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From: Christoph Hellwig <hch@infradead.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	jbeulich@novell.com, linux-kernel@vger.kernel.org,
	JBeulich@suse.com
Subject: Re: Help with implementing some form of barriers in 3.0 kernels.
Date: Thu, 8 Sep 2011 04:22:29 -0400	[thread overview]
Message-ID: <20110908082229.GB14549@infradead.org> (raw)
In-Reply-To: <20110907213137.GJ31726@redhat.com>

On Wed, Sep 07, 2011 at 05:31:37PM -0400, Vivek Goyal wrote:
> I have a basic question. In old guest why BARRIER handling on request
> queue is not sufficient for sequencing and ordering of requests and why
> xen-blkfront and qemu have to do something about it.
> 
> I am also wondering if virtio-blk have similar issues?

Mainline xen-blkfront was using ORDERED_TAG before, which meant
bypassing the sequencer entirely, as well as not beeing able to
implement plain cache flushes as used by ->fsync.


  reply	other threads:[~2011-09-08  8:22 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-07 17:48 Konrad Rzeszutek Wilk
2011-09-07 18:17 ` Vivek Goyal
2011-09-07 18:27   ` Konrad Rzeszutek Wilk
2011-09-07 18:36     ` Vivek Goyal
2011-09-07 20:16   ` Christoph Hellwig
2011-09-07 21:31     ` Vivek Goyal
2011-09-08  8:22       ` Christoph Hellwig [this message]
2011-09-08  8:02     ` Jan Beulich
2011-09-08  8:08       ` Christoph Hellwig
2011-09-13 10:44 ` Jan Beulich
2011-09-14  8:59   ` Konrad Rzeszutek Wilk
2011-09-14  9:12     ` Jan Beulich
2011-09-14  9:30       ` Konrad Rzeszutek Wilk
2011-09-14 10:15         ` Jan Beulich
2011-09-14 14:32       ` Konrad Rzeszutek Wilk
2011-09-14 15:01         ` [PATCH]: xen/blkback: Add support for old BARRIER requests - 'feature-barrier', was "Help with implementing some form of barriers in 3.0 kernels." Konrad Rzeszutek Wilk
2011-09-14 16:13           ` Jan Beulich
2011-09-15 12:51             ` Konrad Rzeszutek Wilk
2011-09-15 13:00               ` Jan Beulich
2011-09-15 14:21                 ` Konrad Rzeszutek Wilk
2011-09-15 15:13                   ` Jan Kara
2011-09-15 15:15                     ` Christoph Hellwig
2011-09-16  9:24                       ` Konrad Rzeszutek Wilk
2011-09-15 13:24             ` Jan Kara
2011-09-14 15:34         ` Help with implementing some form of barriers in 3.0 kernels Mike Snitzer

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