Sun Microsystems SPARC T5220 - Manual (Page 15)

13 The UltraSPARC T2 Processor with CoolThreads Technology Sun Microsystems, Inc.
simply increasing the number of cores would have gained additional throughput, but
would have resulted in consuming extra die area, leaving no room for integrated
components such as floating point processors.
The final UltraSPARC T2 processor design recognizes that memory latency is truly the
bottleneck to improving performance. By increasing the number of threads supported
by each core, and by further increasing network bandwidth, the UltraSPARC T2 is able
provide approximately twice the throughput of the UltraSPARC T1 processor. Each
UltraSPARC T2 processor provides up to eight cores, with each core able to switch
between up to eight threads (64 threads per processor). In addition, each core provides
two integer execution units, so that a single UltraSPARC core is capable of executing
two threads at a time. Figure 4 provides a simplified high-level illustration of the thread
model supported by an eight-core UltraSPARC T2 processor.
Figure 4. A single eight-core UltraSPARC T2 processor supports up to 64 threads, with up to two threads
running in each core simultaneously
Core 1
Thread 1
Thread 8
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Core 2
Core 3
Core 4
Core 5
Core 6
Core 7
Core 8
Time Memory Latency Compute
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Thread 8
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Thread 1
Thread 8
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Thread 1
Thread 8
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Thread 1
Thread 8
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Thread 1
Thread 8
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Thread 1
Thread 8
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Thread 1
Thread 8
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