Investigating the TLB Behavior of High-end Scientific Applications on Commodity Microprocessors

The floating point portion of the SPEC CPU suite and the HPC Challenge suite are widely recognized and utilized as benchmarks that represent scientific application behavior. In this work we show that while these benchmark suites may be representative of the cache behavior of production scientific applications, they do not accurately represent the TLB behavior of these applications. Furthermore, we demonstrate that the difference can have a significant impact on performance. In the first part of the paper we present results from implementation-independent trace-based simulations which demonstrate that benchmarks exhibit significantly different TLB behavior for a range of page sizes than a representative set of production applications. In the second part we validate these results on the AMD Opteron implementation of the x86 architecture, showing that false conclusions about choice of page size, drawn from benchmark performance, can result in performance degradations of up to nearly 50% for the production applications we investigated..