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Re: [Patch, gfortran]: PR21820, 23363 etc.: chuck mmap
- From: Tobias Schlüter <tobias dot schlueter at physik dot uni-muenchen dot de>
- To: Janne Blomqvist <jblomqvi at cc dot hut dot fi>
- Cc: GNU GFortran <fortran at gcc dot gnu dot org>,GCC patches <gcc-patches at gcc dot gnu dot org>
- Date: Sat, 03 Sep 2005 20:56:43 +0200
- Subject: Re: [Patch, gfortran]: PR21820, 23363 etc.: chuck mmap
- References: <20050903182352.GA19706@vipunen.hut.fi>
Janne Blomqvist wrote:
> the attached patch provides a partial fix for the performance issues
> in PR 21820 and 23363. Partial, as in improving performance 20-fold
> for some cases but still being far away from other compilers. The
> patch also solves all mmap related correctness problems, by removing
> mmap support from the runtime library.
The comment at the beginning of unix.c should then be removed as well:
/* This implementation of stream I/O is based on the paper:
*
* "Exploiting the advantages of mapped files for stream I/O",
* O. Krieger, M. Stumm and R. Umrau, "Proceedings of the 1992 Winter
* USENIX conference", p. 27-42.
*
* It differs in a number of ways from the version described in the
* paper. First of all, threads are not an issue during I/O and we
* also don't have to worry about having multiple regions, since
* fortran's I/O model only allows you to be one place at a time.
...
I don't know enough about this stuff to say if this patch is a good thing or
not, the patch itself probably falls under the trivial rule, once it is agreed
that this is a good thing.
- Tobi