Date: Fri, 20 Aug 1999 18:57:38 +0800 From: Peter Wemm <peter@netplex.com.au> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Peter Jeremy <jeremyp@gsmx07.alcatel.com.au>, julian@whistle.com, cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org, grog@lemis.com Subject: Re: Splitting struct buf Message-ID: <19990820105738.8D3271C1F@overcee.netplex.com.au> In-Reply-To: Your message of "Fri, 20 Aug 1999 07:01:45 %2B0200." <2046.935125305@critter.freebsd.dk>
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Poul-Henning Kamp wrote:
> In message <99Aug20.101641est.40337@border.alcanet.com.au>, Peter Jeremy writ
es:
> >Julian Elischer <julian@whistle.com> wrote:
> >>changing both is also a fair idea.
> >>(that way we know that someone looked at ALL the places the present struct
> >>buf is used.. :-)
> >
> >Ignoring the smiley, I think this is probably the best suggestion. It
> >provides a clear `heads-up' for any independent device writers that
> >the usage has changed. There are about 750 references to struct buf
> >in the kernel - missing one would be quite easy.
> >
> >If only one name changes, then POLA would suggest that `struct buf'
> >remain associated with I/O requests (which is the historical and
> >probably most common usage).
>
> I'm happy either way, I'm not religiously attached to any of the
> names.
For what it's worth, given all the options, I'd prefer that we gutted all
the caching aspects from 'struct buf' and rename the caching part to
something else. The reason being, the impact of the caching part is confined
to source that we control and maintain, while the IO part is very heavily
exposed to the device drivers. I don't think we gain much by turning the
device driver interface totally on it's head and making it harder still to
port drivers (not only relative to other unixen, but older freebsd versions
too).
Of course, there are other options too, but if we can avoid making driver
portability 10 times harder without making it too inconvenient for us, I
think it's worth doing.
Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
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