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Profiling

Profiling. Chihao Li , Department of Mathematics, National Taiwan University 2011/7/7. What is Profiling?. A good program need?. Accuracy? Effeciency ? Readability? Rewritability ? Easy to debug?. When to Profile?. Time to use is “using time”!.

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Profiling

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  1. Profiling Chihao Li, Department of Mathematics, National Taiwan University2011/7/7

  2. What is Profiling? Profiling

  3. A good program need? • Accuracy? • Effeciency? • Readability? • Rewritability? • Easy to debug? Profiling

  4. When to Profile? Profiling

  5. Time to use is “using time”! • To evaluate the difference of executing time. • Decide which step costs the most time. • Goal: improve the efficiency. Profiling

  6. Memory control and Debugging Profiling

  7. prof/gprof: Execution Profiling • Generate information of the detailed executing time on each function. • Use flags: -p/-pgfor prof/gprof. • $ gcc-pg *.c • $ time ./a.out • $ gprofa.outgmon.out -bp Profiling

  8. Assertion • Instead of using printffor debugging, we can use the macro assert: Profiling

  9. Assertion (conti.) • gcc -o assert assert.c -lm • ./assert Profiling

  10. Memory leak & Electric Fence • Memory leak: once you mallocthe memory but forget to free it, it is hard to debug but it is very important to find out. • Eletric Fence by Bruce Perens is a useful tool. Profiling

  11. Electric Fence Profiling

  12. Electric Fence (conti.) • $ gcc-o efenceefence.c • $ ./efence • $ gcc -o efenceefence.c -lefence • $ ./efence • $ gcc -g -o efenceefence.c -lefence Profiling

  13. valgrind • valgrind is another tool, you don’t need to recompile the code while using it. Profiling

  14. vargrind (conti.) Profiling

  15. valgrind (conti.) • $ valgrind --leak-check=yes -v ./checker Profiling

  16. Demo Profiling

  17. How to Profile in MATLAB? Profiling

  18. Outline • tic & toc • clock • etime • profile Profiling

  19. tic & toc • tic: Start a stopwatch timer. • toc: Read the stopwatch timer. • ticand tocfunction work together to measure elapsed time between the two. • Sample: Profiling

  20. clock • Returns current date and time as a vector. • The vector is in a decimal form containing 6 elements: • [year, month, day, hour, minute, second] • Sample: Profiling

  21. etime • etime(t1, t0)returns the time in seconds that has elapsed between vectors t1andt0. • t0andt1must be the format returned by clock. • Sample: Profiling

  22. profile • Returnssummaryoffunction calls and total time. Profiling

  23. profile - GUI • As an alternative to the profile function, • Select Desktop > Profiler to open the Profiler. • Click the “Profiler” button. • do not include “.m” in the “Run this code” field. Profiling

  24. Demo Profiling

  25. Reference • http://blogs.mathworks.com/videos/2006/10/19/profiler-to-find-code-bottlenecks/ • 鳥哥的Linux私房菜http://linux.vbird.org/ • http://www.cprogramming.com/debugging/valgrind.html • http://catchtest.pixnet.net/blog/post/22080405 • http://nixchun.pixnet.net/blog/post/12331954 Profiling

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