A CPU Revolution: Sun’s UltraSPARC T1 and T2 Processors
Sun Microsystems’ new UltraSPARC T1 and T2 microprocessor series have revived Sun’s position as one of the few third-party manufacturers capable of competing with the two large processor companies (Intel and AMD) that currently dominate the processor market. Sun was left behind for a few years when its flagship processor, the UltraSPARC IV series, reached its performance limits. But they have reentered the competition with their new UltraSPARC processors, completely redesigned from the ground up and capable of reaching new heights of power and flexibility.
The UltraSPARC T1 is the first processor produced by Sun that is both multi-core and multi-threaded. It was first available in 2005 with four to eight CPU cores. Each core is capable of handling four threads at the same time. This means that the processor as a whole is capable of handling from 16, 24 or even 32 threads simultaneously.
The UltraSPARC T1 is the first SPARC-based processor whose multiple cores can be partitioned. Multiple cores can be grouped together to work on a single task or set of tasks, while the remaining cores take care of the rest of the processes and threads. Additionally, the UltraSPARC T1 supports Hyper-Privileged execution mode, which means that it can divide its cores into up to 32 logical domains (one for each thread in an eight CPU system). Each of these logical domains could run its own OS instance (typically Solaris).
The only downside to the UltraSPARC T1 is that it is only available on single-processor systems, which limits its vertical scalability in large commercial networks. The UltraSPARC T2, released in late 2007, addressed its problem amid many other advancements and enhancements.
The UltraSPARC T2 is in many ways an improved IT. It contains eight CPU cores, and each core is capable of handling eight threads each, for a total of 64 threads that are handled simultaneously. This is twice the maximum capacity of T1, which reached 32 concurrent threads. Also like the T1, the T2 supports Hyper-Privileged execution mode. While T1 could only divide its cores into 32 logical domains, T2, with more cores available, can divide them into 64 logical domains. Additionally, a bidirectional SMP T2 + system can be divided into up to 128 logical domains, each of which can run a Solaris instance.
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 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 T2 was increased to 4MB (as opposed to 3MB on T1). 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-compliant version of the UltraSPARC T2.
Sun MicroSystems’ UltraSPARC T1 and T2 demonstrate 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 central partition system demonstrates, flexible.