Axis Profile
------------

Simple utility that collects current program counter data from a
specially modified Linux kernel at a set rate and compares this to all
debug symbols in the kernel and optionally any user space programs or
libraries.

Currently, the kernel modifications (SYSTEM_PROFILER=y) exist only for
the Axis Communications CRIS ports of Linux in the mainline version of
the Linux kernel.

Written in C, but uses some external programs via system(3) (expect,
wget and one of objdump, nm, readelf).

The utility should be possible run on any operating system with these
tools installed.

Most Linux kernel architectures have support for profiling via other
means, and userspace applications uses toolchain support for profiling (gprof)
which is a more intrusive solution (toolchain support needed, profiled
code runs slower) etc.

Advantages of doing it this way is the minor changes needed in the
kernel, the light weight nature of the profiling (it doesn't cost much
to copy a PC to a circular memory buffer).

It can also give profiling info for all levels of the system at the
same time (kernel, modules, libraries, and userspace programs)

The downside is that the profiling information is not exact,
but represents an average Some code, which is triggered by the
timer interrupt used for polling the PC will never be active when
the polling occurs, and some interrupts may have higher priority.

Self modifying code or any other code that does not have any debug
symbols (such as library trampolines) will not be attributed
correctly either.

Questions and comments about axis_profile should be sent to:

axis-profile@axis.com