From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
Marek Marczykowski <marmarek@mimuw.edu.pl>
Subject: Re: blkfront problem in pvops kernel when barriers enabled
Date: Wed, 07 Sep 2011 10:34:49 -0700 [thread overview]
Message-ID: <4E67AB39.70801@goop.org> (raw)
In-Reply-To: <20110907014741.GD30639@dumpdata.com>
On 09/06/2011 06:47 PM, Konrad Rzeszutek Wilk wrote:
> (on 3.1rc2) Looking to xenstore now there is 'feature-flush-cache=1' and
> no 'feature-barrier'. So it is ok.
> <scratches head>
>
> I can only think of 2.6.38-3 XenOLinux doing it - and it is a bug
> to do it. It really ought to _not_ advertise 'feature-barrier' and
> instead advertise 'feature-flush-cache'.
Does that mean that older guests which don't understand flush-cache will
be left with no way to force writes to stable storage? Seems to me that
even if the backend would prefer flush-cache, it should also advertise
barriers.
However, that raises the question of how to express the preferred
mechanism if multiple are available. You could assume that flush-cache
is always preferred if available, but that's pretty clunky.
J
next prev parent reply other threads:[~2011-09-07 17:34 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-04 10:49 blkfront problem in pvops kernel when barriers enabled Marek Marczykowski
2011-09-06 16:32 ` Konrad Rzeszutek Wilk
2011-09-06 16:55 ` Konrad Rzeszutek Wilk
2011-09-06 17:47 ` Marek Marczykowski
2011-09-06 17:16 ` Marek Marczykowski
2011-09-07 1:47 ` Konrad Rzeszutek Wilk
2011-09-07 9:50 ` Jan Beulich
2011-09-07 10:19 ` Jan Beulich
2011-09-07 17:41 ` Konrad Rzeszutek Wilk
2011-09-08 8:06 ` Jan Beulich
2011-09-08 13:11 ` Konrad Rzeszutek Wilk
2011-09-07 17:34 ` Jeremy Fitzhardinge [this message]
2011-09-07 17:43 ` Konrad Rzeszutek Wilk
2011-09-07 18:58 ` Jeremy Fitzhardinge
2011-09-07 19:31 ` Konrad Rzeszutek Wilk
2011-12-01 19:08 ` Konrad Rzeszutek Wilk
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