A number of observations arise out of the experience gained at the CEA’s HPC complex over the past 10 years.
Increasing user requirements have resulted in a rapid increase in demand for processing power and data management capabilities. Changing physical models are generating significantly larger flows of data from the computer to the storage and visualisation systems.
Moore’s law on the rate of technological advancement in microprocessors is no longer yielding increases in processor frequency, but increases in the number of cores per processor.
The power of individual processors remains essentially constant; currently, the only way to increase a computer’s processing power is to scale the number of processors.
Clearly, developing future generations of supercomputers calls for disruptive technologies, in particular in the area of electric power consumption management. To this end, the CEA decided to adopt a pro-active co-design methodology for future computers, alongside Atos/Bull, with which the CEA has built up a partnership over more than a decade.
The agreement between CEA and Atos/Bull to develop an exascale supercomputer by 2020 sets out the R&D objectives that must be achieved in order to address major challenges in areas such as energy performance, operating reliability and mass interconnection.
All of the objectives in terms of prerequisites for building a pre-exascale industrial demonstrator have now been achieved. The initial-phase version of Tera1000 installed in late 2015 not only demonstrated a theoretical processing power double that of Tera100, but also reduced its electric power consumption by a factor of five.
The second phase, realised in 2017, yield an operational Tera1000 supercomputer with processing power of 25 Pflops and electric power consumption unchanged from Tera100, representing a 20-fold gain in energy efficiency.