Brussels / 31 January & 1 February 2015



The Ignominous Profiler

IgProf is a GPL, general purpose, cross platform (x86_64, x86, ARMv7-A, ARM64/AArch64), memory and performance profiling tool originally developed 10 years ago in the context of LHC experiments at CERN (*), to enable optimisation of simulation and data acquisition software. It provides detailed, call-stack level, information on where time / energy is spent and memory allocations happen using a variety of techniques varying from dynamic instrumentation to sampled profiling. While not dissimilar from other similar softwares like Google perftools it was specially tailored to profile extremely large C++ applications comprising millions lines of codes, loading thousands of dynamic libraries and with a very high memory allocation frequency. In addition, ease-of-use and the ability to easily share performance profiles between distributed collaborators are important aspects to enable use by a large community of scientists with varying software development skills.

We present our experience about profiling and improving performance of large applications, discuss similarities and differences with other similar tools and show a few of the new features we have been working on lately, in particular ARM64 support and energy profiling via a PAPI add on. We also show how we gave back to the opensource community by providing patches to libunwind for both x86 and ARM.

(*) CMS is one of the flagship experiments at CERN, a collaboration of over 4000 researchers distributed in more than 100 institutes around the world. They use a distributed computing architecture consisting of more than 100K x86-64 cores to answer questions about the origin of the universe and the structure of matter. Given the scale of the computational resources, software performance optimization is a critical need.


Giulio Eulisse