1
4 0 6 0,1 DMKENTTI Data Items Collected Softvare--ana--hardware utilization, contention,
activity counters
Corresponding items for APU VMBLOK user resource consumption and status DASD and tape activity counters
and
-- Entered via TRQBLOK every two seconds (unless specified otherwise
with the MONITOR INTERVAL command). A new TRQBLOK is i.mediately
stacked via a call to DMKSCHST to specify return of control to the
same entry point two seconds later. This subroutine is a high
frequency (relative to the PERFORM, USER, DASTAP sa.pler) I/O status
sampler. All channels are tested for a busy condition with a TCH instruction. All control units and devices are tested for a busy
condition by examining the appropriate CP control blocks. The data
obtained is accumulated for later sampling by the DASTAP class of
data collection in a class 6 (DASTAP) code 2 (I/O status) record.
The subroutine DMKENT62 performs this collection after the standard
class 6 (DASTAP) code 1 record has been collected by MONCOD61 in DMKMONTI. DMKMONMI from DMKPRG after a monitor call in a class currently enabled
(as defined in CR 8 mask) has been executed by CP in supervisor
state. The .onitor call instruction number and code number stored by
the hardware in the PSA are used to index branch tables to reach the
appropriate data collection routines. As necessary, the data is
stored in the monitor I/O buffers before output. Upon completion, control returns to instruction after monitor call.
Class ---1- 0 1
2
3
2 2
3
4
5 0 7 0 8 0 DMKMONPR Begin console read
Console output
End console read
Console sleep User dropped from queue User added to queue User added to eligible list
privileged instruction being simulated SIO for DASD SEEK
Add queue, drop queue more detailed
consuaption data
resource collection subroutines use a common buffer management subroutine to obtain sufficient space in the monitor buffers. When not enough space is available, a switch is made to the next buffer in
the chain and the full buffer is scheduled for output via a CPEXBLOK. I/O is handled by DMKIOSQR if tape is in use, or by DftKftIliO if a
spool file is in use. If data collection gets ahead of buffer output
and all the monitor buffers are filled, a temporary suspension
occurs. DMKMONIO -- Handles normal and abnormal completion of buffer output to disk or
tape. For normal completion, the buffer used for I/O is made available for further data collection; if the next buffer is already
full, its output is immediately scheduled. If a suspension was in
effect, data collection is immediately resumed using the freed
buffer. (RQte: Suspensions should be eliminated by increasing the
buffer allocation, using the MONITOR co.mand or the SYSMON macro.) Special tape conditions that can be handled include end of tape and
permanent error.
1-186 IBM VM/370 System Logic and Problem 1

DMKENTKC via CPEXBLOK at midnight if automatic monitoring to spool
file is in effect and it is required to close out the current file
and continue monitoring with a new file. DMKENT satisfies the
nucleus residency requirements of CPEXBLOK entry point and acts as a
stepping stone to Goes to DMKDSP after successful call to DMKMIAKC. DftKMIAKC ---Sets-up a request to invoke a MONITOR CLOSE command in DMKMCCCL. Executes MONITOR processing. CLOSE command and calls DMKMIACC to co.plete DMKMIACC -- Invoked by the
chain the spool
data reduction MONITOR CLOSE command to close the spool file and
file block to the reader of the virtual machine where is to take place. Starts new spool file if appropriate. DMKENTST via TRQBLOK due to previous determination by automatic
monitoring facilities that a MONITOR START SPOOL command should be
issued. This entry satisfies the need for CP nucleus residency and immediately calls the pageable DMKMIAIN. DMKMIAIN ---Suilds a message buffer containing a MONITOR START SPOOL command and
calls D5KMCCCL. Executes MONITOR START SPOOL command. DMKENTST gives control to DMKDSP after successful execution. DMKENTET ---Entered via TRQBLOK due to previous determination by automatic
monitoring facilities that a MONITOR STOP command should be issued at this time. This entry satisfies the need for CP nucleus residency
and immediately calls the pageable DMKMIAEN. DMKKIAEN -- Bulls a message buffer containing a MONITOR STOP command and calls DMKMCCCL. Executes MONITOR STOP command. DMKENTET gives control to the
dispatcher after successful execution. DMKMIAST ----Entered from DMKCPI when it is determined that automatic monitoring
has been requested via the SISMON macro in DMKSYS and that TRQBLOKs should be queued via calls to DKKSCHST to invoke a MONITOR START SPOOL command and a MONITOR STOP command at specified times in the
future. If monitoring is required to start immediately because the
start time bas passed, a CPEXBLOK is built to give control to DMKENTSC, which invokes the DMKMIAIN mechanism described above.
All other DMKMCC, DMKMNI and DMKMIA entry points are used as a result
of the processing of MONITOR commands or special conditions.
Three Class 0 monitor call codes have been reserved for special
purposes. They are used without actually executing monitor calls, but
as a result of MONITOR command processing. They are:
Class Code ---0- 97-- 98
99
Function Write-header record after MONITOR START co.mand Write trailer record after MONITOR STOP com.and Write suspension record when data collection resumes CP Method of Operation and program Organization 1-187