Profiling tools

profiling_commands.txt

gprof

Prints a report containing time spent in each function. Also prints a report on the call graph by
telling for each function how many times was called and by whom, and also how many times it called
each other function.

1. Compile with flag -pg and optimizations.
2. Run executable, file gmon.out will be created.
3. Run $ gprof <path to binary>

NOTE: This requires some packages related to the kernel, if prompted to install something 
      in step 3, then install it and repeat everything.
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strace

Prints every system call made by a process, and can filter them. Common use case:

  $ strace -c -S time <binary>    // Count all system calls and sort them by time
  $ strace -e open <binary>       // Print all calls made to open()
  
Change <binary> to -p <PID> to attach it to a running process.

NOTE: strace outputs to stderr, to grep the output of stderr use:
  $ strace <options> 2>&1 | grep <options>
  
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perf

It's a very complex tool, at the moment I have used it to get cache misses, brach misses, 
page faults etc., the following command adds cache misses to the default event list.

  $ perf stat -e task-clock,context-switches,cpu-migrations,page-faults,cycles,instructions,\
      cache-references,cache-misses,branches,branch-misses <binary>

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BCC

On newer kernels (4.1 and above) this tool is available https://github.com/iovisor/bcc seems 
to be a powerful way to profile a process. I need to take a closer look at it.