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Re: Fortran/PR19303 PATCH: Runtime selection of record markers forunformatted sequential io
- From: Bud Davis <bdavis at gfortran dot org>
- To: Janne Blomqvist <jblomqvi at cc dot hut dot fi>
- Cc: Steve Ellcey <sje at cup dot hp dot com>, Tobias Schlüter <tobias dot schlueter at physik dot uni-muenchen dot de>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, GNU GFortran <fortran at gcc dot gnu dot org>
- Date: Tue, 22 Feb 2005 21:39:41 -0600
- Subject: Re: Fortran/PR19303 PATCH: Runtime selection of record markers forunformatted sequential io
- References: <421A11EB.firstname.lastname@example.org> <200502221702.JAA11328@hpsje.cup.hp.com> <20050222210204.GA20985@vipunen.hut.fi>
On Tue, 2005-02-22 at 15:02, Janne Blomqvist wrote:
> Thanks, that was how I understood it. But the performance problem
> still remains; e.g. when writing a record the first record marker is a
> placeholder value. Presumably most records are smallish, so a single
> 32-bit number sounds reasonable. But then if the record is large, from
> where are you going to take the extra 64 bits required for the large
> record marker?
we need to calculate the size of the record to be written in the front
end prior to calling the library.
probably easier said than done.
any additional buffering eats memory and time. the memory will be
significant when someone is trying to write a 2GB array of REALS to the