Xen devel - Nov 2012 - [PATCH] xl: xl.conf(5): correct advice re autoballooning vs. dom0_mem

# HG changeset patch
# User Ian Campbell <ijc@hellion.org.uk>
# Date 1354011148 0
# Node ID 3174dc24e3efb0c5b964c244dbfb0218a03a38cf
# Parent  541b0e1a36c86db5df04988dd4ade5430776a7f2
xl: xl.conf(5): correct advice re autoballooning vs. dom0_mem.

The advice was backwards, you should really disable autoballoon if you
use dom0_mem. Also add a reference to the command-line docs.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

diff -r 541b0e1a36c8 -r 3174dc24e3ef docs/man/xl.conf.pod.5
--- a/docs/man/xl.conf.pod.5	Tue Nov 27 10:05:35 2012 +0000
+++ b/docs/man/xl.conf.pod.5	Tue Nov 27 10:12:28 2012 +0000
@@ -49,9 +49,9 @@ The semantics of each C<KEY> defines whi
 
 If disabled then C<xl> will not attempt to reduce the amount of memory
 assigned to domain 0 in order to create free memory when starting a
-new domain. You should set this if you use the C<dom0_mem> hypervisor
-command line to reduce the amount of memory given to domain 0 by
-default.
+new domain. You are strongly recommended to set this to C<0>
+(C<False>) if you use the C<dom0_mem> hypervisor command line to
+reduce the amount of memory given to domain 0 by default.
 
 Default: C<1>
 
diff -r 541b0e1a36c8 -r 3174dc24e3ef docs/misc/xen-command-line.markdown
--- a/docs/misc/xen-command-line.markdown	Tue Nov 27 10:05:35 2012 +0000
+++ b/docs/misc/xen-command-line.markdown	Tue Nov 27 10:12:28 2012 +0000
@@ -440,6 +440,11 @@ reservation is unlimited.
 For example, to set dom0''s initial memory allocation to 512MB but
 allow it to balloon up as far as 1GB use `dom0_mem=512M,max:1G`
 
+If you use this option then it is highly recommended that you disable
+any dom0 autoballooning feature present in your toolstack. See the
+_xl.conf(5)_ man page or [Xen Best
+Practices](http://wiki.xen.org/wiki/Xen_Best_Practices#Xen_dom0_dedicated_memory_and_preventing_dom0_memory_ballooning).
+
 ### dom0\_shadow
 > `= <boolean>`

On Tue, 27 Nov 2012, Ian Campbell wrote:
> # HG changeset patch
> # User Ian Campbell <ijc@hellion.org.uk>
> # Date 1354011148 0
> # Node ID 3174dc24e3efb0c5b964c244dbfb0218a03a38cf
> # Parent  541b0e1a36c86db5df04988dd4ade5430776a7f2
> xl: xl.conf(5): correct advice re autoballooning vs. dom0_mem.
> 
> The advice was backwards, you should really disable autoballoon if you
> use dom0_mem. Also add a reference to the command-line docs.
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> diff -r 541b0e1a36c8 -r 3174dc24e3ef docs/man/xl.conf.pod.5
> --- a/docs/man/xl.conf.pod.5	Tue Nov 27 10:05:35 2012 +0000
> +++ b/docs/man/xl.conf.pod.5	Tue Nov 27 10:12:28 2012 +0000
> @@ -49,9 +49,9 @@ The semantics of each C<KEY> defines whi
>  
>  If disabled then C<xl> will not attempt to reduce the amount of
memory
>  assigned to domain 0 in order to create free memory when starting a
> -new domain. You should set this if you use the C<dom0_mem>
hypervisor
> -command line to reduce the amount of memory given to domain 0 by
> -default.
> +new domain. You are strongly recommended to set this to C<0>
> +(C<False>) if you use the C<dom0_mem> hypervisor command line
to
> +reduce the amount of memory given to domain 0 by default.
>  
>  Default: C<1>
>  
> diff -r 541b0e1a36c8 -r 3174dc24e3ef docs/misc/xen-command-line.markdown
> --- a/docs/misc/xen-command-line.markdown	Tue Nov 27 10:05:35 2012 +0000
> +++ b/docs/misc/xen-command-line.markdown	Tue Nov 27 10:12:28 2012 +0000
> @@ -440,6 +440,11 @@ reservation is unlimited.
>  For example, to set dom0''s initial memory allocation to 512MB but
>  allow it to balloon up as far as 1GB use `dom0_mem=512M,max:1G`
>  
> +If you use this option then it is highly recommended that you disable
> +any dom0 autoballooning feature present in your toolstack. See the
> +_xl.conf(5)_ man page or [Xen Best
>
+Practices](http://wiki.xen.org/wiki/Xen_Best_Practices#Xen_dom0_dedicated_memory_and_preventing_dom0_memory_ballooning).
> +
>  ### dom0\_shadow
>  > `= <boolean>`
>  
>

On Tue, 2012-11-27 at 11:10 +0000, Stefano Stabellini
wrote:
> On Tue, 27 Nov 2012, Ian Campbell wrote:
> > # HG changeset patch
> > # User Ian Campbell <ijc@hellion.org.uk>
> > # Date 1354011148 0
> > # Node ID 3174dc24e3efb0c5b964c244dbfb0218a03a38cf
> > # Parent  541b0e1a36c86db5df04988dd4ade5430776a7f2
> > xl: xl.conf(5): correct advice re autoballooning vs. dom0_mem.
> > 
> > The advice was backwards, you should really disable autoballoon if you
> > use dom0_mem. Also add a reference to the command-line docs.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> 
> 
> Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Applied, thanks.

Ian Campbell writes ("[PATCH] xl: xl.conf(5): correct advice re
autoballooning vs. dom0_mem"):
> xl: xl.conf(5): correct advice re autoballooning vs. dom0_mem.
> 
> The advice was backwards, you should really disable autoballoon if you
> use dom0_mem. Also add a reference to the command-line docs.
Thanks.  This seemed worth a backport so I''ve thrown it into 4.2.

Ian.