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 64 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 Unsigned 2 SEKSEK_RDEVDEV Device number 62 3E Unsigned 2 * Reserved and available for IBM use. 64 40 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 64 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 40 0 SEKSEK_IORDWRIT 1E 80 SEKSEK_IORPOSCT 28 4 SEKSEK_IORPOSSM 2C 4 SEKSEK_MRHDR 0 0 SEKSEK_RDEVDEV 3C 2 SEKSEK_RDEVSID 14 4 SEKSEK_VDEVDEV 32 2 SEKSEK_VMDUSER 20 8
This information is based on z/VM V5R3.0.
Last updated on 12 Jun 2007 at 12:35:23.
Copyright IBM Corporation, 1990, 2007