Efficient (stack) algorithms for analysis of write-back and sector memories

  • Authors:
  • James G. Thompson;Alan Jay Smith

  • Affiliations:
  • U.S. Air Force, Washington, DC;Univ. of California, Berkeley

  • Venue:
  • ACM Transactions on Computer Systems (TOCS)
  • Year:
  • 1989

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Abstract

For the class of replacement algorithms known as stack algorithms, existing analysis techniques permit the computation of memory miss ratios for all memory sizes simultaneously in one pass over a memory reference string. We extend the class of computations possible by this methodology in two ways. First, we show how to compute the effects of copy-backs in write-back caches. The key observation here is that a given block is clean for all memory sizes less than or equal to C blocks and is dirty for all larger memory sizes. Our technique permits efficient computations for algorithms or systems using periodic write-back and/or block deletion. The second extension permits stack analysis simulation for sector (or subblock) caches in which a sector (associated with an address tag) consists of subsectors (or subblocks) that can be loaded independently. The key observation here is that a subsector is present only in caches of size C or greater. Load forward prefetching in a sector cache is shown to be a stack algorithm and is easily simulated using our technique. Running times for our methods are only slightly higher than for a simulation of a single memory size using nonstack techniques.