(1)	INTRODUCTION

	In order to discover where bru spends most of its time, and
	how inclusion of the macro based debugger package (dbug)
	affects execution, a version of bru, both with and without
	inclusion of the debugger, was profiled and the results are
	presented here.

	First some information about the machine and the version of
	bru used:

		Bru version:		4.8
		Machine:		Callan Unistar 200
		Cpu:			68000
		Cpu clock:		8 Mhz
		Wait states:		2
		Archive device:		MPI 8304 (640Kb floppy)
		Archive size:		272Kb
		Files in archive:	32


(2)	TIMING TESTS

	The raw statistics from timing execution with the "time" command
	are:

		No dbug				With dbug
	
	Mode	Real	User	Sys		Real	User	Sys
	----	-----------------------		-----------------------

	c	1:05.8	3.9	2.4		1:08.7	7.4	2.7
	d	1:15.1	5.0	4.6		1:19.7	10.0	4.5
	e	6.4	0.7	2.9		7.6	1.2	2.9
	i	1:00.9	3.8	2.2		1:04.9	7.4	2.3
	t	31.5	2.8	3.9		33.1	4.9	4.2
	x	1:15.9	3.9	6.0		1:16.5	8.5	5.8


(3)	PROFILING TESTS

	The profiling tests were run using the system V "prof" facility.
	The following table represents at least the top 10 functions
	for every mode (since they are not always the same ones the
	table contains more than 10 entries).
	

			Percent time spent in the function
			(dbug package used)

	Function	  c       d       e       i       t       x
	--------	-----   -----   -----   -----   -----   -----
	
	__doprnt	22.55    5.73   14.43    7.60    7.09    5.59
	 _chksum	19.57   37.16    0.00   49.54   25.59   42.57
	   _diff	 0.00   19.27    0.00    0.00    0.00    0.00
	_zeroblk	10.07    0.00    0.00    0.00    0.00    0.00
	   aldiv	 6.10    0.69    2.32    0.61    1.18    0.25
	    lrem	 5.11    0.46    3.61    0.00    9.06    0.25
	 _memcpy	 3.26    0.92    1.55    1.82    0.79    0.25
	  mcount	 2.55    0.23    1.29    0.61    1.57    2.02
	_sprintf	 2.13    0.00    0.00    1.22    0.39    0.00
	_fromhex	 0.00    2.52    0.00    3.04    4.33    2.02
	    smul	 0.43    0.92    0.52    0.30    0.00    0.76
	_tree_wa	 0.14    0.00    3.87    0.00    0.00    0.00
	 _fwrite	 1.13    0.46    3.87    0.91    2.36    0.76
	__flsbuf	 0.00    0.46    3.09    0.00    2.36    0.76
	    ldiv	 0.43    0.46    2.58    0.00    1.57    0.76
	  _tohex	 1.99    0.46    0.00    1.22    0.79    0.50
	_memccpy	 0.14    0.46    0.26    0.30    2.76    0.50
	_ar_seek	 0.57    0.69    0.00    0.91    0.39    1.26
	_ar_read	 0.00    0.46    0.00    0.61    0.00    1.01

					(debugger functions)

	__db_key	 5.25   10.09   19.33   11.85   13.78   16.62
	__db_pri	 1.42    1.83    3.35    2.74    2.36    3.37
	__db_ent	 1.56    5.05    7.22    3.04    4.72    4.03
	__db_ret	 3.26    4.59    8.25    2.13    4.72    3.27




			Percent time spent in the function
			(dbug package not used)

	Function	  c       d       e       i       t       x
	--------	-----   -----   -----   -----   -----   -----
	
	__doprnt	31.91    5.86   29.18   10.90    9.44    8.02
	 _chksum	22.27   53.52    0.00   65.88   37.22   61.79
	   aldiv	 8.35    0.39    6.01    0.95    1.11    0.94
	_zeroblk	 6.85    0.00    0.00    0.00    0.00    0.00
	    lrem	 4.71    0.39    1.72    0.47   15.56    0.00
	 _memcpy	 3.85    1.17    2.58    1.42    1.67    1.89
	  _sleep	 2.14    0.78    0.43    0.00    0.00    0.00
	  mcount	 2.14    0.00    2.58    1.42    2.78    0.94
	  _tohex	 1.71    0.39    0.00    0.00    0.00    0.47
	_sprintf	 1.71    0.00    0.00    0.47    0.56    1.42
	   _diff	 0.00   23.05    0.00    0.00    0.00    0.00
	_s_fprin	 0.43    5.86    0.00    0.95    2.22    0.00
	_fromhex	 0.00    1.56    0.00    5.21    3.33    6.60
	_verbosi	 0.43    1.17    0.86    0.95    0.00    0.47
	__flsbuf	 0.46    1.17    4.29    0.00    2.22    0.94
	__xflsbu	 0.21    0.78    3.86    0.95    0.00    0.00
	_ar_seek	 0.21    0.78    0.00    0.00    1.67    0.00
	    ldiv	 0.21    0.78    6.44    0.95    1.67    0.94
	_tree_wa	 0.21    0.00    3.86    0.47    0.00    0.00
	 _fwrite	 1.07    0.39    3.43    0.95    1.11    0.94
	    smul	 1.07    0.78    3.00    0.95    1.11    1.89
	_estimat	 0.00    0.00    2.58    0.00    0.00    0.00
	_endpwen	 0.00    0.00    0.00    0.95    1.11    0.00
	 _gmtime	 0.00    0.00    0.00    0.00    2.22    0.00
	__cleanu	 0.00    0.00    1.72    0.47    1.67    0.00
	_s_signa	 0.00    0.00    0.00    0.00    1.42    1.42
	  _write	 0.43    0.00    1.72    0.47    1.42    1.42


(4)	CONCLUSIONS


	1.	Because the elapsed (real) time is so much larger
		than the sum of the user and system times, bru
		appears to be mostly I/O bound.  Thus performance
		will be highly dependent upon the speed of the
		peripherals used as the archive device.

	2.	Because bru is I/O bound, inclusion of the debugger
		does not significantly effect total execution time.
		However, note that approximately 10-30 percent of
		the time spent executing user code is spent in the
		debugger routines.  Thus in a multiuser environment,
		inclusion of the debugger adds significant cpu
		burden to the system.

	3.	Depending upon mode, bru spends from 20-60 percent of
		its time computing block checksums in the routine
		"chksum".  It might be worthwhile to recode this
		particular routine is assembly language for a
		specific implementation in a multiuser
		or multiprocessing environment.  If bru is used
		mostly on a system in "single-user" mode and
		is the only significant process running, there is
		probably no performance advantage to be gained by
		recoding chksum since bru is I/O bound anyway.