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Programming Interface Information:
The Monitor Records are intended Programming Interfaces that allow the customer to write programs to obtain services of z/VM. |
MRSEKSEK
PrologControl Block Contents
Cross Reference
MRSEKSEK Prolog
DSECT NAME - SEKSEK
FUNCTION - Map a Monitor record.
LOCATED By -
Through the Monitor Control Area
REFERENCED CONTROL BLOCKS -
MRRECHDR Monitor Record Header
NAME - MRSEKSEK
DESCRIPTIVE NAME - Monitor Event Record
Domain 7 - Seek Domain
Record 1 - Seek Data
DESCRIPTION - Record of access arm movement ("Seek I/O") on a DASD
device or of a set paging parameter to a cache device.
Generated each time an I/O channel program containing
seek commands(s) is executed.
This record contains seek data that may enable a
user, such as an operating system developer, to tune
DASD seek scheduling algorithms. This record is NOT
intended for DASD load balancing. However, it can be
used to tune a cached minidisk to minimize the number
of tracks that must be cached.
NOTES:
-- Because of the frequency of seek I/O operations, an extremely
large number of this record will be generated. For this
reason, seek-domain monitoring should be limited to specific
devices or a specific set of devices.
-- The order in which the records are generated may not be the
order in which the commands are executed by the device.
-- The seek may not be executed by a device when there is a
permanent device error or when branching is done in the channel
program which bypasses segments.
MRSEKSEK Control Block Contents
Offsets
Dec Hex Type Len Name (Dim) Description
0 0 Structure 60 SEKSEK Start of monitor record
0 0 Character 0 SEKSEK_MRHDR Record header. See MRRECHDR for
details.
0 0 Character 20 MRHDR
0 0 Unsigned 2 MRHDRLEN record length in bytes
2 2 Unsigned 2 MRHDRZER field of zeros
4 4 Unsigned 1 MRHDRDM domain identifier
5 5 Unsigned 1 *
6 6 Unsigned 2 MRHDRRC record identifier
8 8 Character 8 MRHDRTOD Time at which this record was
built. In time-of-day (TOD) clock
format. See IBM System 370 XA
Principle of Operation for
explanation of format.
16 10 Character 4 *
20 14 Character 0 MRHDR_END End of header
20 14 Unsigned 4 SEKSEK_RDEVSID Host subchannel I.D. number
defined at initialization
24 18 Unsigned 2 SEKSEK_CALCURCY Last seek cylinder for previous
DASD channel program executed.
RDEVCYL
26 1A Unsigned 2 SEKSEK_CALSKCYL First cylinder requested in seek
command(s) in this real channel
program. IORCYL
28 1C Unsigned 2 SEKSEK_CALSKHD First head number requested in
seek command(s) in this real
channel program. IORHEAD
30 1E Bitstring 1 SEKSEK_CALFLAGS Flag byte
1... .... SEKSEK_IORDWRIT ON=This is a WRITE channel
program. OFF=This is a READ
channel program.
.1.. .... *
..1. .... *
...1 .... *
.... 1... *
.... .1.. *
.... ..1. *
.... ...1 *
31 1F Bitstring 1 * Reserved for IBM use
32 20 Character 8 SEKSEK_VMDUSER Userid of requestor of seek
command(s) in this real channel
program. If 'SYSTEM', CP is the
requestor.
40 28 Unsigned 4 SEKSEK_IORPOSCT Number of DASD access arm
position changes within this real
channel program.
44 2C Unsigned 4 SEKSEK_IORPOSSM Amount of access arm movements
(displacements). Cumulative total
of absolute differences, in
cylinders, between successive seek
operation within this real channel
program
48 30 Unsigned 2 SEKSEK_CALECYL Final cylinder number (position
after this real channel program
completes). IORECYL
50 32 Unsigned 2 SEKSEK_VDEVDEV Virtual device number of the
target device. Not applicable if
CP is the requestor (i.e.,
SEKSEK_VMDUSER = 'SYSTEM').
52 34 Character 8 SEKSEK_CALUSER Userid of the owner of the
target device. Not applicable if
CP is the requestor (i.e.,
SEKSEK_VMDUSER = 'SYSTEM').
60 3C Character 0 SEKSEK_END
MRSEKSEK Cross Reference
Hex Hex
Name Offset Length Value
MRHDR 0 20
MRHDR_END 14 0
MRHDRDM 4 1
MRHDRLEN 0 2
MRHDRRC 6 2
MRHDRTOD 8 8
MRHDRZER 2 2
SEKSEK 0 60
SEKSEK_CALCURCY 18 2
SEKSEK_CALECYL 30 2
SEKSEK_CALFLAGS 1E 1
SEKSEK_CALSKCYL 1A 2
SEKSEK_CALSKHD 1C 2
SEKSEK_CALUSER 34 8
SEKSEK_END 3C 0
SEKSEK_IORDWRIT 1E 80
SEKSEK_IORPOSCT 28 4
SEKSEK_IORPOSSM 2C 4
SEKSEK_MRHDR 0 0
SEKSEK_RDEVSID 14 4
SEKSEK_VDEVDEV 32 2
SEKSEK_VMDUSER 20 8
This information is
based on z/VM V4R4.0.
Last updated on 22 Jul 2003 at 15:04:23.
Copyright IBM Corporation, 1990, 2003