From owner-freebsd-hackers  Fri Jun  1 10:15: 3 2001
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Date: Fri, 01 Jun 2001 10:15:16 -0700
From: Terry Lambert <tlambert2@mindspring.com>
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To: Peter Wemm <peter@wemm.org>
Cc: Mike Silbersack <silby@silby.com>,
	Terry Lambert <tlambert@primenet.com>, hackers@FreeBSD.ORG
Subject: Re: general speed differences between 4.1.1-RELEASE and 4.3-RELEASE
References: <20010530153842.0E221380E@overcee.netplex.com.au>
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Peter Wemm wrote:
> Terry Lambert wrote:
> > Mike Silbersack wrote:
> > > 1.  Have the ata driver leave the write cache setting
> > > alone by default, providing a sysctl which can cause
> > > disabled or enabled if requested.  When the default is
> > > allowed, put something in dmesg which says "Note: Write
> > > caching may be enabled.  See ata(4) for the reliability
> > > implications of this."
> >
> > You need to look at the code; it would be relatively hard
> > to make this runtime tunable instead of boot-time tunable.
> 
> False. It is actually very easy to change at runtime if it
> is done at a convenient time.  We have had patches kicking
> around for something like 6 months now that do this.

The patches don't (and possibly can't) do enough to ensure
a smooth transition.  Among other things, they would have
to turn off soft updates.

Please see my other post on this subject.

-- Terry

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