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Performance Management

These changes affect the performance management of z/VM:

  • Monitor Enhancements
  • Command Syntax and Output Changes
  • Effects on Accounting Data
  • VM Performance Products

Monitor Enhancements

There were several changes and areas of enhancements affecting the monitor data for z/VM 5.2.0 involving system configuration information and improvements in data collection. As a result of these changes, there are two records that are no longer generated, seven new monitor records, and several changed records. The detailed monitor record layouts are found on our control blocks page.

In z/VM 5.2.0, the Vector Facility is no longer available so support for the facility has been removed. As a result, the Domain 5 Record 4 (Vary on Vector Facility) and the Domain 5 Record 5 (Vary off Vector Facility) monitor records are no longer generated. In addition, there are fields which were used for monitoring the Vector Facility which are no longer provided in the following records: Domain 0 Record 2 (Processor Data (Per Processor)), Domain 1 Record 4 (System Configuration Data), Domain 1 Record 5 (Processor Configuration), Domain 4 Record 2 (User Logoff Data), Domain 4 Record 3 (User Activity Data), and Domain 4 Record 9 (User Interaction at Transaction End).

Preferred guest support (V=R) was discontinued in z/VM 5.1.0 and all related monitor fields were changed to display zeros. With z/VM 5.2.0, fields used to capture data for this support have been removed from the Domain 0 Record 3 (Real Storage Data (Global)), Domain 1 Record 7 (Memory Configuration), Domain 3 Record 1 (Real Storage Management(Global)), and the Domain 3 Record 2 (Real Storage Activity (Per Processor)) records. Also, the VMDSTYPE value of X'80', representing V=R, is no longer valid. This value was reported in the Domain 1 Record 15 (Logged on User), Domain 4 Record 1 (User Logon), Domain 4 Record 2 (User Logoff Data), Domain 4 Record 3 (User Activity Data), and the Domain 4 Record 9 (User Activity Data at Transaction End) records.

A new record, Domain 3 Record 18 (SCSI Storage Pool Sample), has been added to allow monitoring of storage utilization in a SCSI container storage subpool. In z/VM 5.1.0, support was added to provide native SCSI disk support. This record is a follow-on to the monitor support added in the previous release and provides data for a SCSI storage subpool including the name, size, number of malloc() and free() calls, bytes currently allocated, as well as additional data which can be used to keep track of storage usage for SCSI devices.

Support was added to z/VM 5.2.0 for a Guest LAN sniffer debugging facility. It provides a LAN sniffing infrastructure that will support Linux network debugging tools as well as VM and Linux users who are familiar with the z/VM operating system. The Domain 6 Record 21 (Virtual Switch Activity) record has been updated to include two new fields which indicate the count of the current active trace ids and the count of the current users in Linux sniffer mode.

Two new monitor records, Domain 5 Record 9 (Crypto Performance Counters) and Domain 5 Record 10 (Crypto Performance Measurement Data), have been added to allow monitoring of cryptographic adapter cards. These records include counters and timers for transactions on the cryptographic adapter cards and measurement data for each specific cryptographic adapter card in the system configuration.

Starting with the z890 and z990 processors (with appropriate MCL) and z/VM 5.2.0, a program running in a virtual machine has the option of using the Queued Direct I/O (QDIO) Enhanced Buffer State Management (QEBSM) facility to manage QDIO buffers for real dedicated QDIO-capable devices (OSA Express, FCP, and HiperSockets). The following monitor records have been extended to provide data for the new QEBSM support: Domain 1 Record 19 (indicates configuration of a QDIO device), Domain 6 Record 25 (indicates that a QDIO device has been activated), Domain 6 Record 26 (indicates activity on a QDIO device), and Domain 6 Record 27 (indicates deactivation of a QDIO device).

In z/VM 5.2.0, users can now specify preferred and non-preferred channel paths for emulated SCSI devices on the IBM 1750 (DS6000) storage controller. This information has been added to the Domain 1 Record 6 (Device Configuration Data), Domain 6 Record 1 (Vary on Device), and the Domain 6 Record 3 (Device Activity) records.

The largest change to the monitor records for z/VM 5.2.0 has been in the area of storage management due to the improved support for large real storage. This allows z/VM 5.2.0 to use storage locations above the 2 GB address line for operations that previously required moving pages below the 2 GB line. All monitor records reporting data on storage have been modified. There are several fields which are no longer available and many new fields. There are also some fields which have a somewhat different meaning: Prior to z/VM 5.2.0, these fields reported data on the total amount of storage. In z/VM 5.2.0, these fields now represent data for storage below 2 GB only. In most cases, new fields have been added to report storage data above 2 GB. To assist in understanding the fields involved, the control blocks page lists each monitor record changed along with a list of the fields within the record that have been removed, added, or have a new meaning. The list of changed records include:

Monitor Record Record Name
Domain 0 Record 3 Real Storage Data (Global)
Domain 0 Record 4 Real Storage Data (Per Processor)
Domain 1 Record 7 Memory Configuration Data
Domain 3 Record 1 Real Storage Management (Global)
Domain 3 Record 2 Real Storage Management (Per Processor)
Domain 3 Record 3 Shared Storage Management
Domain 3 Record 14 Address Space Information Record
Domain 3 Record 16 NSS/DCSS/SSP Removed from Storage
Domain 4 Record 2 User Logoff Data
Domain 4 Record 3 User Activity Data
Domain 4 Record 9 User Activity Data at Transaction End

In addition to the changes in the existing storage management areas within monitor, there are four new storage management records that contain data for the new storage concept in z/VM 5.2.0 known as the System Execution Space. Two new high-level System Execution Space monitor records have been added to the System Domain: Domain 0 Record 21 (System Execution Space (Global)) and Domain 0 Record 22 (System Execution Space (Per Processor)). Two System Execution Space monitor records that contain more detailed information have been added to the Storage Domain: Domain 3 Record 19 (System Execution Space (Global)) and Domain 3 Record 20 (System Execution Space (Per Processor)).

Command Syntax and Output Changes

The extensive changes to CP storage management necessitated some changes to the syntax and/or output of a number of CP commands. Performance management tools that use these commands should be reviewed to see if any updates are required.

Changed CP Commands

Command Syntax Output
DISPLAY host address X X
DUMP host address X X
STORE host address X X

There are three new commands: QUERY SXSPAGES, QUERY SXSSTORAGE, and LOCATE SXSTE. These are in support of the new System Execution Space component.

Effects on Accounting Data

The values reported in the virtual machine resource usage accounting record will be affected for guest virtual machines that use the QEBSM assist for QDIO data transfers. Relative to not using QEBSM, virtual CPU time reported for that guest will tend to be somewhat higher, while CP CPU time can be much lower.

Performance Toolkit for VM

Performance Toolkit for VM has been enhanced to include the following additional data. These are all new reports except for PAGELOG, which has been updated:

  • Storage management ..
    • PAGELOG - Total Paging Activity (by time). Two data columns (Nonpageable Pages and Resident Shared Pages) were moved to the new STORLOG report, one column (Mean Available List) was moved to the new AVAILLOG report, and two columns (Page Table Mgmt Reads and Writes) were added.
    • STORLOG - Storage Utilization Log (by time)
    • AVAILLOG - Available List Management (by time)

  • New System Execution Space storage management component ..
    • SXSAVAIL - SXS Queues Management (by time)
    • SXSPAGE - SXS Page Management (by time)
    • SXSDEFER - SXS Deferred Tasks Management (by time)
    • SXSUTIL - SXS Utilization (by time)

    • QEBSM - QEBSM device activity (by device)
    • QEBSMLOG - QEBSM device activity log (by time)
    • UQDIO - User QDIO Activity Information (by user)
    • UQDIOLOG - User QDIO Log (by time)

  • Other ..
    • DEMNDLOG - Demand Scan Details (by time)

Currently, Performance Toolkit for VM does not accurately calculate I/O response time when CP is using parallel access volumes (PAV) for user minidisks. See Performance Toolkit for VM and PAV for details. The reported I/O service times are correct. Bear in mind, however, that they are for each listed device number and not for the DASD volume as a whole.

For general information about Performance Toolkit for VM and considerations for migrating from VMPRF and RTM, refer to the Performance Toolkit for VM page.

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