| |
Hex Dec Type/Val Lng Label (dup) Comments
---- ---- --------- ---- -------------- --------
0000 0 Structure PHDBK Paging Information Header Block
0000 0 Character 8 PHDEYE Eyecatcher HCPHXPBK or HCPEXPBK
0008 8 Bitstring 1 PHDTYPEF Flag byte for access type. Used
directly by Perfkit. Do not
change offset. Task
serialization.
1... .... PHDHXPBK X'80' Indicates area being mapped
is within an HXPBK; when bit is
0, area mapped is within an EXPBK
.1.. .... PHDECKD X'40' ECKD device
..1. .... PHDSCSI X'20' Native SCSI device (EXPBK
only)
...1 .... PHDFBA X'10' FBA device
0009 9 Bitstring 1 * (3) Reserved for IBM use
000C 12 Signed 4 * Reserved for IBM use
Monitor counts of read and write operations for this device
0010 16 Dbl-Word 8 * (0) Alignment
0010 16 Signed 4 PHDCTPRD Total count of page reads. Used
directly by Perfkit. Do not
change offset. Compare & Swap to
update.
0014 20 Signed 4 PHDCTPWR Total count of page writes Used
directly by Perfkit. Do not
change offset. Compare & Swap to
update.
0018 24 Signed 4 PHDCTSRD Total count of spooling reads
Used directly by Perfkit. Do not
change offset. Compare & Swap to
update.
001C 28 Signed 4 PHDCTSWR Total count of spooling writes
Used directly by Perfkit. Do not
change offset. Compare & Swap to
update.
0020 32 Signed 4 PHDSSCHR Total count of SSCHs (or RSCHs
when EXPBK) for read. Used
directly by Perfkit. Do not
change offset. Task
serialization.
0024 36 Signed 4 PHDSSCHW Total count of SSCHs (or RSCHs
when EXPBK) for write. Used
directly by Perfkit. Do not
change offset. Task
serialization.
0028 40 Signed 4 PHDLOCRR Total count of Locate Record
operations for read (includes the
initial search even when the
information is provided by a
Prefix CCW). Used directly by
Perfkit. Do not change offset.
Task serialization.
002C 44 Signed 4 PHDLOCRW Total count of Locate Record
operations for write (includes
the initial search even when the
information is provided by a
Prefix CCW). Used directly by
Perfkit. Do not change offset.
Task serialization.
Device service time and MLOAD fields
0030 48 Dbl-Word 8 * (0) Alignment
0030 48 Signed 4 PHDDEVST Device service time. In EXPBK,
serialized by EXPLCKFG. In PHDBK,
serialized by HXPC1LCK. Used
directly by Perfkit. Do not
change offset. Compare & Swap to
update.
0034 52 Signed 4 PHDMLOAD MLOAD. Serialized by HCPPGDML.
Used directly by Perfkit. Do not
change offset.
Slot allocation
0038 56 Dbl-Word 8 * (0) Alignment
0038 56 Signed 4 PHDCONT (20) Array of 20 fullword slot
allocation counters. The count at
index (i) is incremented each
time a block with (i) contiguous
slots is allocated. The last
count in the array is also
incremented when a block w/
>20 slots is allocated. Used
directly by Perfkit. Do not
change offset. Serialization is
HCPPGDPL for a paging volume, and
HCPPGDSL for a spool volume.
Accuracy of these counters depend
on volume usage not being mixed
page and spool as per
recommendations.
0088 136 Address 4 PHDRDCBK Pointer to RDCBK which contains
device/control unit information
Task serialization.
008C 140 Signed 4 * Reserved for IBM use.
Reserved area
If there is a need in the service stream to add additional
fields to the PHDBK, the following reserved area should be
used to avoid changing offsets of EXPBK fields and
recompiles to all of the legacy paging code.
Lengthening the PHDBK (up to 256 bytes) does not have the
same consideration for the HXPBK because the PHDBK is in its
own HXPBK cache line.
0090 144 Dbl-Word 8 * (4) Reserved for IBM use.
000000B0 PHDBSIZE *-PHDBK Size of this DSECT in
Bytes
00000016 PHDSIZE (((*-PHDBK)+7)/8) Size in
double-words
| |