IMPTRACE(1)						    BSD General Commands Manual 					       IMPTRACE(1)

NAME

     imptrace -- report importance donation events in real time

SYNOPSIS

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

DESCRIPTION

     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 output.

     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 boost-
		     ing 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.

EXAMPLES

     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.

NOTES

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

OS X
								   May 01, 2013 							      OS X