From: Ted Dennison <dennison@telepath.com>
Subject: Re: Optimization Question
Date: Mon, 22 Jan 2001 16:48:02 GMT
Date: 2001-01-22T16:48:02+00:00 [thread overview]
Message-ID: <94ho80$pj7$1@nnrp1.deja.com> (raw)
In-Reply-To: 94hm5q$nmc$1@nnrp1.deja.com
In article <94hm5q$nmc$1@nnrp1.deja.com>,
Robert Dewar <robert_dewar@my-deja.com> wrote:
> In article <94hjbp$ks6$1@nnrp1.deja.com>,
> Ted Dennison <dennison@telepath.com> wrote:
>
> > My first iteration took the dumb approach and used Direct_IO
> > instantiated on bytes.
>
> This of course is even *WORSE* than using sequential_io, since
> there is extra positioning overhead. I can't imagine why you
> would choose Direct_IO for what is obviously a sequential
> problem. Just shows that if there is a way to abuse things
> someone will take advantage of it :-) :-)
:-)
I used Direct_IO because for my purpose (splitting the file into chunks
that will fit on the floppy), I needed to know how big the file actually
is. Direct_IO has a length-of-file routine (Size), while Sequential_IO
does not.
I suppose I could have used Direct_IO just for that purpose and
Sequential_IO for the actual IO operations. But that seemed a little
silly when Direct_IO also had all the operations I needed.
So are you saying that the versions of Read and Write in Direct_IO that
don't have the "Positive_Count" typed parameters still take longer than
the routines with the exact same parameter profile in Sequential_IO? Not
that it really matters that much. We've already ascertained that its
going to be slow either way.
--
T.E.D.
http://www.telepath.com/~dennison/Ted/TED.html
Sent via Deja.com
http://www.deja.com/
next prev parent reply other threads:[~2001-01-22 16:48 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-22 0:05 Optimization Question dvdeug
2001-01-22 1:57 ` Robert Dewar
2001-01-22 3:22 ` dvdeug
2001-01-22 4:05 ` Robert Dewar
2001-01-22 4:06 ` Robert Dewar
2001-01-22 19:04 ` M. Kotiaho
2001-01-22 20:22 ` dvdeug
2001-01-22 15:24 ` Ted Dennison
2001-01-22 16:12 ` Robert Dewar
2001-01-22 16:48 ` Ted Dennison [this message]
2001-01-22 16:15 ` Robert Dewar
2001-01-22 15:26 ` Ted Dennison
2001-01-22 16:17 ` Robert Dewar
2001-01-22 16:59 ` Ted Dennison
2001-01-22 22:01 ` Keith Thompson
2001-01-22 22:52 ` dvdeug
2001-01-23 6:46 ` Keith Thompson
[not found] ` <94ld65$1hs$1@nnrp1.deja.com>
[not found] ` <864ryodb1q.fsf@acm.org>
[not found] ` <3A6F663E.C84B94D8@acm.org>
2001-01-26 16:30 ` Optimization Question -- Follow up on using the stream read (and write) procedures directly Jeff Creem
2001-01-26 21:46 ` Florian Weimer
2001-01-27 19:14 ` Jeff Creem
2001-01-28 0:26 ` Robert Dewar
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