Subject: Re: RAW access to files
To: None <email@example.com>
From: Magnus Enbom <firstname.lastname@example.org>
Date: 12/11/2001 15:15:13
On Tue, Dec 11, 2001 at 07:36:55AM -0500, email@example.com wrote:
> > On Mon, Dec 10, 2001 at 07:42:07PM +0100, Wojciech Puchar wrote:
> > > > this is more often called "direct i/o" or "unbuffered i/o".
> > > > it's on the list of things I want to add, but I haven't had time yet.
> > >
> > > it would be really good! with support in common mpeg/divx players etc..
> > > and with option in cp and dd
> > Why do you think that "raw" I/O would be more efficient than the
> > filesystem buffer cache doing readahead?
> > -is
> As an interresting side point, I've heard rumors that Solaris 9 will
> include a "direct I/O" feature in UFS. For what [good] reasons, I'm not
> sure, but I'm sure there have to be valid reasons...
It's been in Solaris since at least 2.6. mount -o forcedirectio does the
trick. You can also tune it on filebasis via the stickybit, just chmod +t your
files and they will bypass the buffercache. That's a common trick to do when
tuning database systems.