IMPTRACE(1)                  General Commands Manual                 IMPTRACE(1)

     imptrace – report importance donation events in real time

     imptrace [-i [-s]] [-p pid] [-d]

     The imptrace utility displays a trace of importance donation events.
     Importance donation is used by adaptive jobs on the system to manage their
     priority on the system. See xpc_transaction_begin(3) and launchd.plist(5)
     for more information about the mechanism and its use.

     The options are as follows:

     -i       Show internal kernel boosts

     -s       Show stacks for internal boosts.

     -p pid   Limit events to the process identified by pid.

     -d       Display raw Dtrace output; do not reformat timestamps and sort

     The traced events are as follows:

     BOOSTED         The specified process has received a boost and transitioned
                     out of the background.

     UNBOOST         The specified process has dropped its last remaining boost
                     and transitioned back into the background.

     Recv Boost      The specified process has received a boost and accepted
                     ownership of that boost in userspace, usually by dequeuing
                     the boosting message.

     Drop Boost      The specified process has dropped a boost.

     ____ Int Boost  Internal boost events are only emitted when tracking of
                     kernel internal boosts is activated with the -i option.
                     Their use and meaning is subject to change and dependent on
                     the implementation details of importance donation.

     The imptrace script will output one line for each event, for example a
     typical boosting exchange might look as follows:

           0000:00:00.000000000 EVENT            PROCESS                BOOSTS NOTES
           0023:15:13.844332886   BOOSTED            22:configd
           0023:15:13.844372519   Recv Boost         22:configd              1 from    275:SystemUIServer
           0023:15:13.844497860   UNBOOST            22:configd                Boosted for 0 ms
           0023:15:13.844509452   Drop Boost         22:configd              0

     In this case, SystemUIServer (PID 275) has sent a message to configd (PID
     22) which caused it to be boosted. configd then dropped the boost causing
     it to be become unboosted and return to background state. Boosted and
     unboost events may appear before the triggering recv or drop boost.

     imptrace is implemented using Dtrace.  For information about the probes
     used, see comments in the imptrace source.  When debugging an adaptive
     service, it may be helpful to combine these probes with other Dtrace
     providers; however, they should be considered unstable.

OS X                               May 1, 2013                              OS X