Building MPICH For Development
When developing MPICH itself it is often useful to build the library differently than you would for production use. This page aggregates several tips and tricks for making your development life easier when working with MPICH.
Enable Debugging Symbols
--enable-g=dbg to get debugging symbols included in the build.
--enable-g=option - Control the level of debugging support in the MPICH implementation. option is a list of comma separated names including none - No debugging mem - Memory usage tracing handle - Trace handle operations dbg - Add compiler flag, -g, to CFLAGS, CXXFLAGS FFLAGS and F90FLAGS. log - Enable debug event logging meminit - Preinitialize memory associated structures and unions to eliminate access warnings from programs like valgrind mutex - Enable error checking on pthread mutexes all - All of the above choices
Personally I ([email protected]) usually build with:
--enable-g=all. I will drop some or all of these for performance testing. I also find that it is useful to include
CFLAGS=-g3 to enable gcc to expand macros.
Configure With "strict"
MPICH is a very portable project and one of the only ways to ensure that we are developing portable code on a permissive compiler like gcc is to configure gcc to be as strict and pedantic as possible. The MPICH configure provides an option to make this easy:
I recommend using
--enable-strict=posix for those situations where
all is too constraining and you know what you are doing. This strictness will also help to catch general programming errors, not just portability issues.
When developing MPICH it's not uncommon to need to
make clean or
make distclean fairly often for various reasons. One way to help reduce the time drain that this can be is to use ccache. On my desktop this utility cuts my build times in half or better. For setup just read the docs on the ccache site, they are pretty good.
Don't Build Unnecessary Code
If you know you won't need a particular feature of MPICH then you might be able to disable it to speed up compilation or to prevent configure from complaining. For example you can pick and choose from the following list of systems that can be disabled:
--disable-f77 --disable-f90 --disable-cxx --disable-romio
The first three are useful if you only need the MPI C language bindings. They disable the Fortran and C++ bindings. The last one disables MPI-IO support.
Use VPATH Builds
You can build several versions of MPICH from the same source tree by doing what's known as a "VPATH build". Let's assume you have your source in some directory like:
/foo/bar/mpich-trunk. If you are using an svn version of the code you will need to do a ./maint/autogen.sh in this source directory (see here.
Now let's say that you want to build two versions, one with a supported thread level of MPI_THREAD_SINGLE and one with MPI_THREAD_MULTIPLE. You would create two directories that are not in the source directory like
/foo/bar/multiple. Change to the
single directory and run
../mpich-trunk/configure --prefix=/foo/bar/single-installed --enable-threads=single
Next change to the
multiple directory and issue the same commands but replace "single" with "multiple" everywhere. You now have two builds of MPICH from the same source tree.
Use Makefile Dependency Tracking
For non-VPATH builds, you can run
make dependencies before
make and you will get dependency tracking in the build process. This is useful because if you make a change to a header file then the appropriate including files will be updated the next time you run
make. Otherwise you might need to
make clean before running
make to ensure that you have a consistent build.