Theta

Theta, a 9.65 petaflops system based on the second-generation Intel® Xeon Phi™ processor, will enable breakthrough computational science and engineering research, while providing an early production system to help ALCF users transition their applications to the new Intel Xeon Phi architecture.

Designed in collaboration with Intel and Cray, Theta will serve as a bridge between the ALCF’s current supercomputer, Mira, and its next leadership-class supercomputer, Aurora. Both Theta and Aurora will be massively parallel, many-core systems based on Intel processors and interconnect technology, a new memory architecture, and a Lustre-based parallel file system, all integrated by Cray’s HPC software stack.

Theta is equipped with 3,624 nodes, each containing a 64 core processor with 16 gigabytes (GB) of high-bandwidth in-package memory (MCDRAM), 192 GB of DDR4 RAM, and a 128 GB SSD. Theta’s initial parallel file system is 10 petabytes.

While Theta’s peak speed is slightly less than Mira’s, the new system has several features that will allow scientific codes to achieve higher performance. These features include:

  • High-bandwidth MCDRAM (300 - 450 GB/s depending on memory and cluster mode), with many applications running entirely in MCDRAM or using it effectively with DDR4 RAM
  • Improved single thread performance
  • Potentially much better vectorization with AVX-512
  • Large total memory per node (208 GB on Theta vs. 16 GB on Mira)

Theta System Configuration

  • 20 racks
  • 3,624 nodes
  • 231,935 cores
  • 56 TB MCDRAM
  • 679 TB DDR4
  • 453 TB SSD
  • Aries interconnect with Dragonfly configuration
  • 10 PB Lustre file system
  • Peak performance of 9.65 petaflops