Monitoring I/O for application program DL/I Calls
The IMS Monitor report shows the total number of I/O occurrences and the total time the occurrences took for each application program executed during a monitored interval.
The Program-I/O report gives these two totals for all PSBs active during the monitored interval and includes the detailed breakdown of the I/O wait time as it was incurred by each PCB used by the program.
The report shows any contention experienced during application program processing. Each type of conflict and the number of times it occurred are recorded for each I/O PCB or database PCB. The report shows the total wait time, the highest wait experienced, and the average time. Subtotals are given for each PCB under a PSB, and for all PCBs under each PSB.
- Message handling
- Code
- Conflict
- DBH
- OSAM I/O for message queues
- MFS
- MFS format library directory
- PMM
- Message format buffer pool space or control block I/O
- QMG
- Message queue management
- Scheduling
- Code
- Conflict
- BLR
- Load/read from ACBLIB
- MSC
- MPP region initialization
- SMN
- Virtual storage management
- Database access
- Code
- Conflict
- DBH
- OSAM I/O
- DLE
- DL/I functions
- VBH
- VSAM interface
- (Physical segment code)
- Program isolation
- External subsystems
- Code
- Subsystem call function
- AB0
- ABORT
- CT0
- Create thread
- D50
- Terminate identify or thread, signoff
- D80
- INIT
- I30
- Identify, command, echo, terminate
- I30
- Identify, terminate subsystem
- I50
- INIT
- I60
- Resolve-in-doubt
- PR0
- Subsystem-not-operational
- P10
- Commit prepare (Phase 1)
- P20
- Commit continue (Phase 2)
- SO0
- Signon
- SI0
- Identify
The following example show a sample of the report.
IMS MONITOR ****PROGRAM I/O**** TRACE START 1993 022 14:00:18 TRACE STOP 1993 022 14:02:20 PAGE 0088
.........IWAIT TIME..........
PSBNAME PCB NAME IWAITS TOTAL MEAN MAXIMUM DDN/FUNC MODULE
_______ ___ ____ ______ _____ ____ _______ ________ ______
PROGHR1A I/O PCB 122 2341116 19189 70795 HOTELDBA DBH
34 24177936 711115 3950160 **W F I
40 23652665 591316 2668917 **W F I
5 67613 13522 21214 SHMSG QMG
4 110363 27590 60486 QBLKS QMG
PCB TOTAL
___ _____ 131 2519092 19229
PSB TOTAL
___ _____ 305 6725063 20049
PROGDE1A TRMNALDA 20 624677 31233 68252 TRMNALDA VBH
1 275811 275811 275811 PI TRMNALDA....
PCB TOTAL
___ _____ 21 900488 42880
I/O PCB 16 488812 30550 79980 TRMNALDA VBH
1 16118 16118 16118 SHMSG QMG
PCB TOTAL
___ _____ 17 504930 29701
TABLEDBA 16 290471 18154 33254 TABLEDA DBH
PCB TOTAL
___ _____ 16 290471 18154
PSB TOTAL
___ _____ 54 1695889 31405
PROGHR2B HOTELDBB 8 698384 87298 184475 HOTELDBB DBH
4 5820650 1455162 1455278 PI HOSINDXB....
4 4481024 1120256 1209075 PI HOTELDBB....
2 260817 130408 232750 HOSINDOB VBH
7 106623 15231 16410 HOSINDXB VBH
1 15366 15366 15366 HOTELDBD DBH
PCB TOTAL
___ _____ 26 11382864 437802
PSB TOTAL
___ _____ 26 11382864 437802
PROGHR2A HOTELDBA 17 655801 38576 366108 HOSINDXA VBH
73 1836721 25160 82141 HOTELDBA DBH
2 54663 27331 41975 HOTELDBD DBH
1 9887 9887 9887 HOTELDBC DBH
2 851042 845635 845635 HOSINDOA VBH
PCB TOTAL
___ _____ 95 3408114 35874
I/O PCB 2O 575847 28792 74227 HOTELDBA DBH
21 370390 17637 43153 HOSINDXA VBH
IMS MONITOR ****PROGRAM I/O**** TRACE START 1993 022 14:00:18 TRACE STOP 1993 022 14:02:20 PAGE 0089
.........IWAIT TIME..........
PSBNAME PCB NAME IWAITS TOTAL MEAN MAXIMUM DDN/FUNC MODULE
_______ ___ ____ ______ _____ ____ _______ ________ ______
PROGHR2A I/O PCB 5 4654544 930908 2020043 **W F I
8 32796604 4099575 9328891 **W F I
PCB TOTAL
___ _____ 41 946237 23078
PSB TOTAL
___ _____ 136 4354351 32017
PROGPS2A LOGIMA 89 2046670 22996 73593 IMMSTR3A VBH
612 53886417 88049 185674 IMMSTR1A VBH
3 44906 14968 20788 IMINDEXA VBH
PCB TOTAL
___ _____ 704 55977993 79514
469 11742900 25038 170337 COMPOSDA DBH
329 8198418 24919 91422 CPINDEXA VBH
PCB TOTAL
___ _____ 798 19941318 24989
I/O PCB 3 47511 15837 20806 SHMSG QMG
PCB TOTAL
___ _____ 3 47511 15837
PSB TOTAL
___ _____ 1505 75966822 50476
PROGSC6C I/O PCB 52 2698602 51896 473763 INVENTRC VBH
4 70921 17730 34241 SHMSG QMG
3 50699 16899 24724 QBLKS QMG
PCB TOTAL
___ _____ 59 2820222 47800
55 2666884 48488 210752 INVENTRC VBH
50 797587 15951 41706 ININDEXC VBH
1 119253 119253 119253 PI INVENTRC...1
1 8634 8634 8634 INVENTRB VBH
2 83947 41973 53936 INVENTRA VBH
PCB TOTAL
___ _____ 109 3676305 33727
PSB TOTAL
___ _____ 168 6496527 38669
PROGHR2D I/O PCB 21 2285296 108823 199223 HOTELDBD DBH
28 762370 27227 111860 HOSINDXD VBH
1 11685 11685 11685 SHMSG QMG
PCB TOTAL
___ _____ 50 3059351 61187
HOTELDBD 96 6279107 65407 139032 HOTELDBD DBH
MONITOR ****PROGRAM I/O**** TRACE START 1993 022 14:00:18 TRACE STOP 1993 022 14:02:20 PAGE 0090
.........IWAIT TIME..........
PSBNAME PCB NAME IWAITS TOTAL MEAN MAXIMUM DDN/FUNC MODULE
_______ ___ ____ ______ _____ ____ _______ ________ ______
PROGHR2D HOTELDBD 31 2130585 68728 769130 HOSINDXD VBH
3 115999 38666 56394 HOTELDBA DBH
2 69833 34916 43470 HOTELDBC DBH
2 41430 20715 28020 HOSINDOD VBH
4 5515374 1378843 1458884 PI HOSINDXD....
4 3997017 999254 1026228 PI HOTELDBD....
PCB TOTAL
___ _____ 142 18149345 127812
PSB TOTAL
___ _____ 192 21208696 110461The I/O waits for the calls to the I/O PCB, are grouped as the first entries for a PSB. For DL/I calls, the data set for which the I/O took place is indicated under the DDN/FUNC heading, and the module code indicates what type of conflict caused the wait. For external subsystem calls, the function is indicated under the DDN/FUNC heading and the module code indicates the source of the call entry.
Names other than LGMSG and SHMSG can appear in the DDN/FUNC column for I/O PCBs. An example is a checkpoint call issued by an application program (using an I/O PCB) which causes a database buffer to be written.
If the program is designated as wait-for-input and has to wait for the input of the next message, the wait entry is marked **WFI under the DDN/FUNC heading and no entry appears in the MODULE column. The time spent waiting for the next input message is shown under wait time. **WFI entries are shown for information only and their values are not used to compute statistics.
Contention for the same physical segment in a database causes a wait on behalf of program isolation. This is shown in the DDN/FUNC column, on the PCB line, by the entry PIdmb, where dmb is the DMB of the physical data set. The MODULE column identifies the segment type using the physical segment code assigned by DBD generation.
When an application is accessing a database using VSAM as the access method, DL/I calls do not generally result in an I/O wait. A MODULE column entry of VBH indicates that interface to VSAM occurred and there was an I/O wait.
A seemingly unrelated entry can occur under the DDN/FUNC column for a database PCB. An example is a retrieval call to a database (DB-A) that causes a buffer to be purged in order to make room for that retrieved data. If the buffer contents included data belonging to another database (DB-B), the I/O entry in the report shows the DD name for DB-B as being in conflict for PCB access to DB-A.