1 02/27/85 response_meters
  2 
  3 Syntax as a command:  response_meters {-control_args}
  4 
  5 
  6 Function:  displays statistics on interactive response time.
  7 
  8 
  9 Control arguments:
 10 -report_reset, -rr
 11    generates a report and then performs the reset operation.
 12 -reset, -rs
 13    resets the metering interval for the invoking process so that the
 14    interval begins at the last call with -reset specified.  If -reset
 15    has never been given in the process, it is equivalent to having been
 16    specified at system initialization time.
 17 -total, -totals, -tt
 18    prints summary information for all work classes.
 19 -work_class N, -wc N
 20    prints information only for work class number N.
 21 
 22 
 23 Access required:  This command requires access to phcs_ or
 24 metering_gate_.
 25 
 26 
 27 Notes:  If neither -reset nor -report_reset is specified,
 28 response_meters prints a report.
 29 
 30 The control arguments -total and -work_class cannot be used together.
 31 If either of these is used, the remaining control arguments must be
 32 such that response_meters prints a report.
 33 
 34 
 35 The fundamental concept needed to understand the output produced by the
 36 response_meters command is that of a terminal interaction.  A terminal
 37 interaction is essentially an atomic unit of work by a Multics user at
 38 a remote terminal.  A terminal interaction is triggered by a set of
 39 characters keyed by a user at a terminal, which are passed into the
 40 user ring as a unit.  The activity between the receipt of the set of
 41 characters at the Multics mainframe and the next request by user-ring
 42 software for more input is a terminal interaction.  For a typical user,
 43 a terminal interaction corresponds to a line of input.  Some user-ring
 44 software, however, receives input as sets of characters rather than as
 45 lines (the Emacs editor is an example of such software).  For software
 46 of this sort, a terminal interaction corresponds to the set of
 47 characters handed out by ring 0 TTY software at one time.  If, in
 48 processing a set of characters keyed by a user at a terminal, the
 49 user-ring software blocks itself on anything other than terminal input,
 50 that activity is not considered a terminal interaction.  For example,
 51 any command that results in tape I/O is not considered a terminal
 52 interaction.
 53 
 54 
 55 The output of response_meters is summarized by work class.  Any work
 56 class for which no interactions were measured is not displayed.  The
 57 following are brief descriptions of the variables printed out by
 58 response_meters for each work class and for the system.
 59 WC
 60    is the work class number.  Work class "All" represents statistics
 61    for the entire system.
 62 # Thinks
 63    is the number of times a process in the work class blocked itself
 64    awaiting terminal input.  The term "Think" is used because the delay
 65    represented here corresponds to what is commonly called "Think Time"
 66    in models of interactive computer systems.  This term is derived
 67    from the assumption that during this time the interactive user is
 68    cogitating about the response just received and is formulating an
 69    appropriate next input.
 70 
 71 
 72 Avg Thinks
 73    is the average time in seconds for all blocks awaiting terminal
 74    input.  This is the average external delay between interactions to
 75    the same process in the work class.  This external delay includes
 76    communications processing time (in the FNP), communications line
 77    delay, and user idle (or "Think") time.
 78 # Queues
 79    is the number of times a process in the work class was queued for
 80    eligibility following receipt of terminal input.  It may be less
 81    than the number of interactions because of type-ahead.  That is, by
 82    keying input sufficiently rapidly, a user may cause several
 83    interactions to be processed during the same eligibility period.  It
 84    may be larger than the number of Thinks because of perturbations
 85    associated with process initiation.
 86 
 87 
 88 Avg Queues
 89    is the average eligibility queue time (in seconds) following the
 90    receipt of terminal input.  This is the average clock time between
 91    the receipt of the terminal input at the Multics mainframe and the
 92    awarding of eligibility to the target process by traffic control.
 93    The average queue time corresponds to what is called "response time"
 94    in the output of traffic_control_meters.
 95 Load Control Group
 96    is the set of Load Control Groups corresponding to the work class.
 97    Read access to the Answer Table and to the Master Group Table (MGT)
 98    is required for this information to be displayed.  If the requesting
 99    process does not have this access, then this field is left blank.
100 
101 
102 Response times by VCPU Range
103    Up to four detail lines and one summary line are printed, with each
104    line corresponding to a set of interactions.  Each interaction
105    measured is categorized by the amount of virtual CPU time consumed
106    by the interaction.  Based on the virtual CPU time for the
107    interaction, the interaction is recorded against one of four
108    "buckets."  Each of the detail lines represents all terminal
109    interactions for processes in the work class that fell into the
110    corresponding "bucket."  A bucket is simply a range of virtual
111    times.  Intuitively, the first bucket represents trivial
112    interactions, the last bucket represents exceptionally long
113    interactions, and the remaining two buckets lie between these
114    extremes.  If there were no interactions recorded against a bucket,
115    the detail line corresponding to that bucket is not printed.  The
116    summary line contains information on all terminal interactions for
117    processes in the work class.
118 
119 
120 VCPU Range
121      From
122      To
123    is the range of virtual CPU times for interactions presented on that
124    line, in seconds.  "From" is the beginning of the range, and "To" is
125    the end of the range.  The summary line is identified by "-----" in
126    both the "From" and the "To" fields.
127 # Int
128    is the number of interactions in the bucket for the line.  That is,
129    this is the number of interactions whose virtual CPU time fell
130    between the values of "From" and "To."
131 Avg VCPU
132    is the average virtual CPU time per interaction for the bucket.
133 
134 
135 Avg RT
136    is the average response time per interaction for the bucket.  It is
137    the average clock time required to process an interaction, including
138    any eligibility queue time.
139 Resp Fact
140    is the response factor.  This is defined as the ratio of the average
141    response time per interaction to the average virtual CPU time per
142    interaction.  Intuitively, this ratio represents an "extension
143    factor" for virtual CPU time.  That is, it is a factor expressing
144    the average amount of clock time required to process an interaction
145    with a given virtual CPU time.  This number can be used as a "quick"
146    indicator of work class or system performance.
147 
148 
149 In addition to the per-work class data described above, the following
150 summary information is displayed.
151 calls to meter_response_time
152    is the number of subroutine calls to the ring 0 routine that
153    collects the raw response time data.
154 invalid transitions
155    is the number of invalid calls to this routine; meter_response_time
156    implements a finite-state automaton that models a terminal user's
157    interaction with the Multics system.  The number of invalid
158    transitions is the number of events that did not fit into this
159    models.  Typically, invalid transitions result from perturbations
160    associated with process initiation.
161 Overhead
162    is the CPU time consumed by the measurement routine, expressed as a
163    percentage of total system CPU time, and as the average CPU time in
164    milliseconds per call to this routine.