IP/UP USAGE During initialization cn the VM/370 monitor# V8/370 stores the logical
address of the processor and the logical address of the attached
processor into the V8/370 monitor spool file header record. When USER class of data, the V5/370 monitor now records the logical address of the last processor to service the user. The VM/370 monitor also records this information in the monitor record for the SCHEDULE class at queue drop time. SELECTIVE SEEKS An installaticn that uses the
device for which seek related DASD devices for which no seek INCLUDE and EXLCUDE, have been
reflect this enhancement. VM/370 monitor can now specify the DASD information is to te coiiected, or information is desired. Two new options,
added to the CP BOWITOR SEEKS command to MONITOR-TO-DISK SUPPORT FOR REAL TIME The system programmer can now request that the VB/370 monitor close the monitor spool file after a specified number of .onitor samples bas been made; be does this via the LIMIT operand of the SISSON macro instruction
which has been updated. Similarly changed is the tI!IT option of the CP MONITOR command. In addition, the minimum sample interval for the USER, and DASTAP monitor classes is reduced fr08 30 seconds to
5 seconds. This new support enables more frequent and regular real time data reduction of the monitor spool file. SRL AND PROGRAM LOGIC PUBLICATIONS The following publications contain information on the VB/370 measurement
facility(monitor): GC20-1801 Planning and System Generation Guide GC20-1806 Operator's Guide GC20-1807 System Programmer's Guide GC20-1808 System Messages SY20-0884 Data Areas and Control Block Logic SY20-0886 System Logic and Problem Determination Guide, Vol. 1
Section 1. Summary of Changes to the VB/370 System 1-13
Shared Segment Modifications
The following mcdifications have been made to shared segments: ELIMINATION OF AUTO!ATIC UNSBARE A shared segment is defined as reentrant, read-only cede. Prior to
Release 6, a user who modified a shared segment was unshared from the
shared copy of that segment and given a private cOFY of the segment with
his change intact. 'M/370 gave other users of that segment access to a
fresh copy of that segaent.- Under Release 6, if a user modifies a shared segment, except by means of the CP ADSTOP, TRICE, or STORE commands, VM/370 places the user in console function mode and returns the .odified page(s) to free storage.
The next reference to that page causes a fresh copy to be paged in from backing storage.
a user of a shared segment causes a page of that segment to be
by issuing an ADSTOP, TRICE, or STORE command, the user is from that shared seg.ent and given his own copy of that
Other users of the segment continue to operate with an
copy cf that segment. When altered
unshared segment. unchanged UNPROTECTED SHARED SEGMENTS Installations that use shared segments have the option, under Release 6, of running with cut protection against changes to these segments. If a
shared segment is specified to be a change made by the user
of that shared segment is seen by all other users of that shared
segment.
This option, when selected, eliminates the need for V!/370 to scan
for changed shared pages in both IP and UP aodes. In IP mode, a gain in pageable storage is acheived because VM/370 need not switch page table
pointers and need not maintain duplicate copies of shared segments. The NAftESYS system generation macro instruction has been modified to support
this option. Note that shared segment protection is the default
specification. Installations that choose to employ the unprotected
shared segments option should do so with caution and discretion. 1-14 IBM VM/370 Release 6 Guide
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