#phdeem

This is a wrapper for using the hdeem library from within a MPI context.

##Compilation and Installation

###Prerequisites

To compile this plugin, you need:

• MPI

• libhdeem

• FreeIPMI

###Building

1. Create a build directory

    mkdir build
    cd build
   

2. Invoke CMake

   Simplest possible call:

    cmake ..
   

   If either libhdeem or FreeIPMI are not installed in standard paths, you need to pass hints to CMake. For libhdeem you have to use HDEEM_ROOT_DIR and for FreeIPMI FreeIPMI_ROOT_DIR, e.g.

    cmake .. -DHDEEM_ROOT_DIR=/opt/hdeem/ -DFreeIPMI_ROOT_DIR=/home/user/freeipmi
   

   These can be provided as environment variables to. You can also pass different locations for header files and libraries with HDEEM_INCLUDE_DIR and HDEEM_LIBRARY or FreeIPMI_INCLUDE_DIR and FreeIPMI_LIBRARY resp.

   If you want to build the examples, include BUILD_EXAMPLES=on in your CMake call, or for the tests BUILD_TESTS=on resp., e.g.:

    cmake .. -DBUILD_EXAMPLES=on -DBUILD_TESTS=on
   

3. Invoke make

    make
   

4. Copy the resulting libphdeem.so to a location listed in LD_LIBRARY_PATH or add the current path to LD_LIBRARY_PATH with

    export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:`pwd`
   

##Usage

The usage of phdeem is just the same as the usage of libhdeem. You just have to replace the hdeem_ in the function names with phdeem_ and provide some additional parameters:

• info

  A phdeem_info_t storing the information about the caller for each process. You don't have to worry about the contents of this, it is just for internal context.

• ret_val

  A phdeem_status_t containing the return values of the internally called libhdeem and MPI functions. You can access the values via mpi_ret_value and hdeem_ret_value resp.

They are passed as references to all function calls as shown below:

int ret;
phdeem_info_t info;
phdeem_status_t int_rets;
hdeem_bmc_data_t hdeem_data;

ret = phdeem_init( &hdeem_data, &info, MPI_COMM_WORLD, &int_rets );

The return values of the functions tell you if either

1. everything went fine (PHDEEM_SUCCESS) or

2. the calling process is not the root process on the node and therefore no call to hdeem has been made (PHDEEM_NOT_ROOT) or

3. an error occurred in MPI (PHDEEM_MPI_ERROR) or libhdeem (PHDEEM_HDEEM_ERROR) (with the corresponding return values in ret_val).

For more information take a look at the comments in the header file or the examples.

Note:

hdeem_version() is not mapped at the moment.

Note:

phdeem is not thread-safe!

###Tests

phdeem uses a hash function to determine whether the calling process is the root process on a specific node. This function may collide for some of your node names. If you encounter errors, please check if these are caused by collisions of the hash function.

In order to do that you can use the test_hash program which expects a newline seperated list of node names in a file called nodes.txt and prints the number of dublicates found. You can build the test_hash program by passing -DBUILD_TESTS=on as an argument to you CMake call. If you encounter a non-zero return value, please file an issue on Github.

###Environment variables

None. For environment variables influencing the build, see the Building section.

###If anything fails

1. Check if your hardware has hdeem capability.

2. Write an issue on Github.

3. Write a mail to the author.

##Author

• Philipp Trommler (philipp.trommler at tu-dresden dot de)