./configure --enable-maintainer-mode
make dist \endverbatim
-\subsection faq_setting Setting up your own code
+\subsection faq_setting_MSG Setting up your own MSG code
Do not build your simulator by modifying the SimGrid examples. Go
outside the SimGrid source tree and create your own working directory
previous example should be enough for a first try but you may want to
perform some more complex compilations...
+\subsection faq_setting_GRAS Setting up your own GRAS code
+
+If you use the GRAS interface instead of the MSG one, then previous section
+is not the better source of information. Instead, you should check the GRAS
+tutorial in general, and the \ref GRAS_tut_tour_setup in particular.
+
+\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 CVS 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 CVS) 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
+CVS 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 builded in src/.libs, and installed in the <prefix>/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
+
+echo "LIBRARY mingwm10.dll" > mingwm10.def
+echo EXPORTS >> mingwm10.def
+nm mingwm10.dll | grep ' T _' | sed 's/.* T _//' >> mingwm10.def
+\endverbatim
+
+To create the import .lib files, use the <tt>lib</tt> windows tool the
+following way to produce simgrid.lib and mingwm10.lib
+\verbatim lib /def:simgrid.def
+lib /def:mingwm10.def
+\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.
+
\section faq_simgrid I'm new to SimGrid. I have some questions. Where should I start?
You are at the right place... Having a look to these
If none of the above apply, please drop us a mail on the mailing list so
that we can check it out.
-\subsection faq_longjmp longjmp madness
+\subsection faq_longjmp longjmp madness in valgrind
This is when valgrind starts complaining about longjmp things, just like:
block. This is <b>evil</b>, and you must not do this. Did you read the section
about \ref XBT_ex??
+\subsection faq_valgrind Valgrind spits tons of errors!
+
+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)
+==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 0x414F937: _dl_open (in /lib/tls/i686/cmov/libc-2.3.6.so)
+==8414== by 0x4150F4C: (within /lib/tls/i686/cmov/libc-2.3.6.so)
+==8414== by 0x400B105: (within /lib/ld-2.3.6.so)
+==8414== by 0x415102D: __libc_dlopen_mode (in /lib/tls/i686/cmov/libc-2.3.6.so)
+==8414== by 0x412D6B9: backtrace (in /lib/tls/i686/cmov/libc-2.3.6.so)
+==8414== by 0x8076446: xbt_dictelm_get_ext (dict_elm.c:714)
+==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
+
+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
+valgrind to ignore the error. Add the following to your ~/.valgrind.supp (or
+create this file on need). Make sure to change the obj line according to
+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 {
+ name: Backtrace madness
+ Memcheck:Cond
+ obj:/lib/ld-2.3.6.so
+ fun:dl_open_worker
+ fun:_dl_open
+ fun:do_dlopen
+ fun:dlerror_run
+ fun:__libc_dlopen_mode
+}\endverbatim
+
+Then, you have to specify valgrind to use this suppression file by passing
+the <tt>--suppressions=$HOME/.valgrind.supp</tt> option on the command line.
+You can also add the following to your ~/.bashrc so that it gets passed
+automatically. Actually, it passes a bit more options to valgrind, and this
+happen to be my personnal settings. Check the valgrind documentation for
+more information.
+
+\verbatim export VALGRIND_OPTS="--leak-check=yes --leak-resolution=high --num-callers=40 --tool=memcheck --suppressions=$HOME/.valgrind.supp" \endverbatim
+
\subsection faq_flexml_limit I get the message "surf_parse_lex: Assertion `next<limit' failed."
This is because your platform file is too big for the parser.
before the client get a chance to read them (use gras_os_sleep() to delay
the server), or the server died awfully before the client got the data.
-\subsection faq_valgrind Valgrind spits tons of errors!
-
-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)
-==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 0x414F937: _dl_open (in /lib/tls/i686/cmov/libc-2.3.6.so)
-==8414== by 0x4150F4C: (within /lib/tls/i686/cmov/libc-2.3.6.so)
-==8414== by 0x400B105: (within /lib/ld-2.3.6.so)
-==8414== by 0x415102D: __libc_dlopen_mode (in /lib/tls/i686/cmov/libc-2.3.6.so)
-==8414== by 0x412D6B9: backtrace (in /lib/tls/i686/cmov/libc-2.3.6.so)
-==8414== by 0x8076446: xbt_dictelm_get_ext (dict_elm.c:714)
-==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
-
-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
-valgrind to ignore the error. Add the following to your ~/.valgrind.supp (or
-create this file on need). Make sure to change the obj line according to
-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 {
- name: Backtrace madness
- Memcheck:Cond
- obj:/lib/ld-2.3.6.so
- fun:dl_open_worker
- fun:_dl_open
- fun:do_dlopen
- fun:dlerror_run
- fun:__libc_dlopen_mode
-}\endverbatim
-
-Then, you have to specify valgrind to use this suppression file by passing
-the <tt>--suppressions=$HOME/.valgrind.supp</tt> option on the command line.
-You can also add the following to your ~/.bashrc so that it gets passed
-automatically. Actually, it passes a bit more options to valgrind, and this
-happen to be my personnal settings. Check the valgrind documentation for
-more information.
-
-\verbatim export VALGRIND_OPTS="--leak-check=yes --leak-resolution=high --num-callers=40 --tool=memcheck --suppressions=$HOME/.valgrind.supp" \endverbatim
-
\subsection faq_deadlock There is a deadlock !!!
Unfortunately, we cannot debug every code written in SimGrid. We
\endverbatim
You should try to use the surfxml_update.pl script that can be found
<a href="http://gforge.inria.fr/plugins/scmcvs/cvsweb.php/contrib/platform_generation/?cvsroot=cvsroot%2Fsimgrid">here</a>.
-
+
+\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
+SG_TCP_CTE_GAMMA constant used in most network models) won't have the
+right unit and you'll end up with weird results.
+
+Here is what happens with a single transfer of size L on a link
+(bw,lat) when nothing else happens.
+
+\verbatim
+0-----lat--------------------------------------------------t
+|-----|**** real_bw =min(bw,SG_TCP_CTE_GAMMA/(2*lat)) *****|
+\endverbatim
+
+In more complex situations, this min is the solution of a complex
+max-min linear system. Have a look
+<a href="http://lists.gforge.inria.fr/pipermail/simgrid-devel/2006-April/thread.html">here</a>
+and read the two threads "Bug in SURF?" and "Surf bug not
+fixed?". You'll have a few other examples of such computations. You
+can also read "A Network Model for Simulation of Grid Application" by
+Henri Casanova and Loris Marchal to have all the details. The fact
+that the real_bw is smaller than bw is easy to understand. The fact
+that real_bw is smaller than SG_TCP_CTE_GAMMA/(2*lat) is due to the
+window-based congestion mechanism of TCP. With TCP, you can't exploit
+your huge network capacity if you don't have a good round-trip-time
+because of the acks...
+
+Anyway, what you get is t=lat + L/min(bw,SG_TCP_CTE_GAMMA/(2*lat)).
+
+ * if I you set (bw,lat)=(100 000 000, 0.00001), you get t = 1.00001 (you fully
+use your link)
+ * if I you set (bw,lat)=(100 000 000, 0.0001), you get t = 1.0001 (you're on the
+limit)
+ * if I you set (bw,lat)=(100 000 000, 0.001), you get t = 10.001 (ouch!)
+
+This bound on the effective bandwidth of a flow is not the only thing
+that may make your result be unexpected. For example, two flows
+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?
+
+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.
+If you do, the best solution is to drop an email either on the simgrid-user
+or the simgrid-devel mailing list and explain us about the issue. You can
+also decide to open a formal bug report using the
+<a href="https://gforge.inria.fr/tracker/?atid=165&group_id=12&func=browse">relevant
+interface</a>. You need to login on the server to get the ability to submit
+bugs.
+
+We will do our best to solve any problem repported, but you need to help us
+finding the issue. Just telling "it segfault" isn't enough. Telling "It
+segfaults when running the attached simulator" doesn't really help either.
+You may find the following article interesting to see how to repport
+informative bug repports:
+http://www.chiark.greenend.org.uk/~sgtatham/bugs.html (it is not SimGrid
+specific at all, but it's full of good advices).
+
\author Arnaud Legrand (arnaud.legrand::imag.fr)
\author Martin Quinson (martin.quinson::loria.fr)
