MRSEKSEK

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