
Submitted by:	Robert Nance
		Johnson Controls Inc., Special Systems Operation
		9550 Ridgehaven Ct.
		San Diego, CA	92123

Description:	Probe is a system performance measuring tool. It indicates the 
amount of time being spent in interrupt processing, kernel space processing, 
user space processing, and null time. In addition, it provides some subroutine 
time histogramming for an adjustable number of (FORTRAN usually) tasks by 
taking advantage of the exit traceback information provided by the OTS. It is 
intended for use on a CRT, and is presently set for a VT100.

System reqts:	During Probe's execution, I found that Probe introduces about 
5% overhead in CPU time. If it is changed to update the screen less often, 
this will be lessened. Its size is adjustable, it is set up for about 2KW.
It is driven by system clock interrupts, and can easily be changed to be 
compatible with any such interrupt. It uses memory management hardware address 
directly - It should not be too difficult to change it if, for some reason, 
its use on systems without this hardware. In its present configuration it uses 
one global event flag.

Documentation:	PROBE.DOC describes the output format and some uses,
and the source is well commented (I hope).

Status:		A possibly dangerous tool in the hands of fiddlers. If aborted 
when not in stasis mode it will leave some of the pool space permenently 
allocated. It is run at extremely high priority to prevent races, as it pokes 
around in the pool space and the memory management hardware to retrieve the 
subroutine histogramming information.

Desired enhancements:	The ability to better pick which tasks are 
histogrammed. Data buffering storage changable based on task size extension at 
install time.

Support:	The author welcomes comments & suggestions, but does not
want complaints, although will be interested in fixes to eliminate same. I do 
not yet know for certain how compatible it will be with RSX v4.0 or the new 
Fortran, but will myself make any necessary conversions, and will share any 
such changes, if any, when they are available.

