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Cache Size


Tables 3 and 4 compare the performance of the DEAR scheme against the LRU scheme for various buffer cache sizes for the single and multiple application cases, respectively. The results from the single application case show that as long as the total number of distinct blocks accessed by an application is greater than the number of blocks in the buffer cache, there is a substantial difference in the response time between the DEAR and the LRU schemes. However, when the number of distinct blocks of an application is smaller than the number of blocks in the buffer cache, all the blocks are cached in the buffer cache and the two schemes show similar performance. The latter behavior is most visible for the link application that has the smallest number of distinct blocks (about 310 blocks). For link, the DEAR and the LRU schemes provide similar response times.

 

Table 3: Single application performance for various buffer cache sizes.
Application Scheme Response Time (seconds)
    2MB 4MB 6MB 8MB
cscope DEAR 16.99 14.90 12.87 11.17
  LRU 19.79 19.79 19.77 19.77
glimpse DEAR 39.12 35.68 33.73 32.87
  LRU 40.70 39.72 39.55 37.49
sort DEAR 18.16 15.54 13.60 12.10
  LRU 18.50 17.45 16.59 14.68
link DEAR 28.19 23.38 23.38 23.38
  LRU 29.65 23.35 23.35 23.35
cpp DEAR 132.94 94.42 91.61 91.36
  LRU 159.59 97.94 93.39 91.82
gnuplot DEAR 43.54 42.26 41.39 41.19
  LRU 44.30 44.30 44.30 44.30
postgres1 DEAR 38.37 36.16 34.22 32.17
  LRU 39.72 38.91 38.82 38.76
postgres2 DEAR 74.57 72.51 71.15 68.45
  LRU 82.93 74.93 74.75 73.93

 

Table 4: Multiple application performance for various buffer cache sizes.
Applications Scheme Response Time (seconds)
    4MB 6MB 8MB 10MB
cs+sort DEAR 70.4 66.6 62.9 53.5
  LRU 71.5 70.9 69.9 67.3
gli+link DEAR 79.1 74.2 71.6 70.1
  LRU 94.5 89.8 79.1 77.9
cpp+ps1 DEAR 222.2 216.7 209.8 202.4
  LRU 236.5 229.9 226.6 226.1
gli+ps2 DEAR 145.6 139.8 132.5 128.3
  LRU 165.5 155.2 146.7 138.8
cs+sort+link DEAR 116.1 112.7 106.7 101.8
  LRU 121.3 118.0 112.8 105.3
gli+sort+cpp DEAR 245.9 235.5 215.8 207.2
  LRU 246.3 245.3 225.9 222.9

 


For the multiple application case, the case where the total number of distinct blocks accessed by the component applications is smaller than the number of blocks in the buffer cache does not occur and the DEAR scheme shows consistently better performance than the LRU scheme.

 


next up previous
Next: Detection Period and the Up: Sensitivity Analysis Previous: Sensitivity Analysis

Jongmoo Choi
1999-04-22