|
 |
|
 |
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
- Selected APARs that affect VM performance
- Base APARs are listed
- Pre-reqs, Post-reqs (PEs), Co-reqs, and If-reqs may
not be listed
- Research APARs required for your system!
- Most Performance APARs tested in production
- May not be bug free
- PEs may or may not apply in your environment
- APARs may not be on an RSU
APARs may be OPEN, in Fix Test, or Correctively
Available
z/VM 6.2.0 APARs
- VM65060
- Improves the performance associated with diagnose x'10' processing
as used by
LINUX CPUPLUGD memory unplug function. This removes the need to put the
virtual machine in console function mode for serialization.
This APAR also applies to z/VM 6.1.0 and z/VM 5.4.0, and is on RSU 1201.
- VM65011
- Corrects VM64943 which in combination with this avoids abends and other
problems when the *MONITOR system service is used on a server where
Global Performance Data control has been disabled. This APAR also
applies to z/VM 6.1.0 and z/VM 5.4.0.
z/VM 6.1.0 APARs
- VM64927
- CP use of Diagnose x'44' can lead to high LPAR overhead.
This APAR will decrease the amount of LPAR overhead created
by spin lock contention and associated diagnose x'44'
instructions issued by CP and diagnose x'9C' instructions
issued by the guest. Also introduced additonal monitor fields
instrumenting spin locks in CP.
This is on RSU 1101.
- VM64905
- Checkpoint processing is slow on SCSI Disk.
The checkpoint phase of shutdown processing takes significantly
longer if the checkpoint volume resides on SCSI DASD using
N-Port Virtualization.
During the checkpoint phase of shutdown processing, the
HCPCKSEP entry point is called each time a page must be
written to SCSI DASD. Each time HCPCKSEP is called it
initializes QDIO queues to the checkpoint volume and then
resets the queues. The performance overhead of this is
negligible unless NPIV is being used. Initialization takes
much longer with NPIV activated because of additional
required delays.
Also applies to z/VM 5.4.0. For 6.1.0, it is on RSU 1102.
- VM64887
- Problem description is erratic system performance or brief system
hang.
When there is a lot of contention for CPU time and the PLDVs
overflow, special processing is needed to ensure that all ready
users are eventually dispatched. An error was found in the PLDV
reshuffle code that delayed dispatching them. This can result
in erratic system performance or brief system hangs.
This APAR also applies to z/VM 5.4.0. It is on RSU 1102 for both
releases.
- VM64850
- Controlled failover on VSwitches causes performance problems. Also
applies to z/VM 5.4.0
- VM64808
- PGMBK Steal can incorrectly skip PGMBKs, resulting in sub-optimal
performance in memory constrained environments.
This fixes PE VM64225. Also applies
to z/VM 5.4.0 and z/VM 5.3.0. On RSU 1002 for all three releases.
- VM64798
- Required updates to z/VM are made to support the z196 processor.
This includes compatibility with new facilities and storage
management performance improvements using non-quiescing and
conditional SSKE. This APAR alone is not sufficient for z196 support,
please see service bucket for full details. This APAR also applies
to z/VM 5.4.0. It is in RSU 1003 for both releases.
- VM64774
- SET/QUERY REORDER command. See
this article
for more information. Also applies to z/VM 5.4.0. In RSU 1003 for both
releases.
- VM64756
- Long CPEBK chains for user SYSTEMMP are not processed in timely fashion. Can
lead to VAP002 abends or other problems due to the delays. Also applies to
z/VM 5.4.0 and z/VM 5.3.0.
- VM64728
- Corrects monitor records that include share setting by processor type.
Also applies to z/VM 5.4.0.
- VM64715
- Page Release serialization impacts performance.
Release processing was changed to do as much processing while
holding PTIL shared (PTIL-s) as possible, only switching to
holding PTIL exclusive (PTIL-x) when necessary. Changed modules
in release processing are HCPHPC, HCPHPH, and HCPHPK. Some
callers of release entry points also required subsequent minor
changes. Impact more significant for environments with DB/2 for
z/VM and VSE. Also applies to z/VM 5.4.0.
- VM64527
- Corrects imbalance in managing control blocks associated with
dedicate FCP and QDIO devices that left uncorrected can result in
MCW002 Abends. Also applies to z/VM 5.4.0 and z/VM 5.3.0
z/VM 5.4.0 APARs
- VM64633
- When storage above 2G is constrained, CP erroneously uses only
one shortterm subpooled block within a 4K page of storage
that is backed below 2G. This causes an inefficient usage of
available storage.
- VM64603
- CCW Translation changed to improve performance for CMS format.
See also VM64602. Also applies to z/VM 5.3.0 and z/VM 5.2.0.
- VM64602
- Improves performance of CMS Format command.
Also applies to z/VM 5.3.0
- VM64533
- Improves NFS performance when performing OPENVM PUTBFS operations.
Also applies to z/VM 5.2.0 and z/VM 5.3.0.
- VM64513
- Improves SFS performance when erasing large files. Without APAR, ERASE
can take hours to erase large SFS files (>5GB).
Also applies to z/VM 5.3.0.
- VM64510
- Improves MDC utilzation from problem introduced with VM64082.
Also applies to z/VM 5.3.0.
- VM64495
- Introduces DUMPLD2 utility which is replacement for DUMPLOAD and allows
a dump file to be segmented into multiple files when space is limited and the
dump needs to span multiple disks.
Also applies to z/VM 5.3.0
- VM64482
- This introduces slight CMS performance hit in some scenarios. It corrects
a functional problem where control is not returned to program after an
FSWRITE call. The fix removes the fastpath processing for WRBUF (FSWRITE).
Also applies to z/VM 5.2.0 and z/VM 5.3.0.
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
- OA40894
-
Connections traversing HiperSockets experience performance
degradation, the results of which range from slow data tranfers
to connection termination. The problem may not occur
immediately after an IPL, but instead make take several days to
surface.
This affects only connections which use zIIP-assisted
IQDIOMULTIWRITE, configured on the GLOBALCONFIG statement of the
TCPIP profile.
Return to the Performance Tips Page
|
|
|