-/*! \page FAQ Frequently Asked Questions
+/*! @page FAQ MSG Frequently Asked Questions
@tableofcontents
-\section faq_simgrid I'm new to SimGrid. I have some questions. Where should I start?
+This document is the FAQ of the MSG interface. Some entries are a bit aging and it should be refreshed at some point.
-You are at the right place... Having a look to these
-<a href="http://www.loria.fr/~quinson/blog/2010/06/28/Tutorial_at_HPCS/">the slides of the HPCS'10 tutorial</a>
-(or to these <a href="http://graal.ens-lyon.fr/~alegrand/articles/slides_g5k_simul.pdf">ancient
-slides</a>, or to these
-<a href="http://graal.ens-lyon.fr/~alegrand/articles/Simgrid-Introduction.pdf">"obsolete" slides</a>)
-may give you some insights on what SimGrid can help you to do and what
-are its limitations. Then you definitely should read the \ref
-MSG_examples.
+@section faq_simgrid I'm new to SimGrid. I have some questions. Where should I start?
+
+You are at the right place... To understand what you can do or
+cannot do with SimGrid, you should read the
+<a href="http://simgrid.gforge.inria.fr/tutorials.php">tutorial
+slides</a> from the SimGrid's website. You may find more uptodate
+material on the
+<a href="http://people.irisa.fr/Martin.Quinson/blog/SimGrid/">blog of
+Martin Quinson</a>.
+
+Another great source of inspiration can be found in the @ref s4u_examples.
If you are stuck at any point and if this FAQ cannot help you, please drop us a
mail to the user mailing list: <simgrid-user@lists.gforge.inria.fr>.
-\subsection faq_interfaces What is the difference between MSG and SimDag? Do they serve the same purpose?
+@subsection faq_interfaces What is the difference between MSG and SimDag? Do they serve the same purpose?
It depend on how you define "purpose", I guess ;)
processes, exchanging data by the way of messages and performing
computation on their own.
-\subsection faq_visualization Visualizing and analyzing the results
+@subsection faq_visualization Visualizing and analyzing the results
It is sometime convenient to "see" how the agents are behaving. If you
like colors, you can use <tt>tools/MSG_visualization/colorize.pl </tt>
as a filter to your MSG outputs. It works directly with INFO. Beware,
INFO() prints on stderr. Do not forget to redirect if you want to
filter (e.g. with bash):
-\verbatim
+@verbatim
./msg_test small_platform.xml small_deployment.xml 2>&1 | ../../tools/MSG_visualization/colorize.pl
-\endverbatim
+@endverbatim
-We also have a more graphical output. Have a look at section \ref options_tracing.
+We also have a more graphical output. Have a look at section @ref options_tracing.
-\subsection faq_C Argh! Do I really have to code in C?
+@subsection faq_C Argh! Do I really have to code in C?
-Currently bindings on top of MSG are supported for Java, Ruby and Lua. You can find a few
-documentation about them on the doc page. Note that bindings are released separately from the main dist
-and so have their own version numbers.
+We provide Java bindings of the MSG interface, which is the main
+SimGrid user API.
-Moreover If you use C++,
-you should be able to use the SimGrid library as a standard C library
-and everything should work fine (simply <i>link</i> against this
-library; recompiling SimGrid with a C++ compiler won't work and it
-wouldn't help if you could).
+Moreover If you use C++, you should be able to use the SimGrid library
+as a standard C library and everything should work fine (simply
+<i>link</i> against this library; recompiling SimGrid with a C++
+compiler won't work and it wouldn't help if you could).
-For now,
-we do not feel a real demand for any other language. But if you think there is one,
- please speak up!
+For now, we do not feel a real demand for any other language. But if
+you think there is one, please speak up!
-\section faq_howto Feature related questions
+@section faq_howto Feature related questions
-\subsection faq_MIA "Could you please add (your favorite feature here) to SimGrid?"
+@subsection faq_MIA "Could you please add (your favorite feature here) to SimGrid?"
Here is the deal. The whole SimGrid project (MSG, SURF, ...) is
meant to be kept as simple and generic as possible. We cannot add
people have asked about it and we have given hints on how to simply do
it with MSG. Feel free to contribute...
-\subsection faq_MIA_MSG MSG features
+@subsection faq_MIA_MSG MSG features
-\subsubsection faq_MIA_examples I want some more complex MSG examples!
+@subsubsection faq_MIA_examples I want some more complex MSG examples!
Many people have come to ask me a more complex example and each time,
they have realized afterward that the basics were in the previous three
us if something is not clear and once again feel free to participate!
:)
-\subsubsection faq_MIA_taskdup Missing in action: MSG Task duplication/replication
+@subsubsection faq_MIA_taskdup Missing in action: MSG Task duplication/replication
There is no task duplication in MSG. When you create a task, you can
process it or send it somewhere else. As soon as a process has sent
You could use a dictionary (#xbt_dict_t) of dynars (#xbt_dynar_t). If
you still don't see how to do it, please come back to us...
-\subsubsection faq_MIA_asynchronous I want to do asynchronous communications in MSG
-
-In the past (version <= 3.4), there was no function to perform asynchronous communications.
-It could easily be implemented by creating new process when needed though. Since version 3.5,
-we have introduced the following functions:
- - MSG_task_isend()
- - MSG_task_irecv()
- - MSG_comm_test()
- - MSG_comm_wait()
- - MSG_comm_waitall()
- - MSG_comm_waitany()
- - MSG_comm_destroy()
-
-We refer you to the description of these functions for more details on their usage as well
-as to the example section on \ref MSG_ex_asynchronous_communications.
-
-\subsubsection faq_MIA_thread_synchronization I need to synchronize my MSG processes
-
-You obviously cannot use pthread_mutexes of pthread_conds since we handle every
-scheduling related decision within SimGrid.
-
-In the past (version <=3.3.4) you could do it by playing with
-MSG_process_suspend() and MSG_process_resume() or with fake communications (using MSG_task_get(),
-MSG_task_put() and MSG_task_Iprobe()).
-
-Since version 3.4, you can use classical synchronization structures. See page \ref XBT_synchro or simply check in
-include/xbt/synchro_core.h.
-
-\subsubsection faq_MIA_host_load Where is the get_host_load function hidden in MSG?
+@subsubsection faq_MIA_thread_synchronization How to synchronize my user processes?
+
+It depends on why you want to synchronize them. If you just want to
+have a shared state between your processes, then you probably don't
+need to do anything. User processes never get forcefully interrupted
+in SimGrid (unless you explicitly request the parallel execution of
+user processes -- see @ref options_virt_parallel).
+
+Even if several processes are executed at the exact same time within
+the simulation, they are linearized in reality by default: one process
+always run in an exclusive manner, atomic, uninterrupted until it does
+a simcall (until it ask a service from the simulation kernel). This is
+surprising at first, but things are much easier this way, both for the
+user (who don't have to protect her shared data) and for the kernel
+(that avoid many synchronization issues too). Processes are executed
+concurrently in the simulated realm, but you don't need to bother with
+this in the real realm.
+
+If you really need to synchronize your processes (because it's what
+you are studying or to create an atomic section that spans over
+several simcalls), you obviously cannot use regular synchronization
+mechanisms (pthread_mutexes in C or the synchronized keyword in Java).
+This is because the SimGrid kernel locks all processes and unlock them
+one after the other when they are supposed to run, until they give the
+control back in their simcall. If one of them gets locked by the OS
+before returning the control to the kernel, that's definitively a
+deadlock.
+
+Instead, you should use the synchronization mechanism provided by the
+simulation kernel. This could with a SimGrid mutex, a SimGrid
+condition variables or a SimGrid semaphore, as described in @ref
+msg_synchro (in Java, only semaphores are available). But actually,
+many synchronization patterns can be encoded with communication on
+mailboxes. Typically, if you need one process to notify another one,
+you could use a condition variable or a semphore, but sending a
+message to a specific mailbox does the trick in most cases.
+
+@subsubsection faq_MIA_host_load Where is the get_host_load function hidden in MSG?
There is no such thing because its semantic wouldn't be really
clear. Of course, it is something about the amount of host throughput,
you could also get in real settings to not hinder the realism of your
simulation.
-\verbatim
+@code
double get_host_load() {
m_task_t task = MSG_task_create("test", 0.001, 0, NULL);
double date = MSG_get_clock();
MSG_task_destroy(task);
return (0.001/date);
}
-\endverbatim
+@endcode
Of course, it may not match your personal definition of "host load". In this
case, please detail what you mean on the mailing list, and we will extend
this FAQ section to fit your taste if possible.
-\subsubsection faq_MIA_communication_time How can I get the *real* communication time?
+@subsubsection faq_MIA_communication_time How can I get the *real* communication time?
Communications are synchronous and thus if you simply get the time
before and after a communication, you'll only get the transmission
ready). However, getting the *real* communication time is not really
hard either. The following solution is a good starting point.
-\verbatim
+@code
int sender()
{
m_task_t task = MSG_task_create("Task", task_comp_size, task_comm_size,
MSG_task_destroy(task);
return 0;
}
-\endverbatim
+@endcode
-\subsection faq_MIA_SimDag SimDag related questions
+@subsection faq_MIA_SimDag SimDag related questions
-\subsubsection faq_SG_comm Implementing communication delays between tasks.
+@subsubsection faq_SG_comm Implementing communication delays between tasks.
A classic question of SimDag newcomers is about how to express a
communication delay between tasks. The thing is that in SimDag, both
create 3 SD_tasks: t1, t2 and c and add dependencies in the following
way:
-\verbatim
-SD_task_dependency_add(NULL, NULL, t1, c);
-SD_task_dependency_add(NULL, NULL, c, t2);
-\endverbatim
+@code
+SD_task_dependency_add(t1, c);
+SD_task_dependency_add(c, t2);
+@endcode
This way task t2 cannot start before the termination of communication c
which in turn cannot start before t1 ends.
for example) and build a communication matrix that should look like
[0;amount ; 0; 0].
-\subsubsection faq_SG_DAG How to implement a distributed dynamic scheduler of DAGs.
+@subsubsection faq_SG_DAG How to implement a distributed dynamic scheduler of DAGs.
Distributed is somehow "contagious". If you start making distributed
decisions, there is no way to handle DAGs directly anymore (unless I
distributed. Here is an example of how you could do that. Assume T1
has to be done before T2.
-\verbatim
+@code
int your_agent(int argc, char *argv[] {
...
T1 = MSG_task_create(...);
}
}
}
-\endverbatim
+@endcode
If you decide that the distributed part is not that much important and that
DAG is really the level of abstraction you want to work with, then you should
-give a try to \ref SD_API.
-
-\subsection faq_MIA_generic Generic features
-
-\subsubsection faq_more_processes Increasing the amount of simulated processes
-
-Here are a few tricks you can apply if you want to increase the amount
-of processes in your simulations.
-
- - <b>A few thousands of simulated processes</b> (soft tricks)\n
- SimGrid can use either pthreads library or the UNIX98 contexts. On
- most systems, the number of pthreads is limited and then your
- simulation may be limited for a stupid reason. This is especially
- true with the current linux pthreads, and I cannot get more than
- 2000 simulated processes with pthreads on my box. The UNIX98
- contexts allow me to raise the limit to 25,000 simulated processes
- on my laptop.\n\n
- The <tt>--with-context</tt> option of the <tt>./configure</tt>
- script allows you to choose between UNIX98 contexts
- (<tt>--with-context=ucontext</tt>) and the pthread version
- (<tt>--with-context=pthread</tt>). The default value is ucontext
- when the script detect a working UNIX98 context implementation. On
- Windows boxes, the provided value is discarded and an adapted
- version is picked up.\n\n
- We experienced some issues with contexts on some rare systems
- (solaris 8 and lower or old alpha linuxes comes to mind). The main
- problem is that the configure script detect the contexts as being
- functional when it's not true. If you happen to use such a system,
- switch manually to the pthread version, and provide us with a good
- patch for the configure script so that it is done automatically ;)
-
- - <b>Hundred thousands of simulated processes</b> (hard-core tricks)\n
- As explained above, SimGrid can use UNIX98 contexts to represent
- and handle the simulated processes. Thanks to this, the main
- limitation to the number of simulated processes becomes the
- available memory.\n\n
- Here are some tricks I had to use in order to run a token ring
- between 25,000 processes on my laptop (1Gb memory, 1.5Gb swap).\n
- - First of all, make sure your code runs for a few hundreds
- processes before trying to push the limit. Make sure it's
- valgrind-clean, i.e. that valgrind does not report neither memory
- error nor memory leaks. Indeed, numerous simulated processes
- result in *fat* simulation hindering debugging.
- - It was really boring to write 25,000 entries in the deployment
- file, so I wrote a little script
- <tt>examples/gras/mutual_exclusion/simple_token/make_deployment.pl</tt>, which you may
- want to adapt to your case. You could also think about hijacking
- the SURFXML parser (have look at \ref pf_flexml_bypassing).
- - The deployment file became quite big, so I had to do what is in
- the FAQ entry \ref faq_flexml_limit
- - Each UNIX98 context has its own stack entry. As debugging this is
- quite hairy, the default value is a bit overestimated so that
- user doesn't get into trouble about this. You want to tune this
- size to increase the number of processes. This is the
- <tt>STACK_SIZE</tt> define in
- <tt>src/xbt/xbt_context_sysv.c</tt>, which is 128kb by default.
- Reduce this as much as you can, but be warned that if this value
- is too low, you'll get a segfault. The token ring example, which
- is quite simple, runs with 40kb stacks.
- - You may tweak the logs to reduce the stack size further. When
- logging something, we try to build the string to display in a
- char array on the stack. The size of this array is constant (and
- equal to XBT_LOG_BUFF_SIZE, defined in include/xbt/log/h). If the
- string is too large to fit this buffer, we move to a dynamically
- sized buffer. In which case, we have to traverse one time the log
- event arguments to compute the size we need for the buffer,
- malloc it, and traverse the argument list again to do the actual
- job.\n
- The idea here is to move XBT_LOG_BUFF_SIZE to 1, forcing the logs
- to use a dynamic array each time. This allows us to lower further
- the stack size at the price of some performance loss...\n
- This allowed me to run the reduce the stack size to ... 4k. Ie,
- on my 1Gb laptop, I can run more than 250,000 processes!
-
-\subsubsection faq_MIA_batch_scheduler Is there a native support for batch schedulers in SimGrid?
+give a try to @ref SD_API.
+
+@subsection faq_MIA_generic Generic features
+
+@subsubsection faq_MIA_batch_scheduler Is there a native support for batch schedulers in SimGrid?
No, there is no native support for batch schedulers and none is
planned because this is a very specific need (and doing it in a
and put his code in the contrib directory of our SVN so that other can
keep working on it. You may find inspiring ideas in it.
-\subsubsection faq_MIA_checkpointing I need a checkpointing thing
+@subsubsection faq_MIA_checkpointing I need a checkpointing thing
Actually, it depends on whether you want to checkpoint the simulation, or to
simulate checkpoints.
The first one could help if your simulation is a long standing process you
want to keep running even on hardware issues. It could also help to
<i>rewind</i> the simulation by jumping sometimes on an old checkpoint to
-cancel recent calculations.\n
+cancel recent calculations.@n
Unfortunately, such thing will probably never exist in SG. One would have to
duplicate all data structures because doing a rewind at the simulator level
is very very hard (not talking about the malloc free operations that might
state of an executing task (in particular, the progress made towards
completion) to be saved somewhere. So if a host (and the task executing on
it) fails (cf. #MSG_HOST_FAILURE), then the task can be restarted
-from the last checkpoint.\n
+from the last checkpoint.@n
Actually, such a thing does not exist in SimGrid either, but it's just
because we don't think it is fundamental and it may be done in the user code
MSG_task_get_remaining_computation()), or fragment the task in smaller
subtasks.
-\subsection faq_platform Platform building and Dynamic resources
+@subsection faq_platform Platform building and Dynamic resources
-\subsubsection faq_platform_example Where can I find SimGrid platform files?
+@subsubsection faq_platform_example Where can I find SimGrid platform files?
There are several little examples in the archive, in the examples/msg
directory. From time to time, we are asked for other files, but we
have available, as well as the Simulacrum simulator, meant to generate
SimGrid platforms using all classical generation algorithms.
-\subsubsection faq_platform_alnem How can I automatically map an existing platform?
+@subsubsection faq_platform_alnem How can I automatically map an existing platform?
We are working on a project called ALNeM (Application-Level Network
Mapper) which goal is to automatically discover the topology of an
This tool is not ready yet, but it move quite fast forward. Just stay
tuned.
-\subsubsection faq_platform_synthetic Generating synthetic but realistic platforms
+@subsubsection faq_platform_synthetic Generating synthetic but realistic platforms
The third possibility to get a platform file (after manual or
automatic mapping of real platforms) is to generate synthetic
assessed. Please keep this fact in mind when using it.
-
-
-\section faq_troubleshooting Troubleshooting
-
-\subsection faq_trouble_changelog The feature X stopped to work after my last update
+@subsubsection faq_platform_random Using random variable for the resource power or availability
+
+The best way to model the resouce power using a random variable is to
+use an availability trace that is directed by a probability
+distribution. This can be done using the function
+tmgr_trace_generator_value() below. The date and value generators is
+created with one of tmgr_event_generator_new_uniform(),
+tmgr_event_generator_new_exponential() or
+tmgr_event_generator_new_weibull() (if you need other generators,
+adding them to src/surf/trace_mgr.c should be quite trivial and your
+patch will be welcomed). Once your trace is created, you have to
+connect it to the resource with the function
+sg_platf_new_trace_connect().
+
+That the process is very similar if you want to model the
+resource availability with a random variable (deciding whether it's
+on/off instead of deciding its speed) using the function
+tmgr_trace_generator_state() or tmgr_trace_generator_avail_unavail()
+instead of tmgr_trace_generator_value().
+
+Unfortunately, all this is currently lacking a proper documentation,
+and there is even no proper example of use. You'll thus have to check
+the header file include/simgrid/platf.h and experiment a bit by
+yourself. The following code should be a good starting point, and
+contributing a little clean example would be a good way to help the
+SimGrid project.
+
+@code
+tmgr_trace_generator_value("mytrace",tmgr_event_generator_new_exponential(.5)
+ tmgr_event_generator_new_uniform(100000,9999999));
+
+sg_platf_trace_connect_cbarg_t myconnect = SG_PLATF_TRACE_CONNECT_INITIALIZER;
+myconnect.kind = SURF_TRACE_CONNECT_KIND_BANDWIDTH;
+myconnect.trace = "mytrace";
+myconnect.element = "mylink";
+
+sg_platf_trace_connect(myconnect);
+@endcode
+
+@section faq_troubleshooting Troubleshooting
+
+@subsection faq_trouble_changelog The feature X stopped to work after my last update
I guess that you want to read the ChangeLog file, that always contains
all the information that could be important to the users during the
file that highlights the most important changes) even before you
upgrade your copy of SimGrid, too.
-Backward compatibility is very important to us, as we want to provide
-a scientific tool allowing to evaluate the code you write in several
-years, too. That being said, we sometimes change the interface to make
-them more usable to the users. When we do so, we always keep the old
-interface as DEPRECATED. If you still want to use them, you want to
-define the SIMGRID_DEPRECATED preprocessor symbol before loading the
-SimGrid files:
-
-@verbatim
-#define SIMGRID_DEPRECATED
-#include <msg/msg.h>
-@endverbatim
+We do our best to maintain the backward compatibility, but we
+sometimes have to fix the things that are too broken. If we happen to
+kill a feature that you were using, we are sorry. We think that you
+should update to the new way of doing things, but if you can't afford
+it, that's ok. Just stick to the last version that were working for
+you, and have a pleasant day.
-\subsection faq_trouble_lib_compil SimGrid compilation and installation problems
+@subsection faq_trouble_lib_compil SimGrid compilation and installation problems
-\subsubsection faq_trouble_lib_config cmake fails!
+@subsubsection faq_trouble_lib_config cmake fails!
We know only one reason for the configure to fail:
- - <b>You are using a broken build environment</b>\n
- If symptom is that the configury magic complains about gcc not being able to build
- executables, you are probably missing the libc6-dev package. Damn Ubuntu.
+ - <b>You are using a broken build environment</b>@n
+ Try updating your cmake version. If symptom is that the configury
+ magic complains about gcc not being able to build executables, you
+ are probably missing the libc6-dev package. Damn Ubuntu.
If you experience other kind of issue, please get in touch with us. We are
always interested in improving our portability to new systems.
-\subsubsection faq_trouble_distcheck Dude! "ctest" fails on my machine!
+@subsubsection faq_trouble_distcheck Dude! "ctest" fails on my machine!
Don't assume we never run this target, because we do. Check
http://cdash.inria.fr/CDash/index.php?project=Simgrid (click on
If it's failing on your machine in a way not experienced by the
autobuilders above, please drop us a mail on the mailing list so that
-we can check it out. Make sure to read \ref faq_bugrepport before you
+we can check it out. Make sure to read @ref faq_bugrepport before you
do so.
-\subsection faq_trouble_compil User code compilation problems
+@subsection faq_trouble_compil User code compilation problems
-\subsubsection faq_trouble_err_logcat "gcc: _simgrid_this_log_category_does_not_exist__??? undeclared (first use in this function)"
+@subsubsection faq_trouble_err_logcat "gcc: _simgrid_this_log_category_does_not_exist__??? undeclared (first use in this function)"
-This is because you are using the log mecanism, but you didn't created
-any default category in this file. You should refer to \ref XBT_log
+This is because you are using the log mechanism, but you didn't created
+any default category in this file. You should refer to @ref XBT_log
for all the details, but you simply forgot to call one of
XBT_LOG_NEW_DEFAULT_CATEGORY() or XBT_LOG_NEW_DEFAULT_SUBCATEGORY().
-\subsubsection faq_trouble_pthreadstatic "gcc: undefined reference to pthread_key_create"
+@subsubsection faq_trouble_pthreadstatic "gcc: undefined reference to pthread_key_create"
This indicates that one of the library SimGrid depends on (libpthread
here) was missing on the linking command line. Dependencies of
quite impossible that you see this message when doing dynamic linking.
If you compile your code statically (and if you use a pthread version
-of SimGrid -- see \ref faq_more_processes), you must absolutely
+of SimGrid), you must absolutely
specify <tt>-lpthread</tt> on the linker command line. As usual, this should
come after <tt>-lsimgrid</tt> on this command line.
-\subsubsection faq_trouble_lib_msg_deprecated "gcc: undefined reference to MSG_*"
-
-Since version 3.7 all the m_channel_t mecanism is deprecated. So functions
-about this mecanism may get removed in future releases.
-
-List of functions:
-
-\li XBT_PUBLIC(int) MSG_get_host_number(void);
-
-\li XBT_PUBLIC(m_host_t *) MSG_get_host_table(void);
-
-\li XBT_PUBLIC(MSG_error_t) MSG_get_errno(void);
-
-\li XBT_PUBLIC(MSG_error_t) MSG_task_get(m_task_t * task, m_channel_t channel);
-
-\li XBT_PUBLIC(MSG_error_t) MSG_task_get_with_timeout(m_task_t * task, m_channel_t channel, double max_duration);
-
-\li XBT_PUBLIC(MSG_error_t) MSG_task_get_from_host(m_task_t * task, int channel, m_host_t host);
-
-\li XBT_PUBLIC(MSG_error_t) MSG_task_get_ext(m_task_t * task, int channel, double max_duration, m_host_t host);
-
-\li XBT_PUBLIC(MSG_error_t) MSG_task_put(m_task_t task, m_host_t dest, m_channel_t channel);
-
-\li XBT_PUBLIC(MSG_error_t) MSG_task_put_bounded(m_task_t task, m_host_t dest, m_channel_t channel, double max_rate);
+@subsection faq_trouble_errors Runtime error messages
-\li XBT_PUBLIC(MSG_error_t) MSG_task_put_with_timeout(m_task_t task, m_host_t dest, m_channel_t channel, double max_duration);
-
-\li XBT_PUBLIC(int) MSG_task_Iprobe(m_channel_t channel);
-
-\li XBT_PUBLIC(int) MSG_task_probe_from(m_channel_t channel);
-
-\li XBT_PUBLIC(int) MSG_task_probe_from_host(int channel, m_host_t host);
-
-\li XBT_PUBLIC(MSG_error_t) MSG_set_channel_number(int number);
-
-\li XBT_PUBLIC(int) MSG_get_channel_number(void);
-
-If you want them you have to compile Simgrid v3.7 with option "-Denable_msg_deprecated=ON".
-Using them should print warning to inform what new function you have to use.
-
-\subsection faq_trouble_errors Runtime error messages
-
-\subsubsection faq_flexml_limit "surf_parse_lex: Assertion `next limit' failed."
-
-This is because your platform file is too big for the parser.
-
-Actually, the message comes directly from FleXML, the technology on top of
-which the parser is built. FleXML has the bad idea of fetching the whole
-document in memory before parsing it. And moreover, the memory buffer size
-must be determined at compilation time.
-
-We use a value which seems big enough for our need without bloating the
-simulators footprints. But of course your mileage may vary. In this case,
-just edit src/surf/surfxml.l modify the definition of
-FLEXML_BUFFERSTACKSIZE. E.g.
-
-\verbatim
-#define FLEXML_BUFFERSTACKSIZE 1000000000
-\endverbatim
-
-Then recompile and everything should be fine, provided that your version of
-Flex is recent enough (>= 2.5.31). If not the compilation process should
-warn you.
-
-A while ago, we worked on FleXML to reduce a bit its memory consumption, but
-these issues remain. There is two things we should do:
-
- - use a dynamic buffer instead of a static one so that the only limit
- becomes your memory, not a stupid constant fixed at compilation time
- (maybe not so difficult).
- - change the parser so that it does not need to get the whole file in
- memory before parsing
- (seems quite difficult, but I'm a complete newbe wrt flex stuff).
-
-These are changes to FleXML itself, not SimGrid. But since we kinda hijacked
-the development of FleXML, I can grant you that any patches would be really
-welcome and quickly integrated.
-
-<b>Update:</b> A new version of FleXML (1.7) was released. Most of the work
-was done by William Dowling, who use it in his own work. The good point is
-that it now use a dynamic buffer, and that the memory usage was greatly
-improved. The downside is that William also changed some things internally,
-and it breaks the hack we devised to bypass the parser, as explained in
-\ref pf_flexml_bypassing. Indeed, this is not a classical usage of the
-parser, and Will didn't imagine that we may have used (and even documented)
-such a crude usage of FleXML. So, we now have to repair the bypassing
-functionality to use the latest FleXML version and fix the memory usage in
-SimGrid.
-
-\subsubsection faq_trouble_errors_big_fat_warning I'm told that my XML files are too old.
+@subsubsection faq_trouble_errors_big_fat_warning I'm told that my XML files are too old.
The format of the XML platform description files is sometimes
improved. For example, we decided to change the units used in SimGrid
That is why the XML files are versionned using the 'version' attribute
of the root tag. Currently, it should read:
-\verbatim
- <platform version="2">
-\endverbatim
+@verbatim
+ <platform version="4">
+@endverbatim
If your files are too old, you can use the simgrid_update_xml.pl
script which can be found in the tools directory of the archive.
-\subsection faq_trouble_valgrind Valgrind-related and other debugger issues
+@subsection faq_trouble_debug Debugging SMPI applications
-If you don't, you really should use valgrind to debug your code, it's
-almost magic.
+In order to debug SMPI programs, you can use the following options:
-\subsubsection faq_trouble_vg_longjmp longjmp madness in valgrind
+- <b>-wrapper 'gdb --args'</b>: this option is used to use a wrapper
+ in order to call the SMPI process. Good candidates for this options
+ are "gdb --args", "valgrind", "rr record", "strace", etc;
-This is when valgrind starts complaining about longjmp things, just like:
+- <b>-foreground</b>: this options gives the debugger access to the terminal
+ which is needed in order to use an interactive debugger.
-\verbatim ==21434== Conditional jump or move depends on uninitialised value(s)
-==21434== at 0x420DBE5: longjmp (longjmp.c:33)
-==21434==
-==21434== Use of uninitialised value of size 4
-==21434== at 0x420DC3A: __longjmp (__longjmp.S:48)
-\endverbatim
+Both options are needed in order to run the SMPI process under GDB.
-This is the sign that you didn't used the exception mecanism well. Most
-probably, you have a <tt>return;</tt> somewhere within a <tt>TRY{}</tt>
-block. This is <b>evil</b>, and you must not do this. Did you read the section
-about \ref XBT_ex??
+@subsection faq_trouble_valgrind Valgrind-related and other debugger issues
-\subsubsection faq_trouble_vg_libc Valgrind spits tons of errors about backtraces!
+If you don't, you really should use valgrind to debug your code, it's
+almost magic.
+
+@subsubsection faq_trouble_vg_libc Valgrind spits tons of errors about backtraces!
It may happen that valgrind, the memory debugger beloved by any decent C
programmer, spits tons of warnings like the following :
-\verbatim ==8414== Conditional jump or move depends on uninitialised value(s)
+@verbatim ==8414== Conditional jump or move depends on uninitialised value(s)
==8414== at 0x400882D: (within /lib/ld-2.3.6.so)
==8414== by 0x414EDE9: (within /lib/tls/i686/cmov/libc-2.3.6.so)
==8414== by 0x400B105: (within /lib/ld-2.3.6.so)
==8414== by 0x80764C1: xbt_dictelm_get (dict_elm.c:732)
==8414== by 0x8079010: xbt_cfg_register (config.c:208)
==8414== by 0x806821B: MSG_config (msg_config.c:42)
-\endverbatim
+@endverbatim
This problem is somewhere in the libc when using the backtraces and there is
very few things we can do ourselves to fix it. Instead, here is how to tell
your personnal mileage (change 2.3.6 to the actual version you are using,
which you can retrieve with a simple "ls /lib/ld*.so").
-\verbatim {
+@verbatim {
name: Backtrace madness
Memcheck:Cond
obj:/lib/ld-2.3.6.so
fun:do_dlopen
fun:dlerror_run
fun:__libc_dlopen_mode
-}\endverbatim
+}@endverbatim
Then, you have to specify valgrind to use this suppression file by passing
the <tt>--suppressions=$HOME/.valgrind.supp</tt> option on the command line.
happen to be my personnal settings. Check the valgrind documentation for
more information.
-\verbatim export VALGRIND_OPTS="--leak-check=yes --leak-resolution=high --num-callers=40 --tool=memcheck --suppressions=$HOME/.valgrind.supp" \endverbatim
+@verbatim export VALGRIND_OPTS="--leak-check=yes --leak-resolution=high --num-callers=40 --tool=memcheck --suppressions=$HOME/.valgrind.supp" @endverbatim
-\subsubsection faq_trouble_backtraces Truncated backtraces
+@subsubsection faq_trouble_backtraces Truncated backtraces
When debugging SimGrid, it's easier to pass the
--disable-compiler-optimization flag to the configure if valgrind or
production (before launching your 1252135 experiments), or everything
will run only one half of the true SimGrid potential.
-\subsection faq_deadlock There is a deadlock in my code!!!
+@subsection faq_deadlock There is a deadlock in my code!!!
Unfortunately, we cannot debug every code written in SimGrid. We
furthermore believe that the framework provides ways enough
-information to debug such informations yourself. If the textual output
-is not enough, Make sure to check the \ref faq_visualization FAQ entry to see
+information to debug such information yourself. If the textual output
+is not enough, Make sure to check the @ref faq_visualization FAQ entry to see
how to get a graphical one.
Now, if you come up with a really simple example that deadlocks and
on your side... We have plenty of FAQ entries to redact and new
features to implement for the impenitents! ;)
-\subsection faq_surf_network_latency I get weird timings when I play with the latencies.
+@subsection faq_surf_network_latency I get weird timings when I play with the latencies.
OK, first of all, remember that units should be Bytes, Flops and
Seconds. If you don't use such units, some SimGrid constants (e.g. the
Here is what happens with a single transfer of size L on a link
(bw,lat) when nothing else happens.
-\verbatim
+@verbatim
0-----lat--------------------------------------------------t
|-----|**** real_bw =min(bw,SG_TCP_CTE_GAMMA/(2*lat)) *****|
-\endverbatim
+@endverbatim
In more complex situations, this min is the solution of a complex
max-min linear system. Have a look
competing on a saturated link receive an amount of bandwidth inversely
proportional to their round trip time.
-\subsection faq_bugrepport So I've found a bug in SimGrid. How to report it?
+@subsection faq_bugrepport So I've found a bug in SimGrid. How to report it?
We do our best to make sure to hammer away any bugs of SimGrid, but this is
still an academic project so please be patient if/when you find bugs in it.
http://www.chiark.greenend.org.uk/~sgtatham/bugs.html (it is not SimGrid
specific at all, but it's full of good advices).
-\author Da SimGrid team <simgrid-devel@lists.gforge.inria.fr>
-
*/
-
-******************************************************************
-* OLD CRUFT NOT USED ANYMORE *
-******************************************************************
-
-
-subsection faq_crosscompile Cross-compiling a Windows DLL of SimGrid from linux
-
-At the moment, we do not distribute Windows pre-compiled version of SimGrid
-because the support for this platform is still experimental. We know that
-some parts of the GRAS environment do not work, and we think that the others
-environments (MSG and SD) have good chances to work, but we didn't test
-ourselves. This section explains how we generate the SimGrid DLL so that you
-can build it for yourself. First of all, you need to have a version more
-recent than 3.1 (ie, a SVN version as time of writting).
-
-In order to cross-compile the package to windows from linux, you need to
-install mingw32 (minimalist gnu win32). On Debian, you can do so by
-installing the packages mingw32 (compiler), mingw32-binutils (linker and
-so), mingw32-runtime.
-
-You can use the VPATH support of configure to compile at the same time for
-linux and windows without dupplicating the source nor cleaning the tree
-between each. Just run bootstrap (if you use the SVN) to run the autotools.
-Then, create a linux and a win directories. Then, type:
-\verbatim cd linux; ../configure --srcdir=.. <usual configure flags>; make; cd ..
-cd win; ../configure --srcdir=.. --host=i586-mingw32msvc <flags>; make; cd ..
-\endverbatim
-The trick to VPATH builds is to call configure from another directory,
-passing it an extra --srcdir argument to tell it where all the sources are.
-It will understand you want to use VPATH. Then, the trick to cross-compile
-is simply to add a --host argument specifying the target you want to build
-for. The i586-mingw32msvc string is what you have to pass to use the mingw32
-environment as distributed in Debian.
-
-After that, you can run all make targets from both directories, and test
-easily that what you change for one arch does not break the other one.
-
-It is possible that this VPATH build thing breaks from time to time in the
-SVN since it's quite fragile, but it's granted to work in any released
-version. If you experience problems, drop us a mail.
-
-Another possible source of issue is that at the moment, building the
-examples request to use the gras_stub_generator tool, which is a compiled
-program, not a script. In cross-compilation, you need to cross-execute with
-wine for example, which is not really pleasant. We are working on this, but
-in the meanwhile, simply don't build the examples in cross-compilation
-(<tt>cd src</tt> before running make).
-
-Program (cross-)compiled with mingw32 do request an extra DLL at run-time to be
-usable. For example, if you want to test your build with wine, you should do
-the following to put this library where wine looks for DLLs.
-\verbatim
-cp /usr/share/doc/mingw32-runtime/mingwm10.dll.gz ~/.wine/c/windows/system/
-gunzip ~/.wine/c/windows/system/mingwm10.dll.gz
-\endverbatim
-
-The DLL is built in src/.libs, and installed in the <i>prefix</i>/bin directory
-when you run make install.
-
-If you want to use it in a native project on windows, you need to use
-simgrid.dll and mingwm10.dll. For each DLL, you need to build .def file
-under linux (listing the defined symbols), and convert it into a .lib file
-under windows (specifying this in a way that windows compilers like). To
-generate the def files, run (under linux):
-\verbatim echo "LIBRARY libsimgrid-0.dll" > simgrid.def
-echo EXPORTS >> simgrid.def
-nm libsimgrid-0.dll | grep ' T _' | sed 's/.* T _//' >> simgrid.def
-nm libsimgrid-0.dll | grep ' D _' | sed 's/.* D _//' | sed 's/$/ DATA/' >> simgrid.def
-
-echo "LIBRARY mingwm10.dll" > mingwm10.def
-echo EXPORTS >> mingwm10.def
-nm mingwm10.dll | grep ' T _' | sed 's/.* T _//' >> mingwm10.def
-nm mingwm10.dll | grep ' D _' | sed 's/.* D _//' | sed 's/$/ DATA/' >> mingwm10.def
-\endverbatim
-
-To create the import .lib files, use the <tt>lib</tt> windows tool (from
-MSVC) the following way to produce simgrid.lib and mingwm10.lib
-\verbatim lib /def:simgrid.def
-lib /def:mingwm10.def
-\endverbatim
-
-If you happen to use Borland C Builder, the right command line is the
-following (note that you don't need any file.def to get this working).
-\verbatim implib simgrid.lib libsimgrid-0.dll
-implib mingwm10.lib mingwm10.dll
-\endverbatim
-
-Then, set the following parameters in Visual C++ 2005:
-Linker -> Input -> Additional dependencies = simgrid.lib mingwm10.lib
-
-Just in case you wonder how to generate a DLL from libtool in another
-project, we added -no-undefined to any lib*_la_LDFLAGS variables so that
-libtool accepts to generate a dynamic library under windows. Then, to make
-it true, we pass any dependencies (such as -lws2 under windows or -lpthread
-on need) on the linking line. Passing such deps is a good idea anyway so
-that they get noted in the library itself, avoiding the users to know about
-our dependencies and put them manually on their compilation line. Then we
-added the AC_LIBTOOL_WIN32_DLL macro just before AC_PROG_LIBTOOL in the
-configure.ac. It means that we exported any symbols which need to be.
-Nowadays, functions get automatically exported, so we don't need to load our
-header files with tons of __declspec(dllexport) cruft. We only need to do so
-for data, but there is no public data in SimGrid so we are good.
