JETTY: Filtering snoops for reduced energy consumption in SMP servers

Andreas Moshovos*, Gokhan Memik, Babak Falsafi, Alok Choudhary

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

127 Scopus citations


We propose methods for reducing the energy consumed by snoop requests in snoopy bus-based symmetric multiprocessor (SMP) systems. Observing that a large fraction of snoops do not find copies in many of the other caches, we introduce JETTY, a small, cache-like structure. A JETTY is introduced in-between the bus and the L2 backside of each processor. There it filters the vast majority of snoops that would not find a locally cached copy. Energy is reduced as accesses to the much more energy demanding L2 tag arrays are decreased. No changes in the existing coherence protocol are required and no performance loss is experienced. We evaluate our method on a 4-way SMP server using a set of shared-memory applications. We demonstrate that a very small JETTY filters 74% (average) of all snoop-induced tag accesses that would miss. This results in an average energy reduction of 29% (range: 12% to 40%) measured as a fraction of the energy required by all L2 accesses (both tag and data arrays).

Original languageEnglish (US)
Title of host publicationIEEE High-Performance Computer Architecture Symposium Proceedings
Number of pages12
StatePublished - Jan 1 2001
Event7th International Symposium on High-Performance Computer Architecture - Nuevo Leon, Mex
Duration: Oct 20 2000Oct 24 2000


Other7th International Symposium on High-Performance Computer Architecture
CityNuevo Leon, Mex

ASJC Scopus subject areas

  • General Engineering


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