DISPLAY ERABLE PERFORlt r , ISPOOLI ITAPE I IALL I L .J
displays the status of the pertinent Vlt/370 ltonitor variables and the status of the internal trace table. SPOO!. is the default operand.
class of monitor is listed.
Regardless of the oFerand you select, each
call and its current enabled/disabled state
If SPOOL is specified, the automatic monitoring specifications
are listed, including whether or not automatic monitoring has
been requested, its start and stop times, the number of
monitor buffers to be used, the userid of the virtual machine to receive the spool file, the spool file record liait and
class, and which classes of monitoring are to be enabled.
If automatic monitoring is already in progress, the spool file
nuaber is given together with the number of monitor buffer
records already written to it.
If the TAPE option is requested, only the status of .onitor
classes and CPTRACE table is indicated.
If ALL is specified, a combination of SPOOL and TAPE responses
is given. enables the specified classes of !ONITOR CALL. Each
successful coapletion of this command creates a new value for
control register 8. The effect of the MONITOR ENABLE command varies, depending on whether data collection is active or
inactive when the co.mand is issued. If data collection is
active, the new mask is moved directly into control register
8, replacing the previous mask, and the new aask takes effect
imaediately. Collection then continues the classes just
entered. If data collection is not active, the new mask is
saved, and data collection of the specified classes does not begin until a ItOB:tTOR START is issued. samples systea resource usage data by accessing system
counters of interest to system performance analysts. RESPONSE collects data on terainal I/O. Simplifies analysis of co.aand
usage, user response time, and system response time. It can
relate user activity to system performance. This class is
invalid and no data can be collected for it unless the system program.er changes the LOCAL COpy file and reassembles D!K!CC. SCHEDULE collects data about scheduler queue manipulation. ltonitors flow of work througb the system
6 and indicates the
resource allocation strategies of the scheduler, which is one
of the key functions of the system. USER periodically scans the chain of V!BLOKs in the system, and
extracts user resource utilization and status data. lISTSI! records every virtual aachine privileged instruction handled by the control program (CP). Because siaulation of privileged
instructions is a major source of overhead, this data may lead
to aethods of iaproving performance. If the VltA feature is
96 V8/370 Operator's Guide

DASTAP SEEKS SYSPROF active, the number of privileged instructions handled by the
control program are reduced for those virtual machines that
are running with the feature activated.
'periodically sa.ples device I/O activity counts (SIO), for
tape and DASD devices only.
collects data for every I/O request to DASD devices. Reveals
channel, control unit, or device contention and arm .ove.ent
interference proble.s. No meaningful inforaation is extracted for V=R regions
if SET NOTRANS is in effect.
adds to the DASTAP and SCHEDULE detailed nprofile
n
of system examination of DASD utilization.
classes to
performance
support a more through closer • Every MONITOR ENABLE command yields a new .ask. Thus, for example, if PERFORM and USER classes are currently being collected and you enter MONITOR ENABLE INSTSIM, then PERFORM. and USER classes are
stopped and INSTSIM is started. • The DASTAP operand in the MONITOR ENABLE co.mand .ust be specified
prior to the MONITOR START TAPE com.and. DASTAP may be disabled at
any time by respecifying the MONITOR ENABLE command with DASTAP absent from the class list. • The SYSPROF class cannot be activated unless both the D1ST1P and SCHEDULE classes are also active. • If data collection is in progress when you issue a BONITOR EIABLE command and CP detects an error in the coa.and line, no change is made to the monitoring status. Unrecognizable keywords and
conflicting operands generate appropriate error .essages. If you do
not specify operands, an error aessage results. r , INTERVAL nnnnn ISECI mm IMINI L Use this operand if a class that involves collecting data at
periodic intervals is enabled or will be enabled, and if you
want to override the default intervals of 60 seconds and 2
seconds. The 60 second interval can be considered as the priaary sampling interval. It deteraines the frequency ,with which the PERFORM, USER and DAST1P classes of monitor are collacted.' The two second interval applies to the
high-frequency data sampling routine. This routine collects
utilization statistics froa the I/O (channels,
control units, and devices) when the DAST1P class' ··is enab led.
The value specified by nnnnn is the interval between data
collections. If you give no interval on the MONITOR INTERVAL command, an error aessage occurs. Either SEC or MIN may follow nnnnn to specify whether nnnnn represents seconds or
minutes. If you give an interval but enter neither SEC nor MIN, the default is SEC. The aaxiau. allowable interval is
nine hours (540 ainutes or 32,400 seconds). The a1n1aua is
five seconds. If no interval is specified in nnnnn, an error
message occurs. The.. field is used to change the collection
interval for the high-frequency saapler. This operand applies
to the DASTAP class of data collection only. The default Section 3. CP Coaaands 91