This mainly holds the profile data.
Format of a profile file is:
  SECTION1
  SECTION2
  SECTION3
  ...
where SECTION is:
  ====
  TYPE
  ====
  func1
  func2
  func3
  ....
where TYPE can be: SYSCALL, LOCKCALL, EXPCALL, FREQCALL meaning system call, pthread 
libraries, expensive functions, frequent (primitive) functions.

See mysql.profile for example.

To construct a profile for a software. A typical way is to run performance testing
for the software and then use `OProfile' or `perf' to get the list of expensive
function calls. However, these calls could be either indeed expensive or because
of executed many times (i.e., frequent functions). It is recommended to put them
under EXPCALL section.

Another way is to use our static cost profiler in tools/StaticProfiler.
Example of its usage:

  Debug+Asserts/bin/staticprofiler -o mysql.profile -m 100 -n 100 mysqld.bc

It will analyze bitcode file mysqld.bc (compiled from clang) and output 
the top 100 expensive and top 100 frequent functions to mysql.profile.