2.9BSD/usr/man/cat2/rtp.2

RTP(2)              UNIX Programmer's Manual               RTP(2)

NAME
     rtp - make/unmake a real time process

SYNOPSIS
     rtp(flag)

DESCRIPTION
     _R_t_p changes the notion of the current process from that of a
     normal UNIX process to that of a ``real time'' process.  A
     real time process does not compete for system resources in
     the normal manner; instead, a real time process is con-
     sidered locked into physical memory by the swap scheduler
     and receives exclusive use of the central processor from the
     process scheduler whenever the real time process is in a
     executable state.  Furthermore, other processes which previ-
     ously were non-preemptable but had the potential of consum-
     ing relatively large amounts of cpu time are made preempt-
     able by _r_t_p.

     It is the responsibility of the real time process to see to
     it that use of the cpu is relinquished often enough and long
     enough for other normal UNIX processes to run.  For this
     reason only the super-user or members of group 0 are allowed
     to change the mode of a process by _r_t_p.

     The _f_l_a_g argument is set to a non-zero value to make a nor-
     mal process into a real time process.  There can be only one
     real time process active at any moment.

ERRORS
     _R_t_p will fail if:

     [EPERM]             The process's effective user ID is not
                         the super-user and the process's effec-
                         tive group ID is nonzero.

     [EBUSY]             A real time process already exists.

SEE ALSO
     lock(2), nice(2), renice(2)

ASSEMBLER
     (rtp = 49.)
     (flag in r0)
     sys rtp

AUTHOR
     Thomas Ferrin, University of California, San Francisco

Printed 5/22/83                                                 1