Performance Related APARs

The following is a list of performance related APARs. It does not replace the need for normal service process. See The z/VM Service Page for additional service information.

Disclaimers

1. Selected APARs that affect VM performance
2. Base APARs are listed
   • Pre-reqs, Post-reqs (PEs), Co-reqs, and If-reqs may not be listed
   • Research APARs required for your system!
3. Most Performance APARs tested in production
   • May not be bug free
   • PEs may or may not apply in your environment
4. APARs may not be on an RSU

APARs may be OPEN, in Fix Test, or Correctively Available

Linux Guest

OSA-Express QDIO Performance Enhancements Requirements

This document lists enhancements made to software and microcode for those customers interested in running Linux guests that use OSA-Express QDIO to communicate.

Queued I/O Assist Requirements

This document lists the requirements for all components involved in this enhancement made in z/VM 4.4.0.

QDIO Enhanced Buffer State Management Requirements

This document lists requirements for all components involved in this enhancement made in z/VM 5.2.0.

z/OS 1.8

OA20553

Slow network performance when running z/OS as guest of z/VM with dedicated OSA adapter.

TCP/IP and Friends (Level 520)

PK11392

Improves performance when using VIPA with multiple interfaces. Also applies to FL 510.

z/VM 5.3.0 APARs

VM64400

Minidisk cache bypassed on DS6800 1750 devices. Also applies to z/VM 5.2.0.

VM64349

Turnover rate balancing algorithm enhancements; improves balance of pages below and above 2GB on large (100 GB or more) systems. Also applies to z/VM 5.2.0

VM64323

No LPAR monitor records after EDM upgrade (PE from VM63853). Also applies to z/VM 5.2.0

VM64304

CP determines incorrect CPU type of alternate processors. Potential results in all Linux work being dispatched on master processor.

VM64292

Monitor I/O receives command rejects for PAV Alias Devices. Also applies to z/VM 5.2.0.

VM64297

Slow ping response times over QDIO with more than one virtual processor. Also applies to z/VM 5.2.0.

VM64269

Excessive paging activity during demand scan

VM64031

ABEND HTT001 or HTT002 page translation in CP Monitor. APAR changes monitor appldata buffer length interface. Additonal Information. Also applies to z/VM 5.2.0.

VM64248

CP sends no I/O to HyperPAV aliases attached to SYSTEM

VM63884

Page packs not utilized correctly; fixes calculations for MLOAD computation. Also applies to z/VM 5.2.0.

z/VM 5.2.0 APARs

VM64333

MDC and other frame allocation and turnover rate fixes

VM64213

Memory leak in SYSPERM or GUESTPERM free storage

VM64073

Speeds up VM simulation of Coupling Facility related instruction

VM64042

Storage leak in aligned free storage types

VM64031

ABEND HTT001 or HTT002 page translation in CP Monitor. APAR changes monitor appldata buffer length interface. Additonal Information.

VM64027

System hang due to monitor trying to acquire contiguous pages for LPAR

VM64009

Corrects Monitor memory leak when running on processors without crypto devices.

VM63961

SPXTAPE LOAD filling up spool with unaccounted pages.

VM63958

Slow IPL of z/OS guests

VM63955

SYSTEM HANG ON SRMSLOCK SCHEDULER LOCK AND RSAAVLLK

VM63935

Avoids unnecessary clearing of memory in CMS

VM63916

Corrects ASCCTPGS field updating and bad values in monitor regarding paging counts.

VM63893

Improves minidisk cache performance.

VM63892

Corrects locked page counts used by Q FRAMES and CP monitor.

VM63877

Corrects an error in the value reported for the LockedRS field in the Q FRAMES output.

VM63845

Corrects high demand scan CPU time that occurs for certain paging workloads

VM63841

Improves performance of emulated FBA on SCSI. This also applies to z/VM 5.1.0