- Refresh user manual with up-to-date installation instructions,
and a reviewed chapter about extending the system with your own policies git-svn-id: svn://svn.gna.org/svn/sgpemv2/trunk@1065 3ecf2c5c-341e-0410-92b4-d18e462d057c
This commit is contained in:
tchernobog
parent
0c02a29f8b
commit
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@ -17,7 +17,7 @@
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This is SGPEMv2 Developer Manual (version @value{VERSION},
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@value{UPDATED}).
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Copyright @copyright{} 2005 University of Padova, dept. of Pure
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Copyright @copyright{} 2005-2006 University of Padova, dept. of Pure
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and Applied Mathematics
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Permission is granted to copy, distribute and/or modify this document
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|
|
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@ -17,7 +17,7 @@
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This is SGPEMv2 User Manual (version @value{VERSION},
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@value{UPDATED}).
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Copyright @copyright{} 2005 University of Padova, dept. of Pure
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Copyright @copyright{} 2005-2006 University of Padova, dept. of Pure
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and Applied Mathematics
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Permission is granted to copy, distribute and/or modify this document
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@ -89,6 +89,10 @@ Free Documentation License''.
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@unnumbered History
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@table @strong
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@item 2006, September 8th @r{-- Matteo Settenvini}
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Update chapters about building and installation. Rewrite some of the
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chapter about extending SGPEMv2 with custom CPU policies, and add a
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more complex example.
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@item 2006, September 7th @r{--- Luca Vezzaro}
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First attempt at expanding the manual structure with the
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stuff we'll need in the forthcoming beta testing
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@ -130,11 +134,14 @@ First draft of this document.
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@cindex description
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SGPEM is an Italian acronym, standing for ``@emph{Simulatore della Gestione dei Processi
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in un Elaboratore Multiprogrammato}'' (in English, ``@emph{Multitasking Computer Process
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Management Simulator}'').
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in un Elaboratore Multiprogrammato}'' (in English, ``@emph{Process
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Management Simulator for a Multitasking Computer}'').
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It was initially developed for use inside the ``Operating Systems'' teaching,
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part of the Computer Science course of the University of Padova, Italy.
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The aim of SGPEM is to provide an for simulating policies applied to sort processes, and for assigning resources in a multitasking computer. SGPEMv2 is a didactic software, and it can help students to understand better the functionality of Operating Systems.
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The aim of SGPEM is to provide an easy-to-use environment for
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simulating process scheduling policies, and for assigning resources in
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a multitasking computer. SGPEMv2 is an educational software, and it can
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help students to better understand the functionality of operating systems.
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@c % --------------------------------------------------
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@ -143,8 +150,8 @@ The aim of SGPEM is to provide an for simulating policies applied to sort proce
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@section How to read this manual?
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@cindex manual
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We recommend that you read the manual following the the structure that we imposed for it.
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You will be guided trough the Installation, Configuration and Usage process of SGPEM v2.
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We recommend that you read the manual following the the structure that
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we layed out for it. You will be gently led trough Installation, Configuration and Usage of SGPEMv2.
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If you find yourself in trouble reading the manual, please don't hesitate to contact us at
|
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@email{swe@@thgnet.it}.
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@ -156,7 +163,7 @@ If you find yourself in trouble reading the manual, please don't hesitate to con
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@cindex reporting
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We welcome bug reports and suggestions for any aspect of the SGPEM v2 system, program in general,
|
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documentation, installation, anything.Please email us at @email{swe@@thgnet.it}.
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documentation, installation... anything. Please email us at @email{swe@@thgnet.it}.
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For bug reporters, include enough information for us to reproduce the problem. In general:
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@itemize
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@item
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@ -193,14 +200,13 @@ You can use the program from your own shell, or if you prefer you can use the mi
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@item
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The output of the simulation is textual, and you can see it on the main GUI window or on your Terminal window.
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@item
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The policy in use if First Come First Served.
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The policy in use is First Come First Served.
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@item
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You can write your own policies.
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For more information see @ref{Writing new policies}.
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@end itemize
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@c % --------------------------------------------------
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@node Installation, Basics, Overview of SGPEM, Top
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@ -232,32 +238,22 @@ And if you find this section misses something / it lists
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the wrong version of a program, please let us know!
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@c % ---- new subsection
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@subsection Developers
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@subsection Runtime dependencies
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Other than the tools needed by users building from sources,
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you'll need:
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To run SGPEMv2, you require:
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@table @emph
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@item GCC with C++ support
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as well as the other standard GNU binutils and tools: make, sed, ld...
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GCC version >=3.4 is highly recommended. Please don't report
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compiling-related problems with any previous version.
|
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|
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@item Automake >= 1.9
|
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We use a single @file{Makefile.am} to avoid
|
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recursive make. Older versions of automake didn't play right
|
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with it. See @url{http://aegis.sourceforge.net/auug97.pdf} for
|
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the motivations that led to this choice.
|
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@item Gtkmm >= 2.8 with Cairo support
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The popular C++ jacket for the even-more popular GIMP
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ToolKit. We use Cairo to draw our custom widgets.
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@item Autoconf, libtool, autopoint @dots{}
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The standard autotool family.
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@item Python >= 2.3
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We use Python to let the user write her own policies
|
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in a simple and complete language.
|
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|
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@item Subversion >= 1.2
|
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If you need to update the sources from our repository, or commit
|
||||
your changes, you'll need Subversion built with SSL support.
|
||||
|
||||
@item Dejagnu >= 1.4
|
||||
The testsuite framework we use as a platform for running tests.
|
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@item libXML2 >= 2.6.10
|
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An XML library we use to save and load files to/from disk.
|
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|
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@end table
|
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|
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@ -275,23 +271,36 @@ Python can use, starting from a simple interface specification.
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@end table
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|
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@c % ---- new subsection
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@subsection Runtime dependencies
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@subsection Developers
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|
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To run SGPEMv2, you require:
|
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Other than the tools needed by users building from sources,
|
||||
you'll need:
|
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|
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@table @emph
|
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@item GCC with C++ support
|
||||
as well as the other standard GNU binutils and tools: make, sed, ld...
|
||||
GCC version >=3.4 is highly recommended. Please don't report
|
||||
compiling-related problems with any previous version. There are some
|
||||
known issues with certain versions of GCC 4.0. @xref{Building}.
|
||||
|
||||
@item Gtkmm >= 2.8 with Cairo support
|
||||
The popular C++ jacket for the even-more popular GIMP
|
||||
ToolKit. We use Cairo to draw our custom widgets.
|
||||
@item Automake >= 1.9
|
||||
We use a single @file{Makefile.am} to avoid
|
||||
recursive make. Older versions of automake didn't play right
|
||||
with it. See @url{http://aegis.sourceforge.net/@/auug97.pdf} for
|
||||
the motivations that led to this choice.
|
||||
|
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@item Python >= 2.3
|
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We use Python to let the user write her own policies
|
||||
in a simple and complete language.
|
||||
@item Autoconf, libtool, autopoint @dots{}
|
||||
The standard autotool family.
|
||||
|
||||
@item Subversion >= 1.2
|
||||
If you need to update the sources from our repository, or commit
|
||||
your changes, you'll need Subversion built with SSL support.
|
||||
|
||||
@item Dejagnu >= 1.4
|
||||
The testsuite framework we use as a platform for running tests.
|
||||
|
||||
@end table
|
||||
|
||||
|
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@c % --------------------------------------------------
|
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|
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@node Building, (none), Prerequisites, Installation
|
||||
|
|
@ -300,49 +309,70 @@ in a simple and complete language.
|
|||
|
||||
@noindent To ensure a clean build, follow these steps:
|
||||
|
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@sp 1
|
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@example
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@code{cd <this directory>}
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@code{cd <the package root directory>}
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||||
@code{mkdir =build}
|
||||
@code{cd =build}
|
||||
@code{CXXFLAGS="what you want" ../configure --prefix=/usr/local}
|
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@end example
|
||||
@sp 2
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@sp 1
|
||||
|
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@noindent This will check you have all the needed software installed.
|
||||
|
||||
@noindent Choosing good @env{CXXFLAGS} to optimize your build.
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@noindent Choose good @env{CXXFLAGS} to optimize your build.
|
||||
For example, on my machine, I would use:
|
||||
|
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@sp 1
|
||||
@example
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||||
@code{CXXFLAGS="-O3 -pipe -march=pentium4" ../configure --prefix=/usr/local}
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||||
@end example
|
||||
@sp 2
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||||
@sp 1
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||||
|
||||
@noindent Being a developer, though, if I had to debug SGPEM, I would type:
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||||
@noindent Being a developer, though, if I had to debug SGPEM, I would
|
||||
type:
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||||
|
||||
@sp 1
|
||||
@example
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||||
@code{CXXFLAGS="-O0 -g -ggdb -pg" ../configure \}
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@code{ --prefix=`pwd`/_inst}
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||||
@code{../configure --prefix=`pwd`/../=inst --enable-debug}
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@end example
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@sp 2
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@sp 1
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|
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@noindent Please note that those around ``pwd'' are backticks, and not
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||||
normal apostrophes.
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||||
|
||||
@strong{Warning}: at the moment, we are aware that passing
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||||
@option{--disable-shared} to configure doesn't work. We'll look into it
|
||||
sooner or later, but in the meantime just build shared libraries.
|
||||
|
||||
@noindent Once succesfully configured SGPEMv2, just type:
|
||||
|
||||
@sp 1
|
||||
@example
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||||
@command{make}
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||||
@end example
|
||||
@sp 2
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@sp 1
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||||
|
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@noindent And upon a succesful build, you can install it just by:
|
||||
@noindent Some versions of GCC 4, usually those before the 4.1 series,
|
||||
present some problems with the newly-added visibility support for DSO
|
||||
object symbols. For example, OpenSuSE 10.0 is known to have such
|
||||
issues. If you encounter problems during building and in linking stage
|
||||
about unresolved symbols in libraries, please re-run
|
||||
@command{configure} with the @option{--disable-visibility-support}
|
||||
option. You'll then have to run @command{make clean && make}.
|
||||
|
||||
|
||||
@noindent Upon a succesful build, you can install SGPEMv2 just by hitting:
|
||||
|
||||
@sp 1
|
||||
@example
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||||
@code{su -c "make install"}
|
||||
@end example
|
||||
@sp 2
|
||||
@sp 1
|
||||
|
||||
@noindent Root password will be required (of course, if you're
|
||||
installing it with a prefix placed inside your home directory,
|
||||
you won't need administrative rights, and just ``@samp{make install}''
|
||||
you won't need administrative rights, and just ``@command{make install}''
|
||||
will sufficit).
|
||||
|
||||
See the ``@file{INSTALL}'' file in this folder for an overview of other
|
||||
|
|
@ -353,10 +383,11 @@ See the ``@file{INSTALL}'' file in this folder for an overview of other
|
|||
We added Doxygen support to the project. If you've installed it,
|
||||
you can simply run @command{make apidox} from the package
|
||||
top source directory. The documentation will be outputted into
|
||||
the @samp{$@{BUILD_DIR@}/docs/API/} directory.
|
||||
the @samp{$@{BUILD_DIR@}/docs/API/} dir.
|
||||
|
||||
If you'd like to generate nicier inheritance graphs, you've just to
|
||||
install @command{dot}, part of the @emph{Graphviz} package.
|
||||
install @command{dot}, part of the @emph{Graphviz} package. If you
|
||||
didn't have it previously installed, you may need to re-run @command{configure}.
|
||||
|
||||
@c % --------------------------------------------------
|
||||
|
||||
|
|
@ -548,8 +579,6 @@ Each schedulable entity is represented by its name followed by its priority encl
|
|||
|
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@c % ------------------------------------------------
|
||||
|
||||
@c % -------------------------------------------------
|
||||
|
||||
@node Extending SGPEM, License, Using SGPEM, Top
|
||||
@chapter Extending SGPEM
|
||||
@cindex extending
|
||||
|
|
@ -561,16 +590,30 @@ Each schedulable entity is represented by its name followed by its priority encl
|
|||
|
||||
@end menu
|
||||
|
||||
@c % -------------------------------------------------
|
||||
|
||||
@node Writing new policies, Writing plugins, Extending SGPEM, Extending SGPEM
|
||||
@section Writing new policies
|
||||
@cindex writing policies
|
||||
|
||||
All policies are implemented in Python, but don't worry (be happy!). You don't have to be a Python expert to write a new policy.
|
||||
We'll explain you how to write a new policy on an simple example of FCFS policy. Now let's start, all you have to do is change the few bold-ed lines, of the following example.
|
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@sp 1
|
||||
All built-in policies are implemented in Python, but don't worry: you
|
||||
don't have to be a Python expert to write a new policy. We'll explain
|
||||
you how to write a new policy on an simple example of FCFS
|
||||
policy. Then a more complex example will follow: a Round Robin policy
|
||||
that uses pre-emption by priority.
|
||||
|
||||
Now let's get started, all you have to do to create your own policy is
|
||||
to change the few bold lines of the following example. Also remember
|
||||
that the name of the class have to be the same of the name of the file
|
||||
(minus the @code{.py} file extension, of course).
|
||||
|
||||
|
||||
|
||||
@c % --------- new subsection
|
||||
@subsection A beginner example: First Come First Served
|
||||
|
||||
@example
|
||||
01 from Policy import Policy
|
||||
01 from CPUPolicy import CPUPolicy
|
||||
02 class fcfs(Policy) :
|
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03 def __init__(self):
|
||||
04 pass;
|
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|
|
@ -586,48 +629,220 @@ We'll explain you how to write a new policy on an simple example of FCFS policy.
|
|||
|
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11 def sort_queue(self, event, queue):
|
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@strong{12 cmpf = lambda a, b: \
|
||||
a.get_schedulable().get_arrival_time() < \
|
||||
a.get_schedulable().get_arrival_time() <= \
|
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b.get_schedulable().get_arrival_time()
|
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13 self.sort(queue,cmpf)}
|
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@end example
|
||||
@sp 2
|
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|
||||
|
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@itemize
|
||||
@item body of @code{def configure(self):} line 06 - Configure policy to initial values.
|
||||
This is called just before a simulation starts, and is responsible to define
|
||||
@table @asis
|
||||
@item body of @code{def configure(self)}: line 06
|
||||
|
||||
Configure policy to initial values. This is called just before a
|
||||
simulation starts, and it is responsible to define
|
||||
the parameters the policy wants to expose to the user. For example, it may make
|
||||
the return value of is_preemptive configurable, or register an integer value for
|
||||
a the time slice duration.
|
||||
@sp 1
|
||||
@item body of @code{def is_preemptive(self):} line 08 - It says whether the policy wants to be preemptive, other than by normal time slice termination.
|
||||
the return value returned by @code{is_preemptive()} configurable, or
|
||||
to register an integer value for a the time slice duration.
|
||||
|
||||
@item body of @code{def is_preemptive(self):} line 08
|
||||
|
||||
It says whether the policy wants to be preemptive, other than by
|
||||
normal time slice termination (if a positive time slice has been provided).
|
||||
|
||||
The possible return values are:
|
||||
@enumerate
|
||||
@item True
|
||||
If the policy declares it wants the running process to be released if a process at higher priority is put at the beginning of the ready processes queue
|
||||
@enumerate
|
||||
|
||||
@item
|
||||
@code{True}: If the policy returns True, it declares that it wants the running
|
||||
thread to be released if a thread at higher priority is put at the
|
||||
beginning of the ready threads queue.
|
||||
|
||||
This is achieved by putting the current running thread, if there is
|
||||
one, onto the ready queue. It is up to you, into the
|
||||
@code{sort_queue()} method, to manage this special case.
|
||||
|
||||
@item
|
||||
@code{False}: The policy always waits the end of the time slice (or a thread
|
||||
blocking/termination) before selecting a new running thread, even if it
|
||||
has greater priority than the current one.
|
||||
|
||||
There will never be a running thread in the ready queue passed to
|
||||
@code{sort_queue()}.
|
||||
|
||||
@item False
|
||||
If the policy always waits the end of the time slice (or a process blocking/termination, of course) before selecting a new running process, even if it has greater priority than the current one.
|
||||
@end enumerate
|
||||
|
||||
Please note how the word ``priority'' here has a general meaning: it indicates every process than
|
||||
Please note how the word ``priority'' here has a general meaning: it indicates every thread than
|
||||
can bubble up the sorted ready queue and come before another. So it's up
|
||||
to Policy.sort_queue() to give it a precise meaning.
|
||||
|
||||
@sp 1
|
||||
@item body of @code{def get_time_slice(self):} line 10 - Returns how long is a time-slice for this policy.
|
||||
A time sliced policy should return a positive integer value, a policy which doesn't use slices should instead
|
||||
return -1. You're encouraged to use a user-configurable parameter via Policy.configure() if the policy is
|
||||
@item body of @code{def get_time_slice(self):} line 10
|
||||
|
||||
Returns how long is a time-slice for this policy.
|
||||
A time sliced policy should return a positive integer value, a policy
|
||||
which doesn't use slices should instead
|
||||
return @code{-1}. You're encouraged to use a user-configurable
|
||||
parameter via @code{Policy.configure()} if the policy is
|
||||
time-sliced, to ensure greater flexibility.
|
||||
|
||||
@sp 1
|
||||
@item body of
|
||||
@code{ def sort_queue(self, event, queue):}
|
||||
line 12,13 - Sort ready processes queue.
|
||||
This method is called by the scheduler at each step of the simulation to sort the ready processes queue.
|
||||
@item body of @code{ def sort_queue(self, event, queue):} line 12,13
|
||||
|
||||
@end itemize
|
||||
Sort the queue of ready threads. This method is called by the
|
||||
scheduler at each step of the simulation to sort the ready threads
|
||||
queue. It is the core of your policy: when scheduler has to select
|
||||
a new thread it will always try to take the first of the queue. If it
|
||||
cannot run for some reason (for example, it immediately blocks), the
|
||||
second is selected and so on, until the end of the queue.
|
||||
|
||||
Remember that if @code{is_preemptible()} returns True, you may have
|
||||
a running thread in the queue. See the following example for some tips
|
||||
about how to manage this case.
|
||||
|
||||
Pay attention to the fact that we used the @code{<=} relation at line @samp{12}, and
|
||||
not a simple @code{<}. This is because @code{queue.sort()} uses a
|
||||
in-place implementation of quicksort, which is stable only when
|
||||
employed with a minor-or-equal relation. Otherwise the queue would be
|
||||
sorted, but two adjacent threads that have the same value for a given
|
||||
priority would be swapped. If your policy behaves strangely, this may
|
||||
be the cause.
|
||||
|
||||
@end table
|
||||
|
||||
@c % --------- new subsection
|
||||
@subsection Exposed interface: what you can use
|
||||
|
||||
@anchor{Configuring parameters}
|
||||
@subsubsection Configuring parameters
|
||||
|
||||
TODO: list and describe all methods exposed from PolicyParameters.
|
||||
|
||||
@subsubsection Methods for manipulating the ready queue
|
||||
|
||||
TODO: list and describe all methods exposed from ReadyQueue.
|
||||
|
||||
@subsubsection Properties of schedulable entities
|
||||
|
||||
TODO: list and describe all methods exposed from Schedulable,
|
||||
Thread and Process
|
||||
|
||||
|
||||
@c % --------- new subsection
|
||||
@subsection A more complete example: Round Robin with priority
|
||||
|
||||
Now, let's see a more interesting (and a little more complex) example:
|
||||
a Round Robin by priority policy that can optionally also work with
|
||||
pre-emption by priority.
|
||||
|
||||
@sp 2
|
||||
@example
|
||||
00 from CPUPolicy import CPUPolicy
|
||||
01
|
||||
02 class rr_priority(CPUPolicy) :
|
||||
03 """Round Robin scheduling policy that takes priority in account.
|
||||
04
|
||||
05 No lower priority thread can run if a higher
|
||||
06 priority thread exists. If pre-emptive by priority, a
|
||||
07 higher-priority thread becoming ready even in the middle
|
||||
08 of a time slice will pre-empt the running thread. Else,
|
||||
09 the time slice will have to end before the former can run."""
|
||||
10
|
||||
11 def __init__(self):
|
||||
12 pass;
|
||||
13
|
||||
14 def configure(self):
|
||||
15 param = self.get_parameters()
|
||||
16 param.register_int("Time slice", 1, 10000, True, 2)
|
||||
17 param.register_int("Is preemptive?", 0, 1, True, 1)
|
||||
18
|
||||
19 def is_preemptive(self):
|
||||
20 value = self.get_parameters().get_int("Is preemptive?")
|
||||
21 if value == 0:
|
||||
22 return False
|
||||
23 else:
|
||||
24 return True
|
||||
25
|
||||
26 def get_time_slice(self):
|
||||
27 return self.get_parameters().get_int("Time slice")
|
||||
28
|
||||
29 def sort_queue(self, queue):
|
||||
30 by_ltime = lambda a, b: \
|
||||
31 a.get_last_acquisition() <= \
|
||||
32 b.get_last_acquisition()
|
||||
33 by_prio = lambda a, b: \
|
||||
34 a.get_current_priority() <= \
|
||||
35 b.get_current_priority()
|
||||
36
|
||||
37 self.sort(queue,by_ltime)
|
||||
38 self.sort(queue,by_prio)
|
||||
39
|
||||
40 # manage preemption: see if we've a running thread
|
||||
41 # in the ready queue, and if it can still run
|
||||
42 if self.is_preemptive() == True:
|
||||
43 higher_prio = queue.get_item_at(0).get_current_priority()
|
||||
44 i = 0
|
||||
45 while i < queue.size():
|
||||
46 sched = queue.get_item_at(i)
|
||||
47 priority = sched.get_current_priority()
|
||||
48 if(priority != higher_prio):
|
||||
49 break
|
||||
50 if sched.get_state() == "running":
|
||||
51 queue.bubble_to_front(i)
|
||||
52 i += 1
|
||||
@end example
|
||||
|
||||
We've also added a description of the class immediately
|
||||
following the class declaration (lines @samp{03-09}). This is what is
|
||||
returned as the policy description in the frontend. You may want to
|
||||
document your policies in the same way too.
|
||||
|
||||
Now, let's see the most complex parts together:
|
||||
|
||||
@table @code
|
||||
@item configure()
|
||||
|
||||
There are three types of parameters you can register in the value
|
||||
returned by @code{self.get_parameters()}, and they are integer
|
||||
parameters, float parameters and strings. Usually boolean values can
|
||||
be simulated by registering a integer parameter limited in the
|
||||
interval [0, 1]. @xref{Configuring parameters} for the exposed interface.
|
||||
|
||||
@item is_preemptive()
|
||||
|
||||
TODO: write me
|
||||
|
||||
@item sort_queue()
|
||||
|
||||
Here there are quite a lot of things going on, so let's tackle them
|
||||
one by one.
|
||||
|
||||
At line @samp{30} we create a lambda-function that says to sort the queue
|
||||
by last aquisition time, so that threads that have been aquired
|
||||
recently end up at the back of the queue (which is exactly what a
|
||||
Round Robin policy should do).
|
||||
|
||||
Then, at line @samp{33}, we create another lambda-function, this time
|
||||
because we want to sort the queue by priority, too.
|
||||
|
||||
Done this, we let quicksort do the hard job at lines @samp{37-38}.
|
||||
|
||||
Since we may have pre-emption enabled, we may have a running thread on
|
||||
the ready queue (if one exists at the current instant). But what
|
||||
happens if the running thread was put in the queue, and we just sorted it?
|
||||
|
||||
Unfortunately, having the greatest last aquisition time, the running thread would end
|
||||
at the back of the queue, thus never being selected to run for more
|
||||
than a single time unit if the queue is non-empty and there are other
|
||||
threads with the same priority!
|
||||
|
||||
The solution is to check if there is a thread with state ``running''
|
||||
at the beginning of the queue, between those that have the same
|
||||
priority. If there's one, we make it bubble to the top of the queue.
|
||||
|
||||
This is the explanation for lines @samp{42-52}.
|
||||
|
||||
@end table
|
||||
|
||||
|
||||
@c % -------------------------------------------------
|
||||
|
|
@ -636,6 +851,7 @@ This method is called by the scheduler at each step of the simulation to sort th
|
|||
@section Writing plugins
|
||||
@cindex plugins
|
||||
|
||||
TODO: write me
|
||||
|
||||
@c % -------------------------------------------------
|
||||
@c include license text
|
||||
|
|
|
|||
Loading…
Reference in New Issue