ChampSim

ChampSim is a trace-based simulator for a microarchitecture study.

Clone ChampSim repository

git clone https://github.com/adwaitjog/ChampSim.git

Compile

ChampSim takes six parameters: Branch predictor, L1D prefetcher, L2C prefetcher, LLC_PREFETCHER, LLC replacement policy, and the number of cores. For example, ./build_champsim.sh bimodal no no lru 1 builds a single-core processor with bimodal branch predictor, no L1/L2/LLC data prefetchers, and the baseline LRU replacement policy for the LLC.

$ ./build_champsim.sh bimodal no no no lru 1

$ ./build_champsim.sh ${BRANCH} ${L1D_PREFETCHER} ${L2C_PREFETCHER} ${LLC_PREFETCHER} ${LLC_REPLACEMENT} ${NUM_CORE}

Run simulation

Execute run_champsim.sh with proper input arguments. The default TRACE_DIR in run_champsim.sh is set to $PWD/dpc3_traces.

• Single-core simulation: Run simulation with run_champsim.sh script.

Usage: ./run_champsim.sh [BINARY] [N_WARM] [N_SIM] [TRACE] [OPTION]
$ ./run_champsim.sh bimodal-no-no-no-lru-1core 1 10 400.perlbench-41B.champsimtrace.xz

${BINARY}: ChampSim binary compiled by "build_champsim.sh" (bimodal-no-no-lru-1core)
${N_WARM}: number of instructions for warmup (1 million)
${N_SIM}:  number of instructinos for detailed simulation (10 million)
${TRACE}: trace name (400.perlbench-41B.champsimtrace.xz)
${OPTION}: extra option for "-low_bandwidth" (src/main.cc)

Simulation results will be stored under "results_${N_SIM}M" as a form of "${TRACE}-${BINARY}-${OPTION}.txt".

• Multi-core simulation: Run simulation with run_4core.sh script.
  

Usage: ./run_4core.sh [BINARY] [N_WARM] [N_SIM] [N_MIX] [TRACE0] [TRACE1] [TRACE2] [TRACE3] [OPTION]
$ ./run_4core.sh bimodal-no-no-no-lru-4core 1 10 0 400.perlbench-41B.champsimtrace.xz \\
  401.bzip2-38B.champsimtrace.xz 403.gcc-17B.champsimtrace.xz 410.bwaves-945B.champsimtrace.xz

Note that we need to specify multiple trace files for run_4core.sh. N_MIX is used to represent a unique ID for mixed multi-programmed workloads.

Add your own branch predictor, data prefetchers, and replacement policy

Copy an empty template

$ cp branch/branch_predictor.cc prefetcher/mybranch.bpred
$ cp prefetcher/l1d_prefetcher.cc prefetcher/mypref.l1d_pref
$ cp prefetcher/l2c_prefetcher.cc prefetcher/mypref.l2c_pref
$ cp prefetcher/llc_prefetcher.cc prefetcher/mypref.llc_pref
$ cp replacement/llc_replacement.cc replacement/myrepl.llc_repl

Work on your algorithms with your favorite text editor

$ vim branch/mybranch.bpred
$ vim prefetcher/mypref.l1d_pref
$ vim prefetcher/mypref.l2c_pref
$ vim prefetcher/mypref.llc_pref
$ vim replacement/myrepl.llc_repl

Compile and test

$ ./build_champsim.sh mybranch mypref mypref mypref myrepl 1
$ ./run_champsim.sh mybranch-mypref-mypref-mypref-myrepl-1core 1 10 bzip2_183B

Evaluate Simulation

ChampSim measures the IPC (Instruction Per Cycle) value as a performance metric.
There are some other useful metrics printed out at the end of simulation.

Good luck and be a champion!