A more interesting experiment concerns the comparison of different
replacement algorithms. The first question to be answered is whether a
simple replacement algorithm, like RANDOM, is good enough. RANDOM
corresponds to the simple idea of replacing any user who has been idle
for more than 
seconds. The point of reference for the comparison
is the LRU algorithm--a common benchmark in replacement problems. LRU
replaces the user who has been idle the longest (as long as this is
more than seconds, in our case). The LRU algorithm has been used
in replacement settings ranging widely (e.g., from virtual memory to
web caching [ASA 
95]). The next step is to see whether a
specialized algorithm can perform better than LRU. As we will see, the
CIRG algorithm meets this test.