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configure test for a mmap flag
- From: Steve Kargl <sgk at troutmask dot apl dot washington dot edu>
- To: gcc at gcc dot gnu dot org
- Date: Mon, 30 May 2005 14:10:23 -0700
- Subject: configure test for a mmap flag
gfortran uses mmap for its IO if an OS has mmap. If
found, mmap is used with the MAP_SHARED flag. On linux
(and other OS's) this seems to be okay, but on FreeBSD
IO can significantly degrade if a file pre-exists. In
some testing I've done, linux's MAP_SHARED appears to be
equivalent to FreeBSD's (MAP_SHARED | MAP_NOSYNC). I
need to add a configure test to determine if MAP_NOSYNC
is present. I haven't found an example in the gcc/
directory hierarachy on how this might be accomplished.
Any pointers?
--
Steve