A CPU Revolution - Sun's UltraSPARC T1 and T2 Processors

Sun Microsystems's new UltraSPARC T1 and T2 series of microprocessors has revived Sun's position as one of the few third-party manufactures capable of competing with the Big Two processor companies (Intel and AMD) who currently dominating the processor market. Sun fell behind for a few years as their flagship processor, the UltraSPARC IV series, hit its performance limits. But they have reentered the competition with their new UltraSPARC processors, completely redesigned from the ground up, and capable of new heights of power and flexibility.

The UltraSPARC T1 is the first processor produced by Sun that is both multicored and multithreaded. It first became available in 2005 with from four to eight CPU cores. Each core is capable of handling four threads at the same time. This means the processor as a whole is capable of handling anywhere from 16, 24, or even 32 threads simultaneously.

The UltraSPARC T1 is the first SPARC-based processor whose multiple cores can be partitioned. Several cores can be grouped together to work on a single task or set of tasks, while the remaining cores deal with the rest of the processes and threads. Furthermore, the UltraSPARC T1 supports the Hyper-Privileged execution mode, which means that it can partition its cores into as many as 32 logical domains (one for each thread in an eight-CPU system). Each of these logical domains could run its own operating system instance (usually Solaris).

The only drawback to the UltraSPARC T1 is that it is only available in uniprocessor systems, which limits its vertical scalability in large business networks. The UltraSPARC T2, released in late 2007, addressed his problem amidst many other advances and improvements.

The UltraSPARC T2 is in many ways a souped-up TI. It contains eight CPU cores, and each core is capable on handling eight threads each, for a total of 64 threads being handled simultaneously. This is double the maximum capacity of the T1, which toped out at 32 concurrent threads. Also like the T1, the T2 supports Hyper-Privileged execution mode. Whereas the T1 could only partition its cores into 32 logical domains, the T2, with more cores available, can partition them into 64 logical domains. Furthermore, a two-way SMP T2+ system can be partitioned into as many as 128 logical domains, each capable of running an instance of Solaris.

In addition to doing everything the T1 does (only better), the T2 also had several new features. Among other things, it had increased thread scheduling and instruction prefetching, allowing it to achieve a higher single-threaded performance. It also increased the processing speed for each thread from 1.2 for the T1 to 1.4 GHz. While the T1 has a Jbus interface, the T2 has a PCI Express port. The L2 cache on the T2 was increased to 4 MB (as opposed to the T1's 3 MB). It has four dual-channel FBDIMM memory controllers, and eight encryption engines. In early 2008, Sun released a new UltraSPARC T2 Plus processor, which is an SMP-capable version of the UltraSPARC T2.

Sun MicroSystems' UltraSPARC T1 and T2 prove that, despite increasing competition from Intel and AMD, Sun is still in the processor race, particularly in the high-end server processor market. Sun's designs continue to be innovative and, as the core partitioning system demonstrates, flexible.

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