Reporting and Analysis of IBM’sCPU Measurement Facility Data

Philadelphia CMGSeptember 14, 2012

Bill SheldenBill.Shelden@PerfTechPro.com

• Introduction• CPU Measurement Facility• Using the SMF 113 records

• Data from a 2097-706 (z10)• Relative Nest Intensity• Matching LSPR Workloads (LOW, AVG, HIGH)

• Data from a 2818-Y02 (z114)• MIPS Reasonability Check• CPU Capacity Planning Checklist• Conclusions• PerfTechPro Offer

Topics

• CPU MF - 2012 Update and WSC Experiences for SHARE Atlanta Final.pdf

• CPU MF Webinar Part 1 May 2 Final.pdf• CPU MF Webinar Part 2 June 14 Final.pdf• Peter.Enrico.Exploring.SMF113.and.CPU.Counters.pdf• SA23-2260-02 The Load-Program-Parameter and the

CPU-Measurement Facilities.pdf• SA23-2261-01 IBM The CPU-Measurement Facility

Extended Counters Definition for z10 and z196.pdf

References

• Introduced in z10 and later processors • New facility that provides hardware instrumentation data for production

systems• Two Major components

• Counters• Cache and memory hierarchy information • SCPs supported include z/OS and z/VM

• Sampling• Instruction time-in-CSECT

• New z/OS HIS started task• Gathered on an LPAR basis• Writes SMF 113 records

• New z/VM Monitor Records• Gathered on an LPAR basis – all guests are aggregated• Writes new Domain 5 (Processor) Record 13 (CPU MF Counters) records

• Minimal overhead

Introduction - CPU Measurement Facility

• Counters are cumulative• Need to compute deltas between records

• Cut on the SMF accounting interval• Not the RMF interval

• Records pertain to a specific LPAR

Introduction – Using the SMF113 records

Data from a 2097-706 (z10)

Cycles Per Instruction

Level 1 Miss %

% of L1 Misses Sourced from Memory

Instruction Sourcing Profile (of L1 Misses)

Relative Nest Intensity

• Some Definitions:• L2LP = % from Level 2 Local cache (same book)• L2RP = % from Level 2 Remote cache (different book)• L3P = % from Level 3 cache• L4LP = % from Level 5 Local cache (same book)• L4RP = % from Level 4 Remote cache (different book) • MEMP = % sourced from Memory

• RNI - Reflects the distribution and latency of sourcing from shared caches and memory• For z10 EC and BC:

• RNI = (1.0*L2LP + 2.4*L2RP + 7.5*MEMP) / 100 • For z196 / z114:

• RNI = 1.6*(0.4*L3P + 1.0*L4LP + 2.4*L4RP + 7.5*MEMP) / 100

Relative Nest Intensity

L1MP < 3% RNI>0.75 AVERAGERNI<0.75 LOW

3%<L1MP<6% RNI>1.0 HIGH0.6<RNI<1.0 AVERAGERNI<0.6 LOW

L1MP>6% RNI>0.75 HIGHRNI<0.75 AVERAGE

RNI-based LSPR Workload Decision Table

Matching LSPR Workloads (LOW, AVG, HIGH)

Data from a 2818-Y02 (z114)

Cycles Per Instruction

Level 1 Miss %

% of L1 Misses Sourced from Memory

Instruction Sourcing Profile (of L1 Misses)

Matching LSPR Workloads (LOW, AVG, HIGH)

RNI may be Load dependent

0:291:29

2:293:29

4:295:29

6:297:29

8:299:29

10:2911:29

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Relative Nest IntensitiesSYSB (2818-Y02) SYSA (2097-706)

0:001:30

3:004:30

6:007:30

9:0010:30

12:0013:30

15:0016:30

18:0019:30

21:0022:30

0

200

400

600

800

1000

1200

MIPS UsedSYSB (2818-Y02) SYSA (2097-706)

Relative Nest Intensity

MIPS Reasonability Check

• From CPU Table (LOW RNI)• GPP ‘MIPS’ = 5045.60• ‘MIPS’/GPP = 5045.60 / 6 = 841 ‘MIPS’/GPP

• For 9:59 AM which is a LOW RNI interval• 3.54 Cycles per Instruction• 4.4 Cycles per nanosecond (per GPP)• 4.4 / 3.54 = 1.24 Instructions per Nanosecond• 1.24 x 1,000,000,000 Instructions per Second• 1.24 x 1000 = 1240 MIPS/GPP

MIPS Reasonability Check

• Collect CPU Measurement Facility Data for all ‘important’ LPARs

• For each LPAR:• Determine RNI-based LSPR workload mix

among LOW, AVG or HIGH• Determine MIPS values for current and

contemplated CPUs based on RITRs for RNI-based LSPR workload mix just determined• Use IBM’s zPCR to account for specific LPAR

configuration

CPU Capacity Planning Checklist

• Great insights into hardware and workload relationship

• RNI May be load dependent• More accurate CPU capacity planning

Conclusions

• Send us some of your data:• 24 hours of data• RMF 70, 71, 72, 73, and 75s• SMF 113s from one LPAR

• We will:• Return a set of charts in a PDF• Discuss your results on a WebEx

• Contact Bill Hart at bill.hart@perftechpro.com

PerfTechPro Offer