Ultra SPARC T1 - Weaknesses

Weaknesses

The T1 only offered a single Floating Point unit to be shared by the 8 cores, limiting usage in HPC environments. This weakness was mitigated with the follow-on UltraSPARC T2 processor, which included 8 floating point units, as well as other additional features.

The T1 was only available in uniprocessor systems, limiting vertical scalability in large enterprise environments. This weakness was mitigated with the follow-on "Victoria Falls", commercially known as the UltraSPARC T2 Plus, as well as the next generation SPARC T3 and SPARC T4. The UltraSPARC T2+, SPARC T3, and SPARC T4 all offer single, dual, and quad socket configurations.

The T1 had outstanding throughput with massive numbers of threads supported by the processor, but older applications burdened with single thread bottlenecks occasionally exhibited poor overall performance. Single threaded application weakness was mitigated with the follow-on SPARC T4 processor. The T4 core count was reduced to 8 (from 16 on the T3), the cores were made more complex, the clock rate was nearly doubled - all contributing to faster single thread performance (from between 300% to 500% increase over previous generations. Additional effort was made to add the "critical thread API", where the operating system would detect a bottleneck and would temporarily allocate the resources of an entire core, instead of a 1 of 8 threads, to the targeted application processes exhibiting single threaded CPU bound behavior. This allowed the T4 to uniquely mitigate single threaded bottlenecks, while not having to compromise in the overall architecture to achieve massive multi-threaded throughput.