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From: dvdeug@my-deja.com
Newsgroups: comp.lang.ada
Subject: Re: Optimization Question
Date: Mon, 22 Jan 2001 03:22:44 GMT
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Date: 2001-01-22T03:22:44+00:00
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In article <94g431$ge3$1@nnrp1.deja.com>,
  Robert Dewar <robert_dewar@my-deja.com> wrote:
> In article <94ftfu$b59$1@nnrp1.deja.com>,
>   dvdeug@my-deja.com wrote:
>
> <<questions about speeding up code snipped>>
>
> I am *amazed* that this is only ten times slower when the
> I/O is done in such a perfectly gruesome manner (sequential
> I/O instantiated on bytes).
>
> It is elementary that you want to read big chunks of a file
> at a time. What GNAT does is to read the entire source of
> a program in one read statement.

Actually, it's only about 3-5 times slower, after doing more careful
measurements. I think GNU strings might be too wrapped up in the details
of object code to be a good general purpose strings program.

Unfortunately, that "perfectly gruesome manner" is the only one that
jumps out at me. I don't want to use Ada.Text_IO, because I want control
of CR's and LF's. I don't see how to use Sequential I/O on larger
chunks, as I may end up with a piece of file that doesn't fill a chunk.
Direct I/O can't be faster than sequential I/O. And reading a 17GB file
into memory doesn't seem like a good idea.

--
David Starner - dstarner98@aasaa.ofe.org


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