Cpu Profiling With Gperftools

In this post I'll go through how you can get a CPU profile for C/C++ programs using the gperftools CPU profiler an view it with pprof.

Install necessary tools

gperftools

On 64-bit systems, install libunwind, see here why.

sudo apt install libunwind-dev

Now you can install gperftools.

Download the latest release from here and unpack it.

wget https://github.com/gperftools/gperftools/releases/download/gperftools-2.9.1/gperftools-2.9.1.tar.gz
tar xf gperftools-2.9.1.tar.gz

Then configure, build and install it.

./configure --prefix=your_install_path
make -j $(nproc) install

pprof

install Go.

Install Graphviz(for graph view):

sudo apt install graphviz

Then install pprof.

go get -u github.com/google/pprof

Generate CPU profile

compile code with debug symbols

link profile lib

LD_PRELOAD=your_install_path/lib/libprofiler.so

activate CPU profiling

• by defining the CPUPROFILE environment variable

• by defining the CPUPROFILE environment variable and the the CPUPROFILESIGNAL environment variable

This allow you to trigger profiling by sending a signal to the process.

• by enclosing the code that you want to profile with ProfilerStart() and ProfilerStop().

These functions are declared in <gperftools/profiler.h>. ProfilerStart() will take the profile-filename as an argument.

Example

LD_PRELOAD=libprofiler.so CPUPROFILE=cpu.prof ./my_program

LD_PRELOAD=libprofiler.so CPUPROFILE=cpu.prof CPUPROFILESIGNAL=12 ./my_program
kill -12 my_program

Analyze CPU profile

• on the command line

  pprof my_program cpu.prof
  

• GUI in browser(view it as a graph, flame graph etc)

  pprof -http=:8080 my_program cpu.prof