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Find & Replacement & Delete

Posted January 19, 2012 at 12:13 by lakeat (Daniel Wei's CFD Blog: (http://lakeat.co.nf/))

Here are some tips, to show that linux is really very powerful, once you know how to use it.

Example-1
If you want to find or replacement, you dont need to open an editor, gedit, or vi. You can just simply do the following (choose one).
Why not just vi and :%s....? Because, the following command can be implemented in a shell scripts, so once you have dozens of files to operate, this is the better way.

perl -e "s/old_string/new_string/g"
...
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Old

Dark side of Amdahl's law. Epilogue

Posted January 12, 2012 at 11:03 by SergeAS
Updated January 13, 2012 at 08:32 by SergeAS

Dependence of efficiency on the number of cores is a very important characteristic of scalability solver based on which one can predict the scaling limit. For simplicity we consider only one option for the solver, using the asynchronous version of the MPI exchanges Isend() + Irecv(). It is seen that the dependence of the efficiency of parallelization of the solver is linear or nearly linear, with a gradual drop in effectivity with increasing number of cores used
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Running OpenFOAM in parallel with different locations for each process

Posted December 15, 2011 at 17:56 by wyldckat

The other day a fellow forum user asked me for help about a problem dealing with the specific configuration of a case for running in a cluster. The specific configuration was simple: each slave machine of the cluster has it's own independent storage address on a similar path.
Below is an edited version of the reply I sent him.


OK, first detail - In the following file you have a (sort-of) well documented "decomposeParDict":
Code:
applications/utilities/parallelProcessing/decomposePar/decomposeParDict
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Old

Dark side of Amdahl's law. Part III

Posted December 9, 2011 at 12:04 by SergeAS
Tags mpi, parallel

...use a blocking call Sendrecv() instead of a pair of Send() + Recv() slightly improves the performance of the code but does not result to improved scalability


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Dark side of Amdahl's law. Part II

Posted December 4, 2011 at 10:57 by SergeAS
Updated December 4, 2011 at 11:44 by SergeAS
Tags mpi, parallel

Let us consider in more detail how works domain decomposition in the simplest 1D case.
The computational domain is divided into several subdomains along one (usually the longest) dimension. The number of such subdomains usually corresponds to the number cores involved. The main data exchanges take place between neighboring subdomains. The size of transmitted data between adjacent subdomains in the general case depends on many factors (number of equations in the system, the size of the computational...
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