Subject:   -41- 1.2 libpf Phase toggling overlapped cull and draw
Date: 8 Apr 1994 00:00:01 EST

  When running in the PFMP_CULLoDRAW multiprocessing mode, changing the
  phase from PFPHASE_LOCK or PFPHASE_FLOAT to PFPHASE_FREE_RUN or
  PFPHASE_LIMIT can cause the application to deadlock.

  In perfly, rapidly toggling the phase when running with the
  PFMP_CULLoDRAW multiprocessing model ("perfly -m 65540" or "perfly -m
  65542") can cause the application to hang.

  Workaround: toggle only once every few frames or not at all.