* configure test for a mmap flag
@ 2005-05-30 23:28 Steve Kargl
2005-05-30 23:44 ` Florian Weimer
0 siblings, 1 reply; 3+ messages in thread
From: Steve Kargl @ 2005-05-30 23:28 UTC (permalink / raw)
To: gcc
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: configure test for a mmap flag
2005-05-30 23:28 configure test for a mmap flag Steve Kargl
@ 2005-05-30 23:44 ` Florian Weimer
2005-05-31 2:47 ` Steve Kargl
0 siblings, 1 reply; 3+ messages in thread
From: Florian Weimer @ 2005-05-30 23:44 UTC (permalink / raw)
To: Steve Kargl; +Cc: gcc
* Steve Kargl:
> I need to add a configure test to determine if MAP_NOSYNC is
> present.
What about "#ifdef MAP_NOSYNC" in the code? Or do you invoke mmap
directly from Fortran?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: configure test for a mmap flag
2005-05-30 23:44 ` Florian Weimer
@ 2005-05-31 2:47 ` Steve Kargl
0 siblings, 0 replies; 3+ messages in thread
From: Steve Kargl @ 2005-05-31 2:47 UTC (permalink / raw)
To: Florian Weimer; +Cc: gcc
On Mon, May 30, 2005 at 11:17:34PM +0200, Florian Weimer wrote:
> * Steve Kargl:
>
> > I need to add a configure test to determine if MAP_NOSYNC is
> > present.
>
> What about "#ifdef MAP_NOSYNC" in the code? Or do you invoke mmap
> directly from Fortran?
There are sometimes too many TREEs (pun intended :-)
to see the forest.
--
Steve
^ permalink raw reply [flat|nested] 3+ messages in thread
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2005-05-30 23:28 configure test for a mmap flag Steve Kargl
2005-05-30 23:44 ` Florian Weimer
2005-05-31 2:47 ` Steve Kargl
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