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Supercomputer Upgrade
From Cray T3D to Cray T3E
During the week of January 21, 1997
Institute researchers said farewell to the Cray T3D supercomputer and began computing
on a new Cray-T3E system. Like the T3D, the T3E is operated for the Institute by
Minnesota Supercomputer Center Inc. With this upgrade, Institute users have access
to several capabilities that are unique to the Cray-T3E and differentiate it from
other parallel systems. Benchmarks have shown that relative performance of the T3E
with respect to the T3D is greater than what would be expected from the factor of
two increase in processor speed alone.
There are several T3E hardware features that contribute to this performance improvement.
The major features include the addition of a 96 kilobyte secondary cache, one processor
per network node (the T3D had two), and new circuitry to control the microprocessor’s
local and remote memory operations.
The new control circuitry, referred to as the C-chip, greatly enhances the bandwidth
of memory to microprocessor communication, and performs important bookkeeping operations
to maintain interprocessor cache coherence. It also contains 512 E-registers that
are used to send and receive interprocessor messages and also perform synchronization
operations.
The other new performance enhancing feature of the C-chip is the implementation of
stream buffers which work to increase local memory bandwidth by providing the microprocessor
with the data it has requested without stalling.
In addition to the performance improvements, probably the most obvious change prior
T3D users will experience is in the operating system. The T3E is "self-hosted"
where users log directly into the system, rather than access it through a front-end
machine. This is a convenience feature for UNIX users who can now be directly on
the system, but more importantly it allows for greatly enhanced input/output performance.
These operations are now processed through multiple input/output ports.
The initial T3E configuration that we have available is air-cooled and contains 68
processors, 64 of which are for user applications. The other four processors service
operating system requests. Each processor has 128 megabytes of local memory.
This latest upgrade of supercomputing resources at the Minnesota Supercomputer Center
Inc. continues a tradition of operating and making available to the University of
Minnesota research community the most advanced supercomputer architectures. Allocations
of computer resources on the Cray T3E are available to faculty at institutions of
higher education in the state of Minnesota and are also used by their students and
research collaborators. |
