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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: Detection Period and the Up:
Sensitivity Analysis Previous: Sensitivity Analysis
Jongmoo Choi
1999-04-22