Decomposing the Load-Store Queue by Function for Power Reduction and Scalability

Baugh, Lee W.; Zilles, Craig

Permalink

https://hdl.handle.net/2142/11109 Copy

Description

Title

Decomposing the Load-Store Queue by Function for Power Reduction and Scalability

Author(s)

• Baugh, Lee W.
• Zilles, Craig

Issue Date

2005-10

Keyword(s)

computer science

Abstract

Because they are based on large content-addressable memories, load-store queues (LSQs) present implementation challenges in superscalar processors, especially as issue width and number of in-flight instructions are scaled. In this paper, we propose an alternate organization of an LSQ that separates the time-critical forwarding functionality from checking that loads received their correct values. Two main techniques are exploited: 1) the store forwarding logic is only accessed by those loads and stores that are likely to be involved in forwarding, and 2) the checking structure is banked by address. The result of these techniques is that a collection of small, low bandwidth structures can be substituted for the large, high bandwidth structures used in conventional designs. By our calculations, these proposed techniques reduce LSQ dynamic power by a factor of 3-5 while achieving equivalent performance. Furthermore, we explore applying these techniques to processors requiring only statistical correctness guarantees where another factor of two power reduction is achievable.

Type of Resource

text

Permalink

http://hdl.handle.net/2142/11109

Copyright and License Information

You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the University of Illinois at Urbana-Champaign Computer Science Department under terms that include this permission. All other rights are reserved by the author(s).

Owning Collections