i386/ucla/src/lab4/user/fairness.c

   1 // Demonstrate lack of fairness in IPC.
   2 // Start three instances of this program as envs 1, 2, and 3.
   3 // (user/idle is env 0).
   4
   5 #include <inc/lib.h>
   6
   7 asmlinkage void
   8 umain(int argc, char **argv)
   9 {
  10         envid_t who, id;
  11
  12         id = sys_getenvid();
  13
  14         if (thisenv == &envs[1]) {
  15                 while (1) {
  16                         ipc_recv(&who, 0, 0);
  17                         cprintf("%x recv from %x\n", id, who);
  18                 }
  19         } else {
  20                 cprintf("%x loop sending to %x\n", id, envs[1].env_id);
  21                 while (1)
  22                         ipc_send(envs[1].env_id, 0, 0, 0);
  23         }
  24 }