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Re: [PATCH] Re: tmem on 4.1 (was [Xen-devel] Re: Freeze schedule)

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Subject: Re: [PATCH] Re: tmem on 4.1 (was [Xen-devel] Re: Freeze schedule)
From: "Olivier B." <xen.list@xxxxxxxxx>
Date: Thu, 20 Jan 2011 09:07:47 +0100
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Le 20/01/2011 08:17, Keir Fraser a écrit :
On 19/01/2011 21:38, "Dan Magenheimer"<dan.magenheimer@xxxxxxxxxx>  wrote:

Just to check again, has anyone actually seen a problem with
tmem enabled by default recently?  I agree that there is still
theoretically a problem, but there is the same problem with
normal guests doing lots of ballooning as well.  Also, note
that even if tmem defaults to enabled, the problem is impossible
unless a guest enables tmem (or, in the case of SuSE, dom0).
And even if a guest does enable tmem, the problem manifested
largely due to shadow pages using order>0 (now fixed?)...
failure on domain creation can happen for many reasons and
is much less of an issue, true?

Feel free to shoot me down with more evidence, but I have
to at least provide token resistance to this patch.  Distros
might certainly choose to disable it to avoid any risk at
all, but turning it off anymore seems overkill for xen.org
open source Xen IMHO.

Tbh I was wondering whether anyone is really using it in earnest. No
upstream kernels support it? If noone's using it, who really cares whether
it's enabled or not, apart from its author.

  -- Keir

Well, it is present but disabled in the new Debian Squeeze kernel... and as there is no documentation, there is no chance to see it enabled.

I had to search on the xen lists to find how to enable that.

For example :

We should maybe add info about tmem on the Xen Wiki, no ?


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