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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: Journaling pointless with today's hard disks?
Date: 26 Nov 2001 16:52:52 -0800
Organization: Transmeta Corporation, Santa Clara CA
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Followup to:  <9tumf0$dvr$1@cesium.transmeta.com>
By author:    "H. Peter Anvin" <hpa@zytor.com>
In newsgroup: linux.dev.kernel
> 
> Indeed; having explicit write barriers would be a very useful feature,
> but the drives MUST default to strict ordering unless reordering (with
> write barriers) have been enabled explicitly by the OS.
> 

On the subject of write barriers... such a setup probably should have
a serial number field for each write barrier command, and a "WAIT FOR
WRITE BARRIER NUMBER #" command -- which will wait until all writes
preceeding the specified write barrier has been committed to stable
storage.  It might also be worthwhile to have the equivalent
nonblocking operation -- QUERY LAST WRITE BARRIER COMMITTED.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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