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Program Specification



                    SNOOPY/TATTLE


                    Programs for studying
                    CPU time usage



                    Copyright 1979,1972 by:
                        Digital Equipment Corp.
                        Maynard, Mass.  01754



                    AUTHOR:  Jud Leonard
                    DATE:  May 31, 1972
                    FILE:  SNOOPY.RNO
                    EDITION:  1


The information in this document is subject to change  without  notice
and  should  not  be  construed  as  a  comitment by Digital Equipment
Corporation.  Digital Equipment Corporation assumes no  responsibility
for and errors that may appear in this document.

The software described in this document is furnished under  a  license
and  may  be  used or copied only in accordance with the terms of such
license.

Digital Equipment Corporation assumes no responsibility for the use or
reliability  of  its  software  on  equipment  that is not supplied by
DIGITAL.

     Copyright (C) 1972,1979 by Digital Equipment Corporation

The following are trademarks of Digital Equipment Corporation:

DIGITAL        DECsystem-10   MASSBUS
DEC            DECtape        OMNIBUS
PDP            DIBOL          OS/8
DECUS          EDUSYSTEM      PHA
UNIBUS         FLIP CHIP      RSTS
COMPUTER LABS  FOCAL          RSX
COMTEX         INDAC          TYPESET-8
DDT            LAB-8          TYPESET-10
DECCOMM        DECsystem-20   TYPESET-11
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                          Page 2


1.0 INTRODUCTION SNOOPY is a program which samples the PC  at  regular
time  intervals,  building  a histogram which describes the areas of a
program in which it spent CPU time.  After sampling for  a  period  of
time,  the collected histogram is written as a disk file, for analysis
and listing by the companion program TATTLE.  Options permit SNOOPY to
collect  data on the monitor and/or interrupt service routines for all
jobs on the system, or to collect data on the performance of some  job
or  system  program, including time spent in the monitor servicing the
selected job or cusp.  The sampling frequency may be controlled either
by  the  DK10  real-time  clock, or by the line-frequency clock in the
APR.  The data may be collected for a single period  under  controlled
conditions,  or  SNOOPY  may  be  set  up  to  write  histogram  files
cyclically, so that data may be  collected  over  an  entire  day,  if
desired, without operator intervention.  The resulting histogram files
are given unique extensions, and  may  be  processed  individually  by
TATTLE,  or  combined  as  desired  by  programs written in FORTRAN or
MACRO.

1.1 REQUIREMENTS SNOOPY must lock itself in core,  and  must  use  the
RTTRP  feature  to  work properly.  It must, therefore, be run under a
PPN with LOCK and RTTRP privileges, on a monitor assembled  for  those
features.   In addition, the TRPSET feature and privilege are required
to sample using the APR clock.  While sampling may be  performed  from
the  line-frequency APR clock, it is subject to severe bias due to the
fact that the system scheduling is also syncronized to line frequency.
Results  obtained  with the DK10 real-time clock are more useful, both
because of the bias problem, and because  the  DK10  can  be  made  to
interrupt  much  more  frequently,  thereby  increasing  the number of
samples taken in a  given  time  period,  and  the  precision  of  the
results.

1.2 RESTRICTIONS SNOOPY does oot recognize  dual  processor  (1055  or
1077)  systems.  It does not operate correctly when DK10 accounting is
used, or, for that matter, the DK10 is in use by any other program.
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                          Page 3


2.0 Using SNOOPY Run SNOOPY.  It will ask:

SNOOP ON?(INTERRUPTS, MONITOR, JOB#, CUSP)

Answer with one of the words in parenthesis (first letter will do) and
carriage  return (hereafter abbreviated <CR>).  The sequence from that
point will depend on this answer, which determines the qualifiers  for
entering any sample into the histogram.

2.1 INTERRUPTS This response to the first question means that the user
wants to study the time spent in the monitor during interrupt service,
and ignore any samples taken with no  PI  in  progress.   The  default
histogram file name is set to INTRPT.HST.  The next question is:

PI LEVEL TO WATCH?(2-7 OR *)

The user may respond with any digit between  2  and  7  inclusive,  to
indicate  that  samples are to be taken only when the CPU is servicing
the specified level, or * to indicate that all time in PI  service  is
to be entered into the histogram.  It is not posible to study PI level
1, because the sampling routine must be at a higher priority than  the
program  being  studied,  and 1 is the highest level.  From this point
the questions and answers are  the  same  as  described  in  2.11  and
following, below.

2.2 MONITOR This response to the first question means the  user  wants
to  study  the  time  spent  in the monitor for all jobs.  The default
histogram file name is set to MONITR.HST.  The next question is:

INCLUDE PI TIME?(N,Y)

The user may respond with YES or NO.  The default is NO,  which  means
that the histogram will include time spent in UUO service, but not the
time spent servicing interrupts.  An answer of YES includes  interrupt
service  time  in  the  histogram.   From this point the questions and
answers are the same as 2.11 and following, below.

2.3 JOB# This response to SNOOPY's initial question is used  to  study
the performance of some particular job.  The next question is:

JOB #?

to which the user should respond with the decimal number of the job he
wishes to study.  SNOOPY then asks:

NAME OF CUSP?

The user should respond with the (up to) six  character  name  of  the
cusp  running  in  the  specified  job.  SNOOPY does not use this name
during the sampling process, but saves it in the histogram file as the
default  name  TATTLE  should  use  in looking for a symbol table with
which to list the histogram data.   The  name  is  also  used  as  the
default file name for the histogram file, with the extension .HST From
this point the questions and answers are the same as  those  described
in 2.7 and following, below.
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                          Page 4


2.4 CUSP This response to SNOOPY's initial question indicates that the
histogram  is  to  reflect  the  time  used  by some specified program
whenever it is run by any job.  Program is taken to mean  a  job  with
one  of  the  following combinations:  a named low segment and a named
(possibly different) high segment or no  high  segment,  a  named  low
segment  and  any  or no high segment, or any low segment with a named
high segment.  The next question is:

LOW SEG NAME?(* IF ANY)

The user may type the (up to) six character  name  of  a  low  segment
which  must  match  to  include  a  sample  in  the histogram, or * to
indicate that any low segment  name  is  acceptable.   If  a  name  is
specified, go to 2.6.

2.5 Any low segment If * is specified as the  low  segment  name,  the
next question is:

HIGH SEG NAME?

The user must specify the name of a high segment to match for  samples
to  be  included  in the histogram.  Whenever a job contains the named
high segment,  samples  will  be  taken  on  that  job.   The  default
histogram  file  name is set to the name specified, with the extension
.HST.  From this point, the questions and answers are as described  in
2.8 and following, below.

2.6 Named low segment If an explicit low segment name is given, it  is
stored  as  the  default  histogram file name with extension .HST, and
samples are included in the histogram only for jobs whose low  segment
name matches that given.  The next question is:

HIGH SEGMENT NAME?(CR IF SAME)

The user may type <CR> if the high segment name to be matched  is  the
same  as  the  low  segment  name  given,  *  if  any  high segment is
acceptable, or the name of the only high segment which may be  in  the
job's addressing space for samples to be taken.
NOTE:  A job whose low segment name matches that given, but which  has
no  high  segment,  is  considered  eligible  for sampling, even if an
explicit high segment name was specified.

2.7 Low segment size Whenever a job number or cusp  is  specified  for
snooping, the following questions may be asked:

LOW SEG SIZE IN K?

The user may respond with 0 or just <CR> to indicate that  he  is  not
interested  in  a breakdown of time spent in the low segment (in which
case the questions continue at 2.8), or the size in K  (=1024  decimal
words)  of  the  portion of the low segment starting at relative 0 for
which he wishes to collect samples.  Samples  taken  when  the  PC  is
greater   than  the  specified  limit  will  be  counted  together  as
out-of-range.  If a non-zero size was specified for the  low  segment,
the next question is:
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                          Page 5


LOW SEG RESOLUTION?  2**

The user should answer with a decimal number indicating the number  of
words  in  a  group  which  will be counted together in the histogram.
SNOOPY shifts the low segment size right by this  number  to  get  the
size  of  the  low  segment  histogram.   (One  additional location is
allowed for samples out of range.) The PC is divided by the resolution
when  each  sample  is  taken  to  determine  the table location to be
incremented.

2.8 High segment size If  the  high  segment  name  specified  was  *,
questions continue at 2.9.  Otherwise, the next question is:

HIGH SEG SIZE IN K?

This question is answered in  the  same  way  as  2.7,  above.   If  a
non-zero size is specified, the next question is:

HIGH SEG RESOLUTION?  2**

This question is analogous to the low seg resolution question in  2.7,
above, and is answered in the same way.

2.10 Monitor or UUO breakdown When the size and  resolution  questions
have been answered for a job or cusp, SNOOPY asks:

FULL MONITOR BRKDWN, OR BY UUO?(U,M)

This question allows the user to choose whether the time spent in  the
monitor by a program is broken down by monitor addresses or by the UUO
which invoked the monitor.  If UUO is chosen  (the  default),  monitor
time  spent  for  the job is included in a histogram by UUO code, with
CALLI broken down separately.  The questions continue at 2.13.
NOTE:  Due to the mechanisms by which  re-scheduling  can  take  place
during UUO processing, this option can cause UUO time to be attributed
to a job which did not perform the UUO.  This time will ordinarily  be
small,  but  the  user  should  not  be surprised to see certain UUO's
(particularly HIBER, SLEEP, DAEMON, and I/O UUO's) attributed  to  the
program being watched even though it has no such UUO's.  If MONITOR is
chosen, monitor time spent for the job is broken down by address.
NOTE:  The monitor symbol table is quite large (often  30K  or  more),
and  TATTLE  must  have  it  entirely  in  core  to produce a symbolic
histogram listing.  Obviously, this may  represent  a  restriction  to
users  with small core configurations.  Therefore, TATTLE will produce
a histogram by absolute address only if it is unable to get sufficient
core  for the symbol table, and the user must refer to the load map to
determine symbolic locations.
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                          Page 6


2.11 Monitor size Unless the UUO breakdown option is chosen  in  2.10,
above,  the  following question is asked for any choice on the initial
question:

MONITOR SIZE IN K?

This question is answered in the same  way  as  2.7,  above.   If  the
response is non-zero, the next question is:

MONITOR RESOLUTION?  2**

This question is analogous to the low seg resolution question in  2.7,
above, and is answered in the same way.

2.12 UUO timing If the response to the initial question  was  anything
but  MONITOR,  the  dialog continues at 2.13.  If monitor snooping was
selected, however, the next question is:

WATCH UUO TIMES?(N,Y)

If the user responds NO (the default), time spent in  the  monitor  is
not broken down by UUO.  If the answer is YES, however, a histogram is
built which breaks down monitor time by the UUO being serviced, with a
separate table for CALLI.

2.13 Clock to use The following question will always be asked next:

USE DK10?(N,Y)

If the user's response is NO (the  default),  the  line-frequency  APR
clock  will  be  used  to define the sampling interval, and the dialog
will continue at 2.14 (see note in 1.1).  If the answer  is  YES,  the
next question will be:

INTERVAL IN USEC'S?(200-1000000)

The user must type  a  decimal  number  between  200  and  a  million,
specifying  the  sampling interval in micro-seconds.  The smaller this
number, the more samples will be taken,  but  the  system  performance
will be degraded by the time spent sampling.

2.14 Opcode breakdown The following question gives the user the option
of  analyzing  opcode  usage,  unless  the  sampling is done on a KI10
processor, in which case the dialog continues at 2.15:

WATCH OPCODE USAGE?(N,Y)

If the user answers NO (the default), dialog continues at 2.15.  A YES
response  causes  a histogram of 9-bit opcodes to be built, displaying
the time spent in the watched program by each instruction.

2.15 Histogram file The next question is:

OUTPUT FILE NAME?  DSK:
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                          Page 7


The user may specify a file name  and/or  extension  to  override  the
default (as defined above), or may type <CR> to use the default.

2.16 Cycle time The next question is:

CYCLE TIME?(MINUTES)

The user may type 0 or just <CR> to specify that only one histogram is
to be built, or he may type a decimal number which will be interpreted
as the number of minutes during which SNOOPY  will  sample  before  it
writes a histogram file, clears the tables, and resumes sampling.  The
first file written has the name specified in 2.15, above.  Thereafter,
characters  in  the  extension  are forced numeric, and incremented in
decimal to 999, after which SNOOPY exits.  The user may stop SNOOPY at
any time during a cycling run by typing <CR>.

2.17 Starting sampling SNOOPY will type:

DATA SIZE IS nnnn WORDS.
TYPE COMMENTS<CR> TO GO:

Where nnnn is the (decimal) size of the histogram, and represents  the
minimum  usable  dimension of the array DATA in TATTLE.  Sampling will
begin when the user types <CR>.  Before that, he may enter  up  to  50
characters  of  comments,  which  SNOOPY  will  save  as  part  of the
histogram file to be printed with the listing by TATTLE.  This  allows
the  user  to  note the particular conditions under which the sampling
was done, if any.

2.18 Stopping SNOOPY SNOOPY will type:

TYPE <CR> TO STOP:

The user may type <CR> at any time to stop sampling and exit.   SNOOPY
will write the histogram file to disk, and type:

HISTOGRAM FILE file.ext WRITTEN
WITH nn/mm SAMPLES.

where mm is the total number of interrupts taken, and nn is the  total
number  of samples included in the histogram.  This message is printed
each time SNOOPY writes a file,  whether  in  single  or  cycle  mode.
Typing  ^C's  while  SNOOPY  is  sampling  will  stop sampling without
writing a histogram.  This is intended  as  an  emergency  abort,  and
should not be used under ordinary circumstances.
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                          Page 8


2.19 SNOOPY errors The following error messages may  be  generated  by
SNOOPY:

    ?TRAP LOC NOT A JSR
            Attempting to setup for the APR clock, the  trap  location
            for  the  APR  channel  was not a JSR instruction.  Should
            never happen.
    ?CANT DO TRPSET
            The TRPSET UUO gave an  error  return,  indicating  either
            that  the  user  did  not  have  TRPSET privileges, or the
            monitor did not include the TRPSET feature.
    ?TRAP LOC CHANGED!!
            Should never happen.  The location  on  which  TRPSET  was
            done has changed during setup.
    ?CANT RESTART TIMESHARING
            Should never happen.  SNOOPY was unable  to  restart  time
            sharing after the TRPSET UUO.
    ?CANT START DK10
            Probably indicates there is no DK10 clock on  the  system.
            After  attempting  to  start  it, SNOOPY found the run bit
            off.
    ?CANT INIT DISK
            When trying to write the  histogram  file,  the  INIT  UUO
            failed.
    ?  ENTER FAILURE ON name.ext
            The ENTER UUO failed  while  trying  to  write  the  named
            histogram file.
    SHUT DOWN
            SNOOPY has trapped a monitor-detected  error  or  ^C,  and
            disabled  the  interrupt  code.   SNOOPY  exits to monitor
            mode.
    ?SORRY, NEED PRIVILEGES
            SNOOPY was run under a PPN without real-time trap and lock
            privileges.
    ?x UNKNOWN
            The response "x"  is  not  recognized  as  valid  for  the
            question.
    ?CANT GET JBTPRG
            GETTAB returned an  error  while  attempting  to  get  the
            address of the monitor table JBTPRG.
    ?CANT GET JBTSGN
            Same as above, except JBTSGN table.
    ?CANT GET JBTADR
            Same as above.
    ?CANT GET CORE
            SNOOPY was unable to get  sufficient  core  to  build  the
            histogram tables.
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                          Page 9


            ?CANT LOCK
            The LOCK UUO gave an error return.
    ?CANT GET USER IO MODE
            An RTTRP UUO which attempted to get user I/O mode  failed.
            Probably  indicates  that  the  monitor  does not have the
            RTTRP feature.
    ?  APR PRIORITY TOO LOW
            The APR clock is assigned  to  a  lower  priority  (higher
            channel number) than the interrupt channel to be watched.
    ?  APR CLOCK UNASSIGNED
            Should never happen.  The conditions read by a  CONI  APR,
            returned a PI assignment of zero.
    ?CANT GET A CHANNEL
            SNOOPY was unable to place  itself  on  a  appropriate  PI
            channel by using the RTTRP UUO.
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                         Page 10


    3.0 Using TATTLE TATTLE requires a symbol table for  each  program
    on which SNOOPY did a PC breakdown in expanded save (.XPN) format.
    For the  monitor,  this  usually  exists  as  SYS:SYSTEM.XPN.   An
    appropriate  file  can  be  created  for any cusp by the following
    command sequence, where "cusp" represents the name of the cusp:

    LOAD %S%B cusp ;INCLUDE ANY NECESSARY SUBROUTINES
    SAVE cusp
    R FILEX
    cusp.XPN_cusp.SAV ;USE .LOW INSTEAD OF .SAV
                      ;IF 2-SEG PROGRAM

    3.1 Running TATTLE When expanded files have been created for  each
    cusp on which snooping was done, assign LPT:  or spool it, and run
    TATTLE.  It will ask:

    HISTOGRAM FILE:

    The user should respond  with  the  name  of  the  histogram  file
    written  by  SNOOPY  (defaults  are  DSK:MONITR.HST).  TATTLE will
    print the symbolic histogram listing, and return to the  question.
    When all desired files have been processed, type <CR> to return to
    monitor mode.
PROGRAM SPECIFICATION -- SNOOPY/TATTLE                         Page 11


    3.2 TATTLE Errors The following error messages may be  printed  by
    TATTLE:

    ?CANT INIT
    HISTOGRAM FILE:
            The  INIT  UUO  failed  when  TATTLE  tried  to  read  the
            histogram file.
    ?CANT LOOKUP
    HISTOGRAM FILE:
            The LOOKUP UUO  failed  when  TATTLE  tried  to  read  the
            histogram file.  Type the device, filename, extension, and
            PPN of the histogram file.
    ?CANT INIT dev
    WHERE IS EXPANDED FILE?
            The INIT UUO failed when TATTLE was  trying  to  read  the
            symbol   table.   Type  the  file  specification  for  the
            expanded file containing the symbol table, or <CR> to list
            the histogram without symbols.
    ?LOOKUP FAILURE ON dev:file.ext
    WHERE IS EXPANDED FILE?
            The LOOKUP UUO failed when TATTLE tried to read the symbol
            table.  Respond as above.
    ?CANT FIND SYMBOL TABLE IN dev:file.ext
    WHERE IS EXPANDED FILE?
            The file in which TATTLE expected to find the symbol table
            does not have one.  Respond as above.
    ?INSUFFICIENT CORE TO READ dev:file.ext SYMBOL TABLE
            The symbol table of the specified file is too big  to  fit
            in  the  available  core.   The  listing  of the histogram
            continues without symbols.
    HISTOGRAM FILE FORMAT IS INCORRECT
            The specified histogram file is not in the proper  format.
            This  may  be  due  to  different  versions  of SNOOPY and
            TATTLE, or may be caused by specifying the wrong  file  to
            TATTLE.
    HISTOGRAM FILE IS TOO BIG.  ENLARGE DATA TO nnnn
            The histogram file is larger than  the  space  allowed  in
            TATTLE  for it.  Change the dimension of the array DATA in
            TATTLE to at least the number  given.   (also  change  the
            call to RHIST at statement 100, and the IF statement about
            14 lines below it.)

    [END OF SNOOPY.DOC]