Memory Access - IBM Power 750 Technical Overview And Introduction

Figure 2-3 shows the evolution of simultaneous multithreading in the industry.
Multi-threading evolution
1995 Single thread out of order
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Figure 2-3 Evolution of simultaneous multithreading
The various SMT modes offered by the POWER7+ processor allow flexibility, enabling users
to select the threading technology that meets an aggregation of objectives such as
performance, throughput, energy use, and workload enablement.
Intelligent Threads
The POWER7+ processor features Intelligent Threads that can vary based on the workload
demand. The system either automatically selects (or the system administrator can manually
select) whether a workload benefits from dedicating as much capability as possible to a
single thread of work, or if the workload benefits more from having capability spread across
two or four threads of work. With more threads, the POWER7+ processor can deliver more
total capacity as more tasks are accomplished in parallel. With fewer threads, those
workloads that need fast individual tasks can get the performance that they need for
maximum benefit.

2.1.4 Memory access

Each POWER7+ processor chip has one memory controller that uses two memory channels.
Each memory channel operates at 1066 MHz connects to four DIMMs.
In the Power 750 server, each channel can address up to 64 GB. Thus, the Power 750 is
capable of addressing up to 1 TB of total memory.
In the Power 760 server, each channel can address up to 128 GB. Thus, the Power 760 is
capable of addressing up to 2 TB of total memory.
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IBM Power 750 and 760 Technical Overview and Introduction
2004 2-way SMT
Thread 0 Executing
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1997 Hardware multi-thread
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2010 4-way SMT
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