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Date: Tue, 6 Feb 2001 19:35:17 +0100 (CET)
From: Ingo Molnar <mingo@elte.hu>
Reply-To: <mingo@elte.hu>
To: Ben LaHaise <bcrl@redhat.com>
Cc: "Stephen C. Tweedie" <sct@redhat.com>,
        Linus Torvalds <torvalds@transmeta.com>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>,
        Manfred Spraul <manfred@colorfullife.com>, Steve Lord <lord@sgi.com>,
        Linux Kernel List <linux-kernel@vger.kernel.org>,
        <kiobuf-io-devel@lists.sourceforge.net>,
        Ingo Molnar <mingo@redhat.com>
Subject: Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait
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On Tue, 6 Feb 2001, Ben LaHaise wrote:

> > - higher levels do not have the kind of state to eg. merge requests done
> >   by different users. The only chance for merging is often the lowest
> >   level, where we already know what disk, which sector.
>
> That's what a readaround buffer is for, [...]

If you are merging based on (device, offset) values, then that's lowlevel
- and this is what we have been doing for years.

If you are merging based on (inode, offset), then it has flaws like not
being able to merge through a loopback or stacked filesystem.

	Ingo

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