Cache misses in small, limited-associativityprimary caches very often replace live cache blocks, giventhe dominance of capacity and conflict misses. Towardsmotivating novel cache organizations, we study thecomparative characteristics of the virtual memoryaddress pairs involved in typical primary-cachecontention (block replacements) for the SPEC2000integer benchmarks. We focus on the cache tag bits, andresults show that (i) often just a few tag bits differbetween contending addresses, and (ii) accesses to certainsegments or page groups of the virtual address space (i.e.certain tag-bit groups) contend frequently. Cacheconsciousvirtual address space allocation can furtherreduce the number of conflicting tag bits. We mentiontwo directions for exploiting such page-level contentionpatterns to improve cache cost and performance.