Prj1README.txt

GENRAL:
    - Sample runs are provided in "Problem X/log"
    - All binaries are build in "bin/"
    - StopWatch (problem 4) and ForkCopy (problem 2) must be runned in "bin/" directory!
    - Documentation for each program is provied in Documentation.pdf



SUBMITTED FILES:
    - makefile                  | makefile building all binaries to bin/
    - Prj1README.txt            | readme file
    - Documentation.pdf         | small documentation for all problems
    - log.txt                   | log file containing runs of all programs
    - Problem 1                 | 
        - MyCopy.c              | implementation of problem 1
    - Problem 2                 | 
        - ForkCopy.c            | implementation of problem 2
    - Problem 3                 | 
        - PipeCopy.c            | implementation of problem 3
    - Problem 4                 | 
        - StopWatch.c           | programm calling all copy programs to test their performance (see notes below!)
    - Problem 5                 | 
        - MyShell.h             | implementation of problem 5 (header file)
        - MyShell.c             | implementation of problem 5
    - Problem 6                 | 
        - MoreShell.h           | implementation of problem 6 (header file)
        - MoreShell.c           | implementation of problem 6
    - Problem 7                 | 
        - DupShell.h            | implementation of problem 7 (header file)
        - DupShell.c            | implementation of problem 7
    - Problem 8                 | 
        - MergesortSignle.c     | implementation of problem 8 (single threaded)
        - MergesortMulti.c      | implementation of problem 8 (multi threaded)
    - Problem 9                 | 
        - BurgerBuddies.c       | implementation of problem 9



NOTES PROBLEM 4:
    In order to measure the execution times of MyCopy, ForkCopy and PipeCopy a new program
    called StopWatch was implemented. StopWatch forks a child and executes the copy programs
    in it. The time the child needs to complete is measured. 
    Because clock() estimates the CPU time needed by the process the result for the measurment
    with clock() is always zero. The parent process is in blocked state after calling wait() 
    and therefor needs no CPU time. Additionally, the return value of clock() is incremented in
    10^4 steps and CLOCKS_PER_SEC is 10^6 on POSIX compliant systems. This leeds to a poor
    precision of 10ms using clock().

    The result of the measurements are shown in the following table:
    ============================================================================
    | Program        | clock()   | gettimeofday()        | clock_gettime()     |
    ----------------------------------------------------------------------------
    | cp             | 0.000ms   | 157.469970703125ms    | 157.468261718750ms  |
    | ./MyCopy       | 0.000ms   | 783.482910156250ms    | 783.483398437500ms  |
    | ./ForkCopy     | 0.000ms   | 779.437011718750ms    | 779.438232421875ms  |
    | ./PipeCopy     | 0.000ms   | 2515.257812500000ms   | 2515.258789062500ms |
    ============================================================================



TEST ENVIRONMENT:
    - Ubuntu 13.04
    - GCC version information (gcc -v):
        Using built-in specs.
        COLLECT_GCC=gcc
        COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
        Target: x86_64-linux-gnu
        Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.7.3-1ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --with-system-zlib --enable-objc-gc --with-cloog --enable-cloog-backend=ppl --disable-cloog-version-check --disable-ppl-version-check --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
        Thread model: posix
        gcc version 4.7.3 (Ubuntu/Linaro 4.7.3-1ubuntu1)