Sun Microsystems Inc.s new chip multithreading technology is designed to provide maximum throughput for network computing workloads. Featured in the latest UltraSPARC IV processors used in new Sun Fire servers, CMT technology lets Sun processors run two concurrent threads per CPU.
The UltraSPARC IV CMT processors provide as much as twice the throughput of previous-generation UltraSPARC III processors. In fact, the UltraSPARC IV processor has two integrated UltraSPARC III cores on the same die, and each core has 8MB of dedicated Level 2 cache and a memory controller.
The new UltraSPARC IV processor also offers two 14-stage instruction pipelines, one for each thread. Each stage in the pipeline handles part of the work required in executed instruction.
The performance implications of a deep pipeline system are apparent when an event such as a data-cache miss occurs. A traditional CPU design will issue a global stall signal, freezing the entire pipeline and incurring a performance hit.
In the UltraSPARC IV processor, on the other hand, the event is handled more like a trap: The pipeline gets flushed, and the state is restored by refetching instructions from the first stage of the pipeline.
The Sun Fire enterprise servers we reviewed can accommodate as many as eight UltraSPARC IV processors, and high-end Sun Fire systems can scale as high as 72 UltraSPARC IV processors, providing a powerful computational platform that supports a maximum of 144 concurrent threads.
Going forward, the companys Sun Fire enterprise servers and Solaris are positioned to take advantage of multithread computing. Sun officials said they plan to scale their CMT processors to handle up to 10 times the number of threads per CPU compared with current offerings.
Suns CMT architecture for high-throughput computing will enable IT managers to save costs and achieve much-higher-level performance in products ranging from databases and Web servers to high-performance computing and application development environments.