A fix is available
APAR status
Closed as new function.
Error description
This APAR exploits the warning-track-interruption facility, enabling CP to act when a logical CPU will be undispatched. Warning-track interruptions tell CP when PR/SM is going to undispatch a logical CPU. In response, CP can release any shared resources and undispatch the guest so it can be run elsewhere.
Local fix
N/A
Problem summary
**************************************************************** * USERS AFFECTED: Multi-LPAR configurations that are * * vertically polarized, contain CPUs that have * * low or medium entitlement and experience * * guest suspension, will benefit the most from * * the support delivered in VM66678. * **************************************************************** * PROBLEM DESCRIPTION: * **************************************************************** * RECOMMENDATION: APPLY PTF * **************************************************************** APAR VM66678 enables exploitation of the warning-track-interruption facility, implemented by the IBM zEC12. The facility introduces interruptions that warn a control program (CP) when PR/SM is going to undispatch a logical CPU (LCPU) from its physical CPU. When enabled in z/VM CP, these warnings allow CP to clean up any guest work and undispatch the guest running on the LCPU such that it can be run elsewhere. Without exploitation, any work running on an LCPU being undispatched ceases to make progress until PR/SM redispatches the LCPU. The symptoms of this situation include long transaction response times for guests, excessive use of coping mechanisms by guests (diag x'44', diag x'9C'), excessive use of coping mechanisms by CP (diag x'9C'), and generally poor performance. Multi-LPAR configurations that are vertically polarized, contain CPUs that have low or medium entitlement and experience guest suspension will benefit the most from exploitation, though there may be some benefit for other configurations. With this support applied, CP's exploitation of warning track will be enabled by default. CP will use the warning-track interruptions to release any shared software resources, undispatch the guest and allow the guest to be run elsewhere. In the meantime, other guests will have access to the shared resource that would have been held up otherwise. Exploitation has shown improvement of the above symptoms in the described environment. The support may be enabled/disabled via the new SRM WARNINGTRACK statement and the new SET SRM WARNINGTRACK command. The settings can be queried through QUERY SRM WARNINGTRACK/ALL. New and changed trace codes are added by this APAR, along with new monitor records. Changes to Perfkit are delivered in APAR VM66709. The Perfkit support uses new monitor data to calculate the suspend time for guests, taking into account the known time spent undispatched due to PR/SM's scheduling of logical CPUs.
Problem conclusion
Temporary fix
FOR RELEASE VM/ESA CP/ESA R730 : PREREQ: VM66423 VM66679 VM66434 VM66675 VM66689 VM66673 CO-REQ: NONE IF-REQ: NONE
Comments
This APAR delivers new function support to exploit the warning-track-interruption facility in CP. This support improves guest response time and overall performance of workloads that are run on vertical low or vertical-medium processors. The support for this facility includes updates to external interruption handling, dispatching, along with new externals. The externals include a new WARNINGTRACK operand on the SRM configuration file statement, and on the SET SRM and QUERY SRM commands, new warning track output for QUERY SRM ALL or QUERY SRM WARNINGTRACK, new and changed trace codes, new monitor records, and an update to the way Perfkit calculates suspend time. The following changes have been made to the z/VM publications: ***START PUBLICATION CHANGE************************************* * PUBLICATION TITLE: z/VM: CP Planning and Administration * * RELEASE: z/VM 7.3 * * ORDER NUMBER: SC24-6271-73 * *--------------------------------------------------------------* SECTION: Summary of Changes for z/VM: CP Planning and Administration UPDATE: describes the new WARNINGTRACK operand on the SRM configuration file statement. CHAPTER 6: The System Configuration File SECTION: SRM Statement UPDATE: adds the WARNINGTRACK operand and description to the SRM configuration statement and a new usage note to further explain the new operand. *--------------------------------------------------------------* * PUBLICATION TITLE: z/VM CP Commands and Utilities Reference * * RELEASE: z/VM 7.3 * * ORDER NUMBER: SC24-6268-73 * *--------------------------------------------------------------* SECTION: Summary of Changes for z/VM CP Commands and Utilities Reference UPDATE: describes the new WARNINGTRACK operand on the QUERY and SET SRM commands. CHAPTER 2: CP Commands SECTION: QUERY SRM UPDATE: adds the WARNINGTRACK operand and description to the QUERY SRM command and shows the new response. The QUERY SRM ALL response is also updated to add the new warning-track information to the response. CHAPTER 2: CP Commands SECTION: SET SRM UPDATE: add the WARNINGTRACK operand and description to the SET SRM command and shows the new response. New message variation to HCP1050E is added to the message list for unsuccessful enablement of warning track. *--------------------------------------------------------------* * PUBLICATION TITLE: z/VM: CP Messages and Codes * * RELEASE: z/VM 7.3 * * ORDER NUMBER: GC24-6270-73 * *--------------------------------------------------------------* SECTION: Summary of Changes for z/VM: CP Messages and Codes UPDATE: lists the new messages added by the warning-track support. CHAPTER 3: System Messages SECTION: CP Messages UPDATE: lists a new HCP1050E variation added for the SET SRM WARNINGTRACK ON command and a new HCP1051E variation added for the SRM WARNINGTRACK configuration file statement. *--------------------------------------------------------------* * PUBLICATION TITLE: z/VM: Diagnosis Guide * * RELEASE: z/VM 7.3 * * ORDER NUMBER: GC24-6280-73 * *--------------------------------------------------------------* SECTION: Summary of Changes for z/VM: Diagnosis Guide UPDATE: describes the updates to trace codes introduced by the warning-track support. CHAPTER: Appendix C SECTION: Trace Table Codes TABLE 15: Trace codes for 32-byte entries UPDATE: shows the updated content of trace entry 3600. CHAPTER: Appendix C SECTION: Trace Table Codes TABLE 15: Trace codes for 64-byte entries (Format 2) UPDATE: shows the new 3601 and 3602 trace entries. *--------------------------------------------------------------* * PUBLICATION TITLE: z/VM: Performance * * RELEASE: z/VM 7.3 * * ORDER NUMBER: SC24-6301-73 * *--------------------------------------------------------------* SECTION: Summary of Changes for z/VM: Performance UPDATE: lists the monitor record changes delivered by this APAR. *--------------------------------------------------------------* * PUBLICATION TITLE: z/VM: Migration Guide * * RELEASE: z/VM 7.3 * * ORDER NUMBER: GC24-6294-73 * *--------------------------------------------------------------* SECTION: Summary of Changes for z/VM: Migration Guide UPDATE: lists changes made by the warning-track support. CHAPTER 1: Introduction SECTION: New Function Variables UPDATE: shows the new function variable for warning-track support. CHAPTER 2: System Changes SECTION: Support and Exploitation of Hardware and Architectures UPDATE: describes the warning-track exploitation, the new SRM WARNINGTRACK system configuration option, the new QUERY/SET SRM WARNINGTRACK options, and the new message variations on HCP1050E and HCP1051E. CHAPTER 3: Changes to External Interfaces SECTION: CP Changes SUBSECTION: System Configuration Statements TABLE 7: Changes to System Configuration Statements UPDATE: lists the new WARNINGTRACK operand on the SRM configuration statement and new message variation to HCP1051E. CHAPTER 3: Changes to External Interfaces SECTION: CP Changes SUBSECTION: CP Commands TABLE 9: Changes to CP Commands UPDATE: lists the new WARNINGTRACK operand on the QUERY and SET SRM commands along with the new message variation to HCP1050E for SET SRM WARNINGTRACK. *--------------------------------------------------------------* * PUBLICATION TITLE: z/VM: General Information * * RELEASE: z/VM 7.3 * * ORDER NUMBER: GC24-6286-73 * *--------------------------------------------------------------* SECTION: Summary of Changes for z/VM: General Information SUBSECTION: Hardware currency and exploitation UPDATE: lists changes made by the warning-track support. CHAPTER 2: What is new or changed in z/VM 7.3 SECTION: Product enhancements and other changes TABLE 1:Links to enhancement categories, availability, and descriptions UPDATE: the "Hardware currency and exploitation" category lists the new warning-track support. CHAPTER 2: What is new or changed in z/VM 7.3 SECTION: Hardware currency and exploitation UPDATE: describes the warning-track support. *--------------------------------------------------------------* * PUBLICATION TITLE: z/VM: VM Dump Tool * * RELEASE: z/VM 7.3 * * ORDER NUMBER: GC24-6335-73 * *--------------------------------------------------------------* SECTION: Summary of Changes for z/VM: VM Dump Tool UPDATE: lists the ability to format the new trace entries introduced by warning-track support. More information about the trace entries can be found in "z/VM Diagnosis Guide". ***END PUBLICATION CHANGE***************************************
APAR Information
APAR number
VM66678
Reported component name
VM CP CP
Reported component ID
568411202
Reported release
730
Status
CLOSED UR1
PE
NoPE
HIPER
NoHIPER
Special Attention
YesSpecatt / New Function / Xsystem
Submitted date
2023-03-17
Closed date
2023-11-03
Last modified date
2024-04-04
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UM90375
Modules/Macros
CPLOAD HCPABN HCPAFF HCPALL HCPAPI HCPAPJ HCPBVM HCPCFM HCPCKMST HCPCPA HCPCPU HCPCSA HCPDMP HCPDSB HCPDSP HCPDSX HCPEQUAT HCPEXT HCPHIP HCPIIO HCPISR HCPLCK HCPLGN HCPLMC HCPMCI HCPMCW HCPMDLAT HCPMES HCPMESB HCPMNE HCPMNU HCPMNY HCPMOM HCPMPC HCPMPG HCPMPS HCPMTO HCPMTS HCPMXL HCPMXRBK HCPPFXPG HCPPLSBK HCPQDO HCPRCC HCPRCCBK HCPRFI HCPRLG HCPRLU HCPRUN HCPSCJ HCPSEW HCPSGP HCPSNP HCPSNR HCPSRM HCPSRN HCPSSI HCPSTK HCPSTL HCPSTM HCPSTP HCPSXL HCPSXLBK HCPSYN HCPSYS HCPSYSCM HCPSZD HCPSZE HCPSZK HCPSZL HCPTHQ HCPTTA HCPTTABK HCPUSO HCPUSP HCPVMDBK HCPWAI HCPWRP HCPZPQ HCPZSD HCP1050E HCP1051E HCQTR730 HCWAI8 HCWA12 MRMTRSYS MRSCLSRM MRSYTPRP MRSYTSYG MRUSEACT MRUSELOF SRM
SC24627173 | SC24626873 | GC24628073 | SC24630173 | GC24629473 |
GC24628673 | GC24633573 | GC24627073 |
Fix information
Fixed component name
VM CP CP
Fixed component ID
568411202
Applicable component levels
R730 PSY UM90375
UP23/11/08 P 2401
Fix is available
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Document Information
Modified date:
04 April 2024