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Date: Thu, 10 Oct 2002 13:50:43 -0400
From: Mark Mielke <mark@mark.mielke.cc>
To: Helge Hafting <helgehaf@aitel.hist.no>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] O_STREAMING - flag for optimal streaming I/O
Message-ID: <20021010175043.GA16962@mark.mielke.cc>
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On Thu, Oct 10, 2002 at 12:55:08PM +0200, Helge Hafting wrote:
> Mark Mielke wrote:
> > I might be wrong, but it seems to me that O_STREAMING isn't the answer
> > to everything. The primary benefactors of O_STREAMING would be
> > applications that read very large files that do not fit into RAM, from
> > start to finish.
> It don't have to be a file that don't fit into RAM.  Remember, other
> running apps wants memory and cache too, so the "fair share" of memory
> for _this_ process is much smaller than all of RAM.
> So, O_STREAMING makes sense for all files where we know that we're going
> sequentially and that caching this for long won't help. 
> (Because the contents likely will be pushed out before we need
> them again anyway (DVD case) or we know were going to delete
> the file, or we simply don't want to push anything else
> out even if we could cache this.)

Then perhaps O_STREAMING should be called O_EXTENDEDSTREAMING.

If you overload O_STREAMING to contain all possibile uses for sequential
reads, you end up hurting yourself.

Small files are different beasts from large files. If you want O_STREAMING
to work in all cases, you really want standard mode to work in all cases,
and O_STREAMING is not for you.

mark

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