Installation and Configuration

./README_SMP

* * README for IBM Visualization Data Explorer for Symetric Multiprocessors * * (C) COPYRIGHT International Business Machines Corp. 1991-1997 * All Rights Reserved. * Licensed Materials - Property of IBM * * US Government Users Restricted Rights - Use, duplication or * disclosure restricted by GSA ADP Schedule Contract with IBM Corp. * * The information contained in this file consists of hints for using the Data Explorer SMP for symmetric multiprocessors. ======================================================================== CONTENTS To go directly to an item, search for the item number beginning at the left margin. 1. The Partition module 2. Partitioning an already-partitioned field 3. The default amount of memory used 4. The default number of processors used 5. The difference between SMP and distributed ======================================================================== 1. The Partition module With Data Explorer SMP, the Partition module should be used to create a composite field from the imported data. Only if the data set is partitioned will Data Explorer SMP exploit the multiple processors available. Note that you can run partitioned data equally well on both uniprocessor and multiprocessor machines. 2. Partitioning an already-partitioned field Once a field is partitioned it will not be repartitioned if it is passed through the Partition module again. Thus to maximize the use of the available processors, you may want to increase the number of partitions (the "n" paramter for Partition) from the default value if you will be operating on only a subset of the data later on. Note however, that over-partitioning a field leads to extra overhead. 3. The default amount of memory used By default on a MP machine, less memory will be used than on a UP machine. This is under the assumption that other users may be more likely to be using an MP machine. The amount of memory used can be changed with the -memory command line option to dx. Usage("memory",0) will show you how much memory is being used. 4. The default number of processors used For an MP machine, if the number of processors (n) is 4 or greater, the default number of processors used is n/2, rounded down. If the number of processors is 2 or 3, then the default number of processors used is 2. The number of processors used can be changed with the -processors command line option to dx. 5. The difference between SMP and distributed When you run parallel on an SMP machine, intramodule parallelism is used. For example, the Isosurface module will operate in parallel on different portions of a partitioned field. When you use the distributed method of execution, different modules run on different machines; for example, Isosurface might be running on one machine while MapToPlane is running on another. There is overhead involved with using distributed computation, as the data must be transferred between machines. ======================================================================== The following trademarks apply to this information: IBM is a registered trademark of International Business Machines Corporation. IBM Visualization Data Explorer is a registered trademark of International Business Machines Corporation