Performance comparison of Intel Xeon Phi Knights Landing

Abstract

The Intel Xeon Phi is a many-core processor with a theoretical peak performance of over 3 TFLOP/s of double precision. We contrast the performance of the second-generation Intel Xeon Phi, code-named Knights Landing (KNL), to the first-generation Intel Xeon Phi, codenamed Knights Corner (KNC), as well as to a node with two multi-core CPUs as baseline reference. The test code solves the classical elliptic test problem of the Poisson equation whose performance is prototypical for the computational kernel in many numerical methods for partial differential equations. The results show that the KNL can perform approximately four times faster than the KNC or than two CPUs, provided the problem fits into the 16 GB of on-chip MCDRAM memory of the KNL. The studies also confirm the nominal five times faster speed of the new high-performance MCDRAM memory in the KNL compared to the DDR4 memory of the node. We demonstrate the ease of porting code to the KNL by focusing on performance that was achieved by only re-compiling hybrid MPI+OpenMP code with a KNL flag.