A fix is available
APAR status
Closed as new function.
Error description
z/VM spinlock performance improvements
Local fix
N/A
Problem summary
**************************************************************** * USERS AFFECTED: Systems experiencing more than 10% system * * overhead with indications of high spinlock * * overhead for SRMSLOCK, HCPTRQLK, or DSVLOCK. * **************************************************************** * PROBLEM DESCRIPTION: * **************************************************************** * RECOMMENDATION: APPLY PTF * **************************************************************** This APAR provides improvements to reduce system overhead from the Scheduler Lock (SRMSLOCK), TRQBK Queue Lock (HCPTRQLK),and Dispatch Vector Lock (DSVLOCK). Systems experiencing more than 10% system overhead with indications that SRMSLOCK, HCPTRQLK or DSVLOCK spinlock contention are a significant factor. This contention is observed as high levels of spin time on these locks, or high rates of DIAG x'9C' issued from HCPDSP. Perfkit LOCKACT report FCX326 and Monitor record D0R23 MRSYTLCK provides information on spinlocks including SRMSLOCK, HCPTRQKLK and DSVLOCK. Perfkit PROCSUM report FCX239 and Monitor record D0R13 MRSYTSCP provides information on the rate of Diagnose 9C issued by HCPDSP.
Problem conclusion
Temporary fix
Comments
With the PTF for APAR VM65988, the z/VM hypervisor has been enhanced to manage its spinlocks more efficiently and thereby reduce system overhead. This enhancement will contribute to improved performance and throughput and thereby help to improve overall system capacity by allowing additional work to be performed. While most workload configurations could benefit to some extent, the improvements are greatest for workloads using a larger number of logical CPUs. The shared-exclusive spinlock manager was redesigned to use more cache-efficient data structures and algorithms which reduce the likelihood of lock contention for the Scheduler Lock (SRMSLOCK) and Topology Lock (HCPDSVTL). This new spinlock design is not dependent on new processor architecture. A new Monitor sample record D5R22 MRPRCSXL "Shared-Exclusive Spinlock Utilization" was added to provide a more detailed reporting of the usage of the new shared-exclusive spinlocks on a per-processor basis. However, the new shared-exclusive spinlock manager statistics are reported in the existing Monitor D0R23 MRSYTLCK record in a compatible manner. The time spent spinning in HCPDSP's internal spin loop used to acquire a share of the Scheduler Lock was previously unreported as spinlock spin time. It is now included in SRMSLOCK reporting in Monitor D0R23 MRSYTLCK, SYTPRP_PFXSPINT in Monitor D0R2 MRSYTPRP, as well as the new D5R22 MRPRCSXL sample record. This internal spinloop in HCPDSP was made more efficient as part of the shared-exclusive spinlock manager redesign. In partitions with shared processors the only external indicator of SRMSLOCK contention in HCPDSP was the Diagnose 9C rate issued from HCPDSP as reported in Perfkit PROCSUM report FCX239 and Monitor record D0R13 MRSYTSCP. With this improvement the reported SRMSLOCK spin time may increase somewhat, but time spent in HCPDSP should be reduced. Reduced time in HCPDSP should result in lower System time. A reduction in the Diagnose 9C rate from HCPDSP is expected. The HCPTRQLK and DSVLOCK exclusive-only spinlock algorithms have been adjusted to operate best on D/T3906 and D/T3907 hardware without causing degradation when running on older models. The support is available on all hardware supported by z/VM V6.4, including D/T3906 LinuxONE Emperor II and IBM z14. However, the improvements for HCPTRQLK and DSVLOCK depend on efficiencies unique to the LinuxONE Emperor II and z14. The following publications have been updated: - GC24-6177-10, z/VM: CP Messages and Codes - SC24-6208-09, z/VM: Performance - GC24-6201-12, z/VM: Migration Guide - GC24-6187-07, z/VM: Diagnosis Guide - SC24-6175-11, z/VM: CP Commands and Utilities Reference
APAR Information
APAR number
VM65988
Reported component name
VM CP
Reported component ID
568411202
Reported release
640
Status
CLOSED UR1
PE
NoPE
HIPER
NoHIPER
Special Attention
YesSpecatt / New Function / Xsystem
Submitted date
2017-02-06
Closed date
2017-08-23
Last modified date
2019-10-18
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UM35214
Modules/Macros
CBITABLE CPLOAD HCPAEP HCPAFF HCPAFR HCPAFS HCPALD HCPALF HCPALG HCPALL HCPALR HCPALU HCPAMD HCPAMI HCPAMP HCPAMR HCPAPI HCPAPJ HCPASERT HCPASR HCPASRBK HCPBMS HCPBUT HCPBVM HCPCBI HCPCCF HCPCFM HCPCORBK HCPCPA HCPCPU HCPCRS HCPCSA HCPCUP HCPCVT HCPDSB HCPDSP HCPDSV HCPDSVBK HCPEQUAT HCPFRD HCPFRE HCPFRF HCPGRB HCPHAS HCPHAT HCPHIC HCPHIP HCPHIP$ HCPHIS HCPHPC HCPHRU HCPHTF HCPHVR HCPICU HCPIOJ HCPISM HCPISR HCPIST HCPKCL HCPKCT HCPKCW HCPLAN HCPLGN HCPLKCOR HCPLKPLD HCPLKSCH HCPLKTOP HCPLKTRQ HCPLMC HCPLOC HCPLOCBK HCPMCI HCPMCS HCPMCW HCPMDLAT HCPMNP HCPMNU HCPMOL HCPMOM HCPMONEQ HCPMOP HCPMOT HCPMPC HCPMPF HCPMPS HCPMSM HCPMTC HCPMTF HCPMTO HCPMTS HCPNDM HCPNOO HCPNSC HCPNSR HCPOBTN HCPOM1 HCPOM2 HCPPAF HCPPAH HCPPAI HCPPFE HCPPFR HCPPFX HCPPFXPG HCPPGC HCPPGT HCPPGU HCPPLP HCPPLSBK HCPPOD HCPPOOLS HCPPPGMS HCPPPI HCPPPR HCPPTA HCPPTC HCPPTE HCPPTF HCPPTG HCPPTM HCPQDO HCPQFL HCPQPT HCPQSX HCPRCC HCPRCCBK HCPRDA HCPRDD HCPRFI HCPRLB HCPRLG HCPRLI HCPRLSE HCPRLU HCPRP HCPRSM HCPSAM HCPSCI HCPSCJ HCPSGP HCPSHI HCPSMO HCPSNR HCPSPC HCPSRM HCPSRMBK HCPSRN HCPSSI HCPSTK HCPSTL HCPSTM HCPSTP HCPSTQ HCPSUBBK HCPSVC HCPSVD HCPSVU HCPSXA HCPSXL HCPSXLBK HCPSXLLK HCPSXLUL HCPSXP HCPSXU HCPSYN HCPSYN$ HCPSYNBK HCPSYNC HCPSZD HCPSZE HCPSZK HCPSZL HCPTDK HCPTHQ HCPTMF HCPTRQ HCPTTA HCPTTABK HCPTZN HCPUDR HCPULCOR HCPULPLD HCPULSCH HCPULTOP HCPULTRQ HCPUSYNC HCPVFM HCPWAI HCPXCM HCPXHC HCPXHD HCPXHE HCPXRC HCPXRP HCPXTM HCPXTR HCPZPC HCPZPQ HCWAI8 HCWA12 MRPRCSXL MRSYTLCK MRSYTPRP MRSYTSCG MRSYTSCP SUBBKS
GC24617710 | SC24620809 | GC24620112 | GC24618707 | SC24617511 |
Fix information
Fixed component name
VM CP
Fixed component ID
568411202
Applicable component levels
R640 PSY UM35214
UP17/08/30 P 1802
Fix is available
Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.
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Document Information
Modified date:
18 October 2019