Two compiler options questions:
1. Is anyone still familiar with the Large File support in Linux? My questions
are about the flags
-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
added by configure. Specifically:
a. Aren't these only needed for x86 (32-bit) compiles? Do we need them
for x86-64 (em64t)?
b. My Googling seems to indicate that only the first flag is required, not
the second one; might this be true? Does anyone have a test of this
functionality?
2. Do we really need the "-ip -O3 -xHost" flags for optimized ifort compiles?
Is this better/worse/the same as "-fast" (used for pmemd)? Does sander need
anything more than -O3? Is there a good compromise between "fastest of all
2^N possible combinations of flags on this particular machine" and "something
that sacrifices a few percent in performance but which is likely to both work
now and continue working after Intel puts out its next release"?
...thx...dac
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Received on Mon Feb 01 2010 - 12:30:02 PST
