The following is an example of the modcalls.d oneliner,


Here we run it for a few seconds then hit Ctrl-C,

   # modcalls.d
   dtrace: script './modcalls.d' matched 18437 probes
   ^C
   
     ptm                                                               2
     mntfs                                                             2
     pool                                                              2
     kcf                                                               4
     pts                                                               5
     portfs                                                            6
     pset                                                              6
     ttcompat                                                          9
     ptem                                                              9
     devfs                                                            13
     ipf                                                              15
     namefs                                                           20
     ctfs                                                             22
     procfs                                                           22
     ldterm                                                           23
     ipgpc                                                            48
     sockfs                                                           58
     flowacct                                                         69
     ata                                                              70
     gld                                                              75
     rtls                                                             76
     specfs                                                           83
     ip                                                              201
     uhci                                                            294
     TS                                                              333
     tmpfs                                                           694
     doorfs                                                          897
     ufs                                                            1329
     uppc                                                           5617
     unix                                                          49794
     genunix                                                       53445

The output lists kernel modules, and the number of function calls for
each module. For example, "rtls" - the network driver, called 76 functions.

This script may be useful to determine whether drivers are "thinking" when
troubleshooting driver issues.