Difference between revisions of "Building MPICH For Development"

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(Use VPATH Builds)
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I recommend using <code>--enable-strict=all</code> or <code>--enable-strict=posix</code> for those situations where <code>all</code> is too constraining and you know what you are doing.  This strictness will also help to catch general programming errors, not just portability issues.
 
I recommend using <code>--enable-strict=all</code> or <code>--enable-strict=posix</code> for those situations where <code>all</code> is too constraining and you know what you are doing.  This strictness will also help to catch general programming errors, not just portability issues.
 +
 +
== Use -jN ==
 +
Run <code>make -jN</code> where <code>N</code> is some number like 4 or 8.  This only works starting with MPICH2-1.5, since prior to that the build system used an approach that was not parallel-make safe.
  
 
== Use ccache ==
 
== Use ccache ==
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<pre>
 
<pre>
 
--disable-f77
 
--disable-f77
--disable-f90
+
--disable-fc
 
--disable-cxx
 
--disable-cxx
 
--disable-romio
 
--disable-romio
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Next change to the <code>multiple</code> directory and issue the same commands but replace "single" with "multiple" everywhere.  You now have two builds of MPICH from the same source tree.
 
Next change to the <code>multiple</code> 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 <code>make dependencies</code> before <code>make</code> 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 <code>make</code>.  Otherwise you might need to <code>make clean</code> before running <code>make</code> to ensure that you have a consistent build.
 
  
 
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<!-- vim: set ft=wikipedia tw=0 : -->

Revision as of 00:15, 9 January 2013

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

Configure with --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 (goodell@) usually build with: --enable-g=dbg,mem,meminit,handle or --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: --enable-strict.

I recommend using --enable-strict=all or --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.

Use -jN

Run make -jN where N is some number like 4 or 8. This only works starting with MPICH2-1.5, since prior to that the build system used an approach that was not parallel-make safe.

Use ccache

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-fc
--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 git version of the code you will need to do an ./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/single and /foo/bar/multiple. Change to the single directory and run

 ../mpich-trunk/configure --prefix=/foo/bar/single-installed --enable-threads=single

Then make and make install.

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.