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Re: [Patch, gfortran]: PR21820, 23363 etc.: chuck mmap

On Sat, Sep 03, 2005 at 09:23:52PM +0300, Janne Blomqvist wrote:
> Hello,
> 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.

If we want to keep mmap (perhaps there are situations where it does
bring better performance, although my guess is not measurably so with
the current fine-grained io library), it would be relatively
straightforward to e.g. add a check for a GFORTRAN_USE_MMAP
environment variable when opening a file. That way we'd get the
performance advantages of fd while still enabling those who want mmap
to use it.

If there is some support for this alternative approach I'll retract my
patch removing mmap and implement this instead.

Janne Blomqvist

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