Chapter 2. Architecture and technical overview
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2.1.2 processor core
Each processor core implements aggressive out-of-order (OoO) instruction
execution to drive high efficiency in the use of available execution paths. The
processor has an Instruction Sequence Unit that is capable of dispatching up to six
instructions per cycle to a set of queues. Up to eight instructions per cycle can be issued to
the instruction execution units. The processor has a set of 12 execution units:
Two fixed point units
Two load store units
Four double precision floating point units
One vector unit
One branch unit
One condition register unit
One decimal floating point unit
The following caches are tightly coupled to each processor core:
Instruction cache: 32 KB
Data cache: 32 KB
L2 cache: 256 KB, implemented in fast SRAM
2.1.3 Simultaneous multithreading
processors support SMT1, SMT2, and SMT4 modes to enable up to four
instruction threads to execute simultaneously in each processor core. The
processor supports the following instruction thread execution modes:
SMT1: Single instruction execution thread per core
SMT2: Two instruction execution threads per core
SMT4: Four instruction execution threads per core
SMT4 mode enables the processor to maximize the throughput of the processor
core by offering an increase in processor-core efficiency. SMT4 mode is the latest step in an
evolution of multithreading technologies introduced by IBM.
Maximum execution threads (core/chip)
4/32
Maximum L2 cache (core/chip)
256 KB/2 MB
Maximum On-chip L3 cache (core/chip)
10 MB/80 MB
DDR3 memory controllers
1
SMP design-point
32 sockets with IBM processors
Compatibility
With prior generation of POWER processor
Technology
processor
