mpi-clock-sync

This repository contains the mpits library, which can be used to synchronize the clocks of distributed MPI processes.

This is a software solution based on MPI.

Building mpits

mkdir build
cd build
cmake ..
make -j

You may also choose a target directory for the library, e.g.,

mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=$HOME/local/mpits ..
make -j
make install

Selecting a Clock Synchronization Algorithm

The following clock synchronization algorithms are available:

• HCA, $O(\log p)$ for linear model for the clock drift, $O(p)$ for the clock offset
• HCA2, $O(\log p)$, linear model for the clock drift and clock offset
• HCA3, $O(\log p)$, linear model for the clock drift and clock offset
• HCA3O, $O(\log p)$, fast, only computes clock offset
• JK, $O(p)$ to compute drift and offset
• SKAMPI, $O(p)$ for clock offset computation (no clock drift)
• TOPO1, meta algorithm, determines hierarchy via hwloc
  • 3 levels, inter-node, node-level, socket-level
• TOPO2, meta two-level algorithm, MPI-only
  • 2 levels, inter-node, node-level
  • one can apply different algorithms to each level
• NONE, no clock synchronization
  • used for passing time through (for time synchronized systems, e.g., PTP, BlueGen/Q, etc.)

export MPITS_PARAMS="--clock-sync=HCA3O --params=alg:HCA3O@skampi_offset@5@20"

Support for hwloc

-DHWLOC_LIBRARY_DEFAULT_PATH=PATH_TO_HWLOC