48
  49                 /* Check for system notifications first. Special cases. */
  50                 if (is_ipc_notify(ipc_status)) {
  51                         switch(who_e) {
  52                                 case CLOCK:
  53                                         expire_timers(m_in.NOTIFY_TIMESTAMP);
  54                                         continue;       /* don't reply */
  55                                 default :
  56                                         result = ENOSYS;
  57                         }
  58
  59                         goto sendreply;
  60                 }
  61
  62                 switch(call_nr) {
  63                 case SCHEDULING_INHERIT:
  64                 case SCHEDULING_START:
  65                         result = do_start_scheduling(&m_in);
  66                         break;
  67                 case SCHEDULING_STOP:
  68                         result = do_stop_scheduling(&m_in);
  69                         break;
  70                 case SCHEDULING_SET_NICE:
  71                         result = do_nice(&m_in);
  72                         break;
  73                 case SCHEDULING_NO_QUANTUM:
  74                         /* This message was sent from the kernel, don't reply */
  75                         if (IPC_STATUS_FLAGS_TEST(ipc_status,
  76                                 IPC_FLG_MSG_FROM_KERNEL)) {
  77                                 if ((rv = do_noquantum(&m_in)) != (OK)) {
  78                                         printf("SCHED: Warning, do_noquantum "
  79                                                 "failed with %d\n", rv);
  80                                 }
  81                                 continue; /* Don't reply */
  82                         }
  83                         else {
  84                                 printf("SCHED: process %d faked "
  85                                         "SCHEDULING_NO_QUANTUM message!\n",
  86                                                 who_e);
  87                                 result = EPERM;
  88                         }
  89                         break;
  90                 default:
  91                         result = no_sys(who_e, call_nr);
  92                 }
  93
  94 sendreply:
  95                 /* Send reply. */
  96                 if (result != SUSPEND) {
  97                         m_in.m_type = result;           /* build reply message */
  98                         reply(who_e, &m_in);            /* send it away */
  99                 }
 100         }
 101         return(OK);
 102 }
 103
 104 /*===========================================================================*
 105  *                              reply                                        *
 106  *===========================================================================*/
 107 static void reply(endpoint_t who_e, message *m_ptr)
 108 {
 109         int s = send(who_e, m_ptr);    /* send the message */
 110         if (OK != s)
 111                 printf("SCHED: unable to send reply to %d: %d\n", who_e, s);
 112 }
 113
 114 /*===========================================================================*
 115  *                             sef_local_startup                             *
 116  *===========================================================================*/
 117 static void sef_local_startup(void)
 118 {
 119         /* No init callbacks for now. */
 120         /* No live update support for now. */
 121         /* No signal callbacks for now. */
 122
 123         /* Let SEF perform startup. */
 124         sef_startup();
 125 }