Rock processor
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| Designed by | Sun Microsystems |
|---|---|
| Instruction set | SPARC V9 |
| Cores | 16 |
Rock (or ROCK) was a multithreading, multicore, SPARC microprocessor under development at Sun Microsystems. Now canceled, it was a separate project from the SPARC T-Series (CoolThreads/Niagara) family of processors.
Rock aimed at higher per-thread performance, higher floating-point performance, and greater SMP scalability than the Niagara family. The Rock processor targeted traditional high-end data-facing workloads, such as back-end database servers, as well as floating-point intensive high-performance computing workloads, whereas the Niagara family targets network-facing workloads such as web servers.
The Rock processor implements the 64-bit SPARC V9 instruction set and the VIS 3.0 SIMD multimedia instruction set extension. Each Rock processor has 16 cores, with each core capable of running two threads simultaneously, yielding 32 threads per chip. Servers built with Rock use FB-DIMMs to increase reliability, speed and density of memory systems. The Rock processor uses a 65 nm manufacturing process for a design frequency of 2.3 GHz. The maximum power consumption of the Rock processor chip is approximately 250 W.
The 16 cores in Rock are arranged in four core clusters. The cores in a cluster share a 32 KB instruction cache, two 32 KB data caches, and two floating point units. Sun designed the chip this way because server workloads usually have high re-utilization in data and instruction across processes and threads but low number of floating-point operations in general. Thus sharing hardware resources among the four cores in a cluster leads to significant savings in area and power but low impact to performance.
In 2005, Sun publicly disclosed a feature in the Rock processor called hardware scout. Hardware scout uses otherwise idle chip execution resources to perform prefetching during cache misses.
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