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How the Profile Clock gets clock counts?

challenger002
Intellectual 690 points

I want to find out how the Profile Clock gets clock counts because I have the problem as I described it in the following link.

http://e2e.ti.com/support/development_tools/code_composer_studio/f/81/t/158874.aspx

I saw the Compiler User's Guide for C55x.

TMS320C55x Optimizing C/C++ Compiler User's Guide (Rev. G)
http://www.ti.com/lit/ug/spru281g/spru281g.pdf
2.3.5 Symbolic Debugging and Profiling Options
3.8.2 Profiling Optimized Code

The document has the description about the profiler that is two kinds of "breakpoint-based profiler" and "power-profiler" and that disturbs the optimization.
But I was not able to find out what the profiler does for the code that is not optimized or that was written with the assembler directly.

What are "breakpoint-based profiler" and "power-profiler" each?

How the Profile Clock gets clock counts?
Is the timer used?

Best regards,
Daisuke

 

  • 0
    TI__Guru**** 161575 points

    Daisuke,

    The breakpoint based profiler is a function profiler in CCS that sets breakpoints on each branch in the region of code being profiled.  This enables it to track execution flow and assign the cycles executed to the appropriate function.  When you are using the function profiler on C55x it is using the breakpoint profiler.  In order to be able to set breakpoints on branches, function entry/exit it is necessary for there to be symbolic debug information present.

    As far as getting the cycle count this is done by reading the CLK register.

    On some targets we can use trace information to do profiling which is non-intrusive.

    http://processors.wiki.ti.com/index.php/Profiler

    http://processors.wiki.ti.com/index.php/Profile_clock_in_CCS

    The power profiler is no longer supported.  This used instrumentation to estimate power consumption on C55x.

    Regards,

    John

  • 0 in reply to JohnS
    Intellectual 690 points

    Thank you for a reply.

    I was thought the profile clock is a part of the profiler (the function profiler) and is the method same as it.

    But I understood that for counting instruction cycles the profile clock is exact and the profiler is not exact.

    Is my understanding right?

    Best regards,

    Daisuke

  • 0 in reply to challenger002
    TI__Guru**** 161575 points

    The breakpoint based function profiler makes use of the profile clock.  It uses the profile clock to count cycles between the breakpoints.

    The breakpoint based function profiler is constantly halting the application which can change the behavior of the system.  i.e. interrupts can get missed.  Thus it is not a good way to measure overall performance.  Using the profile clock to measure cycles between 2 points is much less intrusive.

  • 0 in reply to JohnS
    Intellectual 690 points

    Thank you for a reply.

    I understood that the profiler can precisely count cycles by taking care of only that breakpoints halt the application.

    Best regards,

    Diasuke