Difference: FortranBase64 (3 vs. 4)

Revision 413 Jun 2006 - FawziMohamed

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Fortran 90 base64 encoding of Reals

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 In the directory there is a fortran file for the tool (convertBase64.F90) and also some supporting files to test it, in particular the python script =testBase64.F90. If you have problems on some architectures/compilers try running it to pinpoint the problem.

I think that the code is close to optimal from the feature point of view.



What are the problems
-- FawziMohamed - 24 May 2006


Unfortunately in all the compilers that I came across formatted write/read is much less optimized than binary, and sting handling is not efficient. Base64 is faster than a formatted write, but slower than binary. If formatted write was an option, base64 is a clear winner, but if you need top performance writing to a local disk then it might not be for you.


Done with an older version, the actual version is 10-20% faster for base64. Reading is similar. Opteron writing to a local disk:

20x1e6 reals:
intel, binary: 0.17s total, 20x7.8MB
intel, base64: 6.54s total, 38% strcopy, 48% write, 20x10.4MB
intel formatted write: 37.7s total, 78% in sys calls (write whole array at once) 20x34MB

20x1e7 reals:
intel, binary 1.5s total, all in system calls, 20x78MB
intel, base64 71s total, 34% strcopy, 45% formatted write (530 characters at once) 20x104MB
intel, formatted write 364s total, 78% in systems calls (write whole array at once) 20x346MB

20x1e8 reals:
intel, binary 16.4s total , (31s elapsed), all in system calls 20x782MB
intel, base64 650s total, 47% formatted write, 32% strcopy , 20x 1047MB
intel formatted not done

-- FawziMohamed - 13 Jun 2006

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