From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Jens Axboe <axboe@suse.de>
Cc: Arjan van de Ven <arjanv@redhat.com>,
Neil Brown <neilb@cse.unsw.edu.au>,
Christoph Hellwig <hch@lst.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: bug in md write barrier support?
Date: Thu, 09 Sep 2004 13:51:14 +0100 [thread overview]
Message-ID: <1094734272.14623.2.camel@localhost.localdomain> (raw)
In-Reply-To: <20040909082922.GN1737@suse.de>
On Iau, 2004-09-09 at 09:29, Jens Axboe wrote:
> > why does this seem broken? semantics of "cache flush guarantees that all
> > io submitted prior to it hits the spindle" are quite sane imo; no
> > guarantee of later submitted IO.. compare the unix "sync" command; same
> > level of semantics.
>
> Depends on your angle, I think it breaks the principle of least
> surprise.
As far as I can ascertain raid controllers in general follow this set of
semantics. Its less of an issue for many of them with battery backup
obviously.
It also makes a lot of sense at the hardware level for performance
especially when dealing with raid.
Alan
next prev parent reply other threads:[~2004-09-09 13:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-03 17:24 bug in md write barrier support? Christoph Hellwig
2004-09-04 0:56 ` Neil Brown
2004-09-04 8:21 ` Jens Axboe
2004-09-06 1:36 ` Neil Brown
2004-09-08 9:23 ` Jens Axboe
2004-09-08 13:35 ` Alan Cox
2004-09-08 15:46 ` Jens Axboe
2004-09-08 22:21 ` Alan Cox
2004-09-09 8:06 ` Jens Axboe
2004-09-09 8:22 ` Arjan van de Ven
2004-09-09 8:29 ` Jens Axboe
2004-09-09 12:51 ` Alan Cox [this message]
2004-09-09 14:34 ` Jens Axboe
2004-09-12 17:13 ` Rogier Wolff
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