WMPI 1.5 Beta

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    The Cluster Configuration
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TCP Device
Shared Memory Device
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   PI Calculation
    MultiPingPong
    Mandelbrot Calculation
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WMPI Shared Memory Device

This device allows processes, running on the same host, to communicate using shared memory.

It allocates a certain amount of memory space at startup, which is used for passing messages between the processes. The amount of memory used limits the size of the biggest message, however the user may adapt the size of the memory space to the program requirements by changing/introducing the WMPI_SHMEM_SIZE environment variable. If the environment variable is not present, then it uses 32 Mbytes.

The maximum number of processes that are allowed is also configurable. The default value is 32, but users may choose another value using the WMPI_SHMEM_UNIVERSE_SIZE environment variable.

Environment Variables

WMPI_SHMEM_SIZE – Memory space available for the device to exchange data. The default size is 32 Mbytes. If you wish to exchange larger messages, you have to set the value of this environment variable to a higher value. The value has to be introduced in bytes.

WMPI_SHMEM_UNIVERSE_SIZE – The maximum number of processes that the device is able to cope with. The default  value is 32 processes.

WMPI_SHMEM_END_POINT – The end point of the shared memory region. The default is the bottom of the address space, unfortunately some other DLLs that the users might load (directly or indirectly) may try to use this space. Hence we have decided to allow the user to choose another end point for the memory space.
 

© University of Coimbra
Last review 1999/12