Entropy-based low power data TLB design

ABSTRACT

The Translation Look-aside Buffer (TLB), a content addressable memory, consumes significant power due to the associative search mechanism it uses in the virtual to physical address translation. Based on our analysis of the TLB accesses, we make two observations. First, the entropy or information content of the stack virtual page numbers is low due to high spatial locality of stack memory references. Second, the entropy of the higher order bits of global memory references is low since the size of the global data is determined and fixed during compilation of a program. Based on these two characteristics, we propose two techniques: an entropy-based speculative stack address TLB and a deterministic global address TLB to achieve energy reducing. Our results show an average of 47% energy savings in the data TLB with less than 1%overall performance impact.

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INDEX TERMS

Primary Classification:
  B. Hardware
  B.3 MEMORY STRUCTURES
      B.3.2 Design Styles
          Subjects: Virtual memory

Additional Classification:
  B. Hardware
  B.3 MEMORY STRUCTURES
      B.3.2 Design Styles
          Subjects: Associative memories

General Terms:
Design, Experimentation, Performance

Keywords:
entropy, low-power TLB, spatial and temporal locality