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October 28, 2015: Hexagon has been upgraded to 15 nodes.

September 30, 2014: The Sherrill group has created the Hexagon cluster for dedicated group computations. Each node is powered by an Intel Core i7 hexa-core CPU, of the x930K series. Large-memory computations are facilitated by the availability of 64GB per node. These resources are in addition to similarly-configured workstations throughout the lab, and access to the resources of CCMST and PACE. The cluster was constructed by Trent Parker, Matt Kennedy, and David Sherrill.

Cluster Specifications
Compute Nodes 15
Cores 90
Memory 960 GB
Scratch Space 135 TB
6-core 5930K nodes, 64GB @3.5-3.7GHz 8
6-core 4930K nodes 64GB @3.6-3.9GHz 6
6-core 3930K nodes 64GB @3.5-3.8GHz 1
4-core 4790K head node 32GB @4.0-4.4GHz 1
NVIDIA K40 GPU, 12 GB DDR5 RAM 1 (hex9)

Speedups due to Haswell FMA instructions

Two of the nodes feature new 5930K Haswell CPU's, which have a fused multiply-add (FMA) instruction, allowing a potential doubling of speed for matrix multiplies. In practice we see about a 1.8X speedup in DGEMM using OpenBLAS, and about a 1.4X speedup in one of our timings tests for CCSD(T) using the DF-CCSD(T) code in Psi4.

Comparison of Haswell OpenBLAS (FMA-enabled, red), an older (non-FMA-enabled) MKL library (green), and Haswell running OpenBLAS compiled for Sandybridge (i.e., without FMA support, blue)

Sandwich Benzene Dimer DF-CCSD(T)/cc-pVDZ Wall Times (seconds) Using 6 Cores
4930K (3.9GHz) MKL 10.3 1712
4930K (3.9GHz) MKL 11.2 1601
5930K (3.7GHz) MKL 10.3 1446
5930K (3.7GHz) MKL 11.2 (with FMA) 1097

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