Cache Compressor Configuration

[xfbingshan]

In gem5/src/mem/cache/compressors/Compressors.py

    dictionary_size = Param.Int(
        Parent.cache_line_size, "Number of dictionary entries"
    )

Using cache line size to set the default dictionary size may be inappropriate. For example, the original C-Pack uses 4 bits for the dictionary index, but the configuration is not rewritten.

class CPack(BaseDictionaryCompressor):
    type = "CPack"
    cxx_class = "gem5::compression::CPack"
    cxx_header = "mem/cache/compressors/cpack.hh"

    comp_chunks_per_cycle = 2
    # Accounts for pattern matching, length generation, packaging and shifting
    comp_extra_latency = 5
    decomp_chunks_per_cycle = 2
    decomp_extra_latency = 1