# TAG: cache_replacement_policy
# The cache replacement policy parameter determines which
# objects are evicted (replaced) when disk space is needed.
#
# lru : Squid's original list based LRU policy
# heap GDSF : Greedy-Dual Size Frequency
# heap LFUDA: Least Frequently Used with Dynamic Aging
# heap LRU : LRU policy implemented using a heap
#
# Applies to any cache_dir lines listed below this.
#
# The LRU policies keeps recently referenced objects.
#
# The heap GDSF policy optimizes object hit rate by keeping smaller
# popular objects in cache so it has a better chance of getting a
# hit. It achieves a lower byte hit rate than LFUDA though since
# it evicts larger (possibly popular) objects.
#
# The heap LFUDA policy keeps popular objects in cache regardless of
# their size and thus optimizes byte hit rate at the expense of
# hit rate since one large, popular object will prevent many
# smaller, slightly less popular objects from being cached.
#
# Both policies utilize a dynamic aging mechanism that prevents
# cache pollution that can otherwise occur with frequency-based
# replacement policies.
#
# NOTE: if using the LFUDA replacement policy you should increase
# the value of maximum_object_size above its default of 4096 KB to
# to maximize the potential byte hit rate improvement of LFUDA.
#
# For more information about the GDSF and LFUDA cache replacement
# policies see
http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
# and
http://fog.hpl.external.hp.com/techr...PL-98-173.html.