From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Andi Kleen <andi@firstfloor.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>,
Andi Kleen <andi@firstfloor.org>,
linux-kernel@vger.kernel.org, xfs@oss.sgi.com,
Alasdair G Kergon <agk@redhat.com>,
Andi Kleen <andi-suse@firstfloor.org>,
Milan Broz <mbroz@redhat.com>
Subject: Re: Device loses barrier support (was: Fixed patch for simple barriers.)
Date: Fri, 5 Dec 2008 11:52:25 +0000 [thread overview]
Message-ID: <20081205115225.13c277ee@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <20081205013739.GZ6703@one.firstfloor.org>
On Fri, 5 Dec 2008 02:37:39 +0100
Andi Kleen <andi@firstfloor.org> wrote:
> > * barrier support in md-raid1 deviates from the specification at
> > Documentation/block/barrier.txt. The specification says that requests
> > submitted after the barrier request hit the media after the barrier
> > request hits the media. The reality is that the barrier request can be
> > randomly aborted and the requests submitted after it hit the media before
> > the barrier request.
>
> Yes the spec should be probably updated.
>
> But also see Linus' rant from yesterday about code vs documentation.
> When in doubt the code wins.
Not when the fundamental design of the code is broken and trashes
performance. The documented behaviour is strongly desirable.
Alan
next prev parent reply other threads:[~2008-12-05 11:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.4.64.0812040009340.15169@hs20-bc2-1.build.redhat.com>
[not found] ` <20081204100050.GN6703@one.firstfloor.org>
2008-12-04 14:00 ` Mikulas Patocka
2008-12-04 14:20 ` Andi Kleen
2008-12-04 14:17 ` Mikulas Patocka
2008-12-04 14:58 ` Andi Kleen
2008-12-04 16:45 ` Mikulas Patocka
2008-12-04 17:48 ` Andi Kleen
2008-12-04 17:53 ` Christoph Hellwig
2008-12-04 19:37 ` Mikulas Patocka
2008-12-04 22:15 ` Andi Kleen
2008-12-04 23:08 ` Mikulas Patocka
2008-12-05 0:48 ` Andi Kleen
2008-12-05 1:16 ` Mikulas Patocka
2008-12-05 1:37 ` Andi Kleen
2008-12-05 2:21 ` Mikulas Patocka
2008-12-05 3:09 ` Andi Kleen
2008-12-05 11:52 ` Alan Cox [this message]
2008-12-05 12:29 ` Andi Kleen
2008-12-05 3:26 ` Device loses barrier support Eric Sandeen
2008-12-07 4:17 ` Device loses barrier support (was: Fixed patch for simple barriers.) Dave Chinner
2008-12-05 5:44 ` Device loses barrier support Timothy Shimmin
[not found] <bFnGM-7mA-5@gated-at.bofh.it>
[not found] ` <bFpyX-1jh-15@gated-at.bofh.it>
[not found] ` <bFquY-2x2-5@gated-at.bofh.it>
[not found] ` <bFsnc-51o-37@gated-at.bofh.it>
[not found] ` <bFuyC-7Zt-11@gated-at.bofh.it>
[not found] ` <bFvuI-L8-29@gated-at.bofh.it>
[not found] ` <bFwTJ-2oc-13@gated-at.bofh.it>
[not found] ` <bFxwq-3g7-1@gated-at.bofh.it>
[not found] ` <bFxGa-3pz-1@gated-at.bofh.it>
[not found] ` <bFHvW-7up-5@gated-at.bofh.it>
[not found] ` <bFHPd-84I-13@gated-at.bofh.it>
2008-12-05 18:21 ` Device loses barrier support (was: Fixed patch for simple barriers.) Bodo Eggert
2008-12-05 18:41 ` Andi Kleen
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