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CPW and rPerf Explained: How to Actually Compare Power 11 Processor Options

Updated July 24, 2026

Every IBM Power 11 processor feature code carries a CPW (Commercial Processing Workload) rating, a rPerf (Relative Performance) rating, or both. Buyers who compare Power 11 configurations by core count alone are missing the number that actually predicts throughput.

What CPW measures

CPW is IBM's internal benchmark for IBM i commercial transaction processing, expressed as a relative index against a reference system. It is the standard IBM i sizing metric published in every IBM i sales manual and used by IBM i capacity planning tools.

What rPerf measures

rPerf is IBM's relative performance estimate for AIX and Linux workloads, derived from a mix of internal benchmarks and modeling. IBM publishes both single-threaded (rPerf ST) and SMT8 (8-way simultaneous multithreading) rPerf figures for many feature codes -- the SMT8 figure reflects realistic multi-partition throughput, while rPerf ST is closer to single-thread latency-sensitive performance.

A real example: S1122 processor options

S1122 CPW by feature code

Notice the 8-core eSCM posts a higher CPW than the 60-core DCM option -- CPW reflects the benchmarked feature, not core count alone.

Feature CodeCoresCPWrPerf SMT8
ERGR8-core eSCM236,400292.9
EBGA60-core DCM117,1001,531.9

Always compare CPW and rPerf figures within the same model and generation. Comparing a Power11 CPW figure against a Power10 or Power9 figure without adjusting for generational baseline changes will produce misleading conclusions -- see our Power10 vs Power 11 comparison for generation-normalized figures.

Sources

Related Models

IBM Power S1112 (9242-21B / 9242-21T)

The entry point into the IBM Power 11 generation: a single-socket, half-width 2U rack or tower system built for branch, edge, and smaller IBM i, AIX, and Linux deployments.

IBM Power S1122 (9824-22A)

A dense, dual-socket 2U scale-out server offering up to 60 Power 11 cores and 4 TB of DDR5 memory, IBM's mainstream choice for growing IBM i, AIX, and Linux environments.

IBM Power S1124 (9824-42A)

A quad-socket-capable, high-performance 4U scale-out server offering up to 60 Power 11 cores and 8 TB of DDR5 memory, built for enterprises and regional data centers.

IBM Power E1150 (9043-MRU)

A 4U enterprise scale-up server built for memory- and data-intensive AIX and Linux workloads, offering up to 120 Power 11 cores and 16 TB of DDR5 memory per node. Does not support IBM i.

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