Cilkmem

A memory high-water mark analysis tool for Cilk-based programs.

To build

First, you will need to build LLVM with up-to-date CSI support. Please pull:

• the WIP-taskinfo branch of Tapir-LLVM (into a folder llvm);
• the WIP-csi-tapir-exceptions branch of Tapir-Clang (into llvm/tools/clang);
• the WIP-cilksan-bugfixes branch of Tapir-compiler-rti (into llvm/projects/compiler-rt).

After you've pulled the three branches, build LLVM, Clang and the CSI runtime (make clang csi should suffice). Make sure you also have the Cilk runtime (cilkrts), available here, installed in the system.

Then it's enough to run:

LLVM_BIN=/path/to/llvm/build/bin LLVM_DIR=/path/to/llvm make

assuming LLVM is built into /path/to/llvm/build and the source is in /path/to/llvm.

To run

After you've built the tool, you will have two binaries (normal and instr). These binaries are the result of compiling the Cilk program defined in test.cpp.

The normal binary is not instrumented. Running normal will run the Cilk program without anything else happening.

The instr binary is instrumented with the memory high-water mark tool. Before running instr, make sure you run the instrumented program with only one Cilk worker!. To do this:

CILK_NWORKERS=1 ./instr

Tool's options

You can use the following environmental variables to set some of the tool's options:

• MHWM_FullSPDAG=1 -> Make the tool keep more information on the SP DAG so that it can be output as a graph for easier visualization.
• MHWM_Online=1 -> Run the memory high-water mark algorithm online. If set to 0, the algorithm is run at the end of the program.
• MHWM_Efficient=1 -> Run the memory-efficient version of the algorithm.

You can also configure the memory limit you want to test the program against and the number of processors (respectively M and p, used to calculate 2M/p by the algorithm):

• MHWM_MemLimit=(value)
• MHWM_NumProcessors=(value)

Example

To run the tool offline, producing the full SP graph, using the non-efficient version of the algorithm, with M=10MiB and p=8:

MHWM_FullSPDAG=1 MHWM_Online=0 MHWM_Efficient=0 MHWM_MemLimit=10485760 MHWM_NumProcessors=8 CILK_NWORKERS=1 ./instr

To run the tool online, without producing the full graph, using the efficient version of the algorithm, with M=20KiB and p=4:

MHWM_FullSPDAG=0 MHWM_Online=1 MHWM_Efficient=1 MHWM_MemLimit=20480 MHWM_NumProcessors=4 CILK_NWORKERS=1 ./instr