sgpemv2/doc/sgpem2uman.texi

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\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename sgpem2uman.info
@settitle SGPEMv2 User Manual
@include vers-uman.texi
@c %**end of header
@dircategory SGPEM v2 - A Process Scheduling Simulator
@direntry
* Users: (sgpem2uman)Top
@end direntry
@c % --------------------------------------------------
@copying
This is SGPEMv2 User Manual (version @value{VERSION},
@value{UPDATED}).
Copyright @copyright{} 2005-2006 University of Padova, dept. of Pure
and Applied Mathematics
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
@end copying
@c % --------------------------------------------------
@titlepage
@title SGPEMv2 User Manual
@subtitle for version @value{VERSION}, @value{UPDATED}
@author Filippo Paparella (@email{ironpipp@@gmail.com})
@author Paolo Santi (@email{psanti@@studenti.math.unipd.it})
@author Matteo Settenvini (@email{matteo@@member.fsf.org})
@author Marco Trevisan (@email{evenjn@@gmail.com})
@author Djina Verbanac (@email{betalgez@@yahoo.com})
@author Luca Vezzaro (@email{lvezzaro@@studenti.math.unipd.it})
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage
@c Output the table of contents at the beginning.
@contents
@c % --------------------------------------------------
@c SGPEMv2 User Manual
@c % --------------------------------------------------
@ifnottex
@node Top, History, (none), (dir)
@top Learn how to operate SGPEMv2
@insertcopying
@end ifnottex
@menu
* History:: The history of changes to this document.
* Overview of SGPEM:: Description and objectives of SGPEM v2.
* Installation:: Here we explain how to install SGPEM v2,
as well as providing some advice for
believed-to-be useful compilation options.
* Basics:: Things you should know before starting.
* Using SGPEM:: Instructions on how to use SGPEM.
* Extending SGPEM:: Learn how to write new policies and plugins.
* License:: A full copy of the GNU Free Documentation License
this manual is licensed into.
* Concept index:: Complete index.
@end menu
@c % --------------------------------------------------
@node History, Overview of SGPEM, Top, Top
@unnumbered History
@table @strong
@item 2006, September 8th @r{-- Matteo Settenvini}
Update chapters about building and installation. Rewrite some of the
chapter about extending SGPEMv2 with custom CPU policies, and add a
more complex example.
@item 2006, September 7th @r{--- Luca Vezzaro}
First attempt at expanding the manual structure with the
stuff we'll need in the forthcoming beta testing
@item 2006, March 10th @r{--- Djina Verbanac}
Added chapter Writing new policies
@item 2006, March 9th @r{--- Djina Verbanac}
Add chapters Overview of SGPEM and Starting with SGPEM.
@item 2006, January 26th @r{--- Matteo Settenvini}
Add subsection about how to generate code documentation
via Doxygen.
@item 2005, December 11th @r{--- Matteo Settenvini}
Added full license text.
@item 2005, November 8th @r{--- Matteo Settenvini}
First draft of this document.
@end table
@c % --------------------------------------------------
@node Overview of SGPEM, Installation, History, Top
@chapter Overview of SGPEM
@menu
* Description and aims::
* How to read this manual?::
* Reporting Bugs::
* Features::
@end menu
@c % --------------------------------------------------
@node Description and aims, How to read this manual?, Overview of SGPEM, Overview of SGPEM
@section Description and aims
@cindex SGPEM
@cindex description
SGPEM is an Italian acronym, standing for ``@emph{Simulatore della Gestione dei Processi
in un Elaboratore Multiprogrammato}'' (in English, ``@emph{Process
Management Simulator for a Multitasking Computer}'').
It was initially developed for use inside the ``Operating Systems'' teaching,
part of the Computer Science course of the University of Padova, Italy.
The aim of SGPEM is to provide an easy-to-use environment for
simulating process scheduling policies, and for assigning resources in
a multitasking computer. SGPEMv2 is an educational software, and it can
help students to better understand the functionality of operating systems.
@c % --------------------------------------------------
@node How to read this manual?, Reporting Bugs, Description and aims, Overview of SGPEM
@section How to read this manual?
@cindex manual
We recommend that you read the manual following the the structure that
we layed out for it. You will be gently led trough Installation, Configuration and Usage of SGPEMv2.
If you find yourself in trouble reading the manual, please don't hesitate to contact us at
@email{swe@@thgnet.it}.
@c % --------------------------------------------------
@node Reporting Bugs,Features, How to read this manual?, Overview of SGPEM
@section Reporting Bugs
@cindex bugs
@cindex reporting
We welcome bug reports and suggestions for any aspect of the SGPEM v2 system, program in general,
documentation, installation... anything. Please email us at @email{swe@@thgnet.it}.
For bug reporters, include enough information for us to reproduce the problem. In general:
@itemize
@item
version and number of SGPEM v2.
@item
hardware and operating system name and version.
@item
the content of any file neccesary to reproduce the bug.
@item
description of the problem and any erroneous output.
@item
any unusual option you gave to configure.
@item
anything else you think might be helpful.
@end itemize
If you are ambitious you can try to fix the problem yourself, but we warmly recommend that you read the
Developer Manual first.
@c % --------------------------------------------------
@node Features, (none), Reporting Bugs, Overview of SGPEM
@section Features
@cindex features
Main features are:
@itemize
@item
For now you can use only prompt commands to start the simulation and change some parameters.
For more information see @ref{SGPEM Commands}.
@item
You can use the program from your own shell, or if you prefer you can use the minimal GUI that SGPEM offers, at this moment.
@item
The output of the simulation is textual, and you can see it on the main GUI window or on your Terminal window.
@item
The policy in use is First Come First Served.
@item
You can write your own policies.
For more information see @ref{Writing new policies}.
@end itemize
@c % --------------------------------------------------
@node Installation, Basics, Overview of SGPEM, Top
@chapter Installation
@cindex installation
@menu
* Prerequisites:: Programs and libraries needed to
compile and run SGPEM
* Building:: Help for compiling SGPEM on
your platform.
@end menu
@c % --------------------------------------------------
@node Prerequisites, Building, Installation, Installation
@section Prerequisites
@cindex requirements
Some software is needed in order to build and install SGPEM on your
personal computer. You will have the need of different pieces of
software installed, whether you are a developer, a user building it
from sources, or just a user that's running the binary a packager
has given to him.
And if you find this section misses something / it lists
the wrong version of a program, please let us know!
@c % ---- new subsection
@subsection Runtime dependencies
To run SGPEMv2, you require:
@table @emph
@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 Python >= 2.3
We use Python to let the user write her own policies
in a simple and complete language.
@item libXML2 >= 2.6.10
An XML library we use to save and load files to/from disk.
@end table
@c % ---- new subsection
@subsection Building from source
Other than the runtime dependencies, you'll need:
@table @emph
@item SWIG >= 1.3.21
SWIG generates the C++ sources needed to build a module that
Python can use, starting from a simple interface specification.
@end table
@c % ---- new subsection
@subsection Developers
Other than the tools needed by users building from sources,
you'll need:
@table @emph
@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 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.
@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
@c % --------------------------------------------------
@node Building, (none), Prerequisites, Installation
@section Building
@cindex compiling
@noindent To ensure a clean build, follow these steps:
@sp 1
@example
@code{cd <the package root directory>}
@code{mkdir =build}
@code{cd =build}
@code{CXXFLAGS="what you want" ../configure --prefix=/usr/local}
@end example
@sp 1
@noindent This will check you have all the needed software installed.
@noindent Choose good @env{CXXFLAGS} to optimize your build.
For example, on my machine, I would use:
@sp 1
@example
@code{CXXFLAGS="-O3 -pipe -march=pentium4" ../configure --prefix=/usr/local}
@end example
@sp 1
@noindent Being a developer, though, if I had to debug SGPEM, I would
type:
@sp 1
@example
@code{../configure --prefix=`pwd`/../=inst --enable-debug}
@end example
@sp 1
@noindent Please note that those around ``pwd'' are backticks, and not
normal apostrophes.
@strong{Warning}: at the moment, we are aware that passing
@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
@command{make}
@end example
@sp 1
@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
@code{su -c "make install"}
@end example
@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 ``@command{make install}''
will sufficit).
See the ``@file{INSTALL}'' file in this folder for an overview of other
(less common) autoconf options.
@subsection Generating API documentation
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/} dir.
If you'd like to generate nicier inheritance graphs, you've just to
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 % --------------------------------------------------
@node Basics, Using SGPEM, Installation, Top
@chapter Basics
@cindex basics
@menu
* Policies:: Everything you'll ever wanted to know about policies
in SGPEM!
* The Scheduler:: Essential background information necessary to
understand how schedulable entities are scheduled.
@end menu
@c % -------------------------------------------------
@node Policies, The Scheduler, Basics, Basics
@section Policies
@cindex policies
@menu
* What is a policy in SGPEM?:: Explains what a SGPEM policy can, should and must do,
and what it can't do. And how.
* What kind of policies are there?:: In SGPEM there a two very different
kinds of policies. This subsection explains
these differences.
* Built-in policies:: Here you will find a detailed descriptions of the policies
shipped with the standard distribution of SGPEM.
@end menu
@node What is a policy in SGPEM?, What kind of policies are there?, Policies, Policies
@subsection What is a policy in SGPEM?
@cindex policies basics
@node What kind of policies are there?, Built-in policies, What is a policy in SGPEM?, Policies
@subsection What kind of policies are there?
@cindex policies kinds
@node Built-in policies, (none), What kind of policies are there?, Policies
@subsection Built-in policies
@cindex built-in policies
@c % -------------------------------------------------
@node The Scheduler, (none), Policies, Basics
@section The Scheduler
@cindex scheduler basics
@c % --------------------------------------------------
@node Using SGPEM, Extending SGPEM, Basics, Top
@chapter Using SGPEM
@cindex using
@menu
* From the GUI::
* From the commandline::
@end menu
@c % -------------------------------------------------
@node From the GUI, From the commandline, Using SGPEM, Using SGPEM
@section From the GUI
@cindex GUI
@menu
* Overall view of the main window::
* The Schedulables/Requests tree::
* The Resources list::
* The Simulation widget::
* The Holt graph::
* The Preferences dialog::
* Controlling the simulation:: This subsection will explain you all the means
available to control the simulation workflow.
@end menu
@c % -------------------------------------------------
@node Overall view of the main window, The Schedulables/Requests tree, From the GUI, From the GUI
@subsection Overall view of the main window
@cindex main window
@image{main-window,18cm,13.5cm,Screenshot of the main window during a simulation}
Blah blah blah...
@c % -------------------------------------------------
@node The Schedulables/Requests tree, The Resources list, Overall view of the main window, From the GUI
@subsection The Schedulables/Requests tree
@cindex schedulables tree
@c % -------------------------------------------------
@node The Resources list, The Simulation widget, The Schedulables/Requests tree, From the GUI
@subsection The Resources list
@cindex resources
@c % -------------------------------------------------
@node The Simulation widget, The Holt graph, The Resources list, From the GUI
@subsection The Simulation widget
@cindex simulation widget
@c % -------------------------------------------------
@node The Holt graph, The Preferences dialog, The Simulation widget, From the GUI
@subsection The Holt graph
@cindex holt
@c % -------------------------------------------------
@node The Preferences dialog, Controlling the simulation, The Holt graph, From the GUI
@subsection The Preferences dialog
@cindex preferences
@c % -------------------------------------------------
@node Controlling the simulation, (none), The Preferences dialog, From the GUI
@subsection Controlling the simulation
@cindex simulation
@c % -------------------------------------------------
@node From the commandline, (none), From the GUI, Using SGPEM
@section From the commandline
@cindex commandline
@menu
* SGPEM Commands:: Here you'll find a set of commands available
from the command line
* SGPEM Output:: Interpretation of the output
@end menu
@c % -------------------------------------------------
@node SGPEM Commands, SGPEM Output, From the commandline, From the commandline
@subsection SGPEM Commands
@cindex commands
@table @strong
@item help @command{<string>}
If <string> is a valid command, it prints the usage instructions for that specific command
@item @command{run}
Advances the simulation by one or more steps, depending on the actual state and on the value set ed with setmode
@item @command{pause}
It is useful only when the advancement mode is continue. Calling again run will cause the simulation to start from the current simulation step.
@item @command{stop}
Stops the simulation.
@item @command{setmode <bool>}
This methods allows to change the way the simulation progresses. If the input value is 0 (false), the simulation will advance a single time step for each call to run. If the
input value is 1 (true), the simulation will advance contiuosly, waiting the time defined with settimer between each step, until all processes terminate,
or some error occurs.
@item @command{getmode}
Prints the simulation advancement mode: 0 if step-to-step, 1 if continue.
@item @command{settimer <int>}
This command is used to define how a single time unit is to be interpreted when the simulation advancement mode is continue.
The input value is in milliseconds, and it must be in range [0, 10000].
@item @command{gettimer}
Prints the value of the current timer
@item @command{reset}
Resets the simulation.Erases the state of the simulation, and takes care of removing any residual or temporary data to ensure the simulation has reached
a clean and stable state.
@item @command{jumpto <int>}
Causes the simulation to jump to a given time unit.
@item @command{getpolicy}
Prints the current policy.
@item @command{getpolicyattributes}
Prints the name and the value of the policy's attributes
@end table
@c % -------------------------------------------------
@node SGPEM Output, (none), SGPEM Commands, From the commandline
@subsection SGPEM Output
@cindex output
You can see the textual output of the simulation in your console window or on the GUI window provided with SGPEM v2.
The output of RUN gives you one or more rows, each one representing the state of schedulable entities.
The possible states are: @emph{RUNNING}, @emph{READY}, @emph{BLOCKED}, @emph{FUTURE} or @emph{TERMINATED}.
The row begins with the number of the instant described by the following lists of states:
@itemize
@item instant 0 - represents the INITIAL STATE during which no process is running.
@item instant 1 - the scheduler activity begins.
@end itemize
Each schedulable entity is represented by its name followed by its priority enclosed between round parenthesis.
@c % ------------------------------------------------
@node Extending SGPEM, License, Using SGPEM, Top
@chapter Extending SGPEM
@cindex extending
@menu
* Writing new policies:: Steps that must be followed to insert a new policy
* Writing plugins::
@end menu
@c % -------------------------------------------------
@node Writing new policies, Writing plugins, Extending SGPEM, Extending SGPEM
@section Writing new policies
@cindex writing policies
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 CPUPolicy import CPUPolicy
02 class fcfs(Policy) :
03 def __init__(self):
04 pass;
05 def configure(self):
@strong{06 print 'No options to configure for fcfs'}
07 def is_preemptive(self):
@strong{08 return False}
09 def get_time_slice(self):
@strong{10 return -1}
11 def sort_queue(self, event, queue):
@strong{12 cmpf = lambda a, b: \
a.get_schedulable().get_arrival_time() <= \
b.get_schedulable().get_arrival_time()
13 self.sort(queue,cmpf)}
@end example
@sp 2
@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 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
@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()}.
@end enumerate
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 @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 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 % -------------------------------------------------
@node Writing plugins, (none), Writing new policies, Extending SGPEM
@section Writing plugins
@cindex plugins
TODO: write me
@c % -------------------------------------------------
@c include license text
@node License, Concept index, Extending SGPEM, Top
@include fdl.texi
@c % --------------------------------------------------
@node Concept index, (none), License, Top
@unnumbered Index
@printindex cp
@bye