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Date: Thu, 27 Mar 2003 09:39:18 -0800
From: Alfred Perlstein <bright@mu.org>
To: Eivind Eklund <eivind@FreeBSD.org>
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cc: cvs-src@FreeBSD.org
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cc: Tor Egge <tegge@FreeBSD.org>
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Subject: Re: cvs commit: src/sys/conf NOTES files options src/sys/kern
	vfs_bio.c src/sys/ufs/ffs ffs_rawread.c ffs_vnops.c
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* Eivind Eklund <eivind@FreeBSD.org> [030327 03:16] wrote:
> On Wed, Mar 26, 2003 at 03:40:42PM -0800, Tor Egge wrote:
> > tegge       2003/03/26 15:40:42 PST
> > 
> >   FreeBSD src repository
> > 
> >   Modified files:
> >     sys/conf             NOTES files options 
> >     sys/kern             vfs_bio.c 
> >     sys/ufs/ffs          ffs_vnops.c 
> >   Added files:
> >     sys/ufs/ffs          ffs_rawread.c 
> >   Log:
> >   Add support for reading directly from file to userland buffer when the
> >   O_DIRECT descriptor status flag is set and both offset and length is a
> >   multiple of the physical media sector size.
> 
> Why only in the O_DIRECT case?  O_DIRECT is normally used to avoid caching
> effects *in order to avoid side effects of caching*, at the cost of speed.
> This patch seems to do the opposite - speed up the codepath significantly.
> 
> Not that it isn't nice - it would just be even nicer to have available some
> way to just say "max speed, please".

Actually this is what O_DIRECT was intended to be as soon as someone
got around to it.  I initially thought it would be dillon, but tegge
was a pleasant suprise.  :)

-- 
-Alfred Perlstein [alfred@freebsd.org]
'Instead of asking why a piece of software is using "1970s technology,"
 start asking why software is ignoring 30 years of accumulated wisdom.'