Xen users - Oct 2006 - Problem for "xm create": "kernel: Setting mem allocation to ..."

Hi,

When trying to boot a freshly created VM, nothing seems to happen, but Dom0 
repeats  messages like
kernel: Setting mem allocation to ... kIB
while "..." is some large number like this:
Oct 19 15:55:33 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
Oct 19 15:55:41 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
Oct 19 15:55:46 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
Oct 19 15:55:54 rkdvmso1 kernel: Setting mem allocation to 816764 kiB

Eventually I see (after "xm create"):
Error: The privileged domain did not balloon!

Now I think the error message on the console and in the syslog could be
improved:
Is Dom0 kernel retrying, how much is available (I assume less than demanded).
Could this be a NUMA problem?

A "# xm mem-set 0 256" to reduce the mem of Domain-0, but the VM
wouldn''t start,
and Domain-0 re-allocated the previous size (556M)

How do I limit the maximum mem for Domain-0, so that DomUs have enough RAM left 
over for them?

Regards,
Ulrich


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there is a balloon setting to specify the ram usage by Dom0, look in your
/etc/xend-config.sxp near the end of the file.
Your error msg indicates there is not enough free ram.

You can check it with xm list, that will show the current mem usage with
Xen. Free -h will show system mem usage.

On 10/19/06, Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>
wrote:
>
> Hi,
>
> When trying to boot a freshly created VM, nothing seems to happen, but
> Dom0
> repeats  messages like
> kernel: Setting mem allocation to ... kIB
> while "..." is some large number like this:
> Oct 19 15:55:33 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
> Oct 19 15:55:41 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
> Oct 19 15:55:46 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
> Oct 19 15:55:54 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
>
> Eventually I see (after "xm create"):
> Error: The privileged domain did not balloon!
>
> Now I think the error message on the console and in the syslog could be
> improved:
> Is Dom0 kernel retrying, how much is available (I assume less than
> demanded).
> Could this be a NUMA problem?
>
> A "# xm mem-set 0 256" to reduce the mem of Domain-0, but the VM
wouldn''t
> start,
> and Domain-0 re-allocated the previous size (556M)
>
> How do I limit the maximum mem for Domain-0, so that DomUs have enough RAM
> left
> over for them?
>
> Regards,
> Ulrich
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>

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On 19 Oct 2006 at 16:48, harm wrote:
> there is a balloon setting to specify the ram usage by Dom0, look in your
> /etc/xend-config.sxp near the end of the file.
Not here (SLES10): I only have:
# Dom0 will balloon out when needed to free memory for domU.
# dom0-min-mem is the lowest memory level (in MB) dom0 will get down to.
# If dom0-min-mem=0, dom0 will never balloon out.
(dom0-min-mem 196)

> Your error msg indicates there is not enough free ram.
not very clearly, and I wonder why it takes about one minute to find out that 
there''s not enough  RAM.
> 
> You can check it with xm list, that will show the current mem usage with
> Xen. Free -h will show system mem usage.
# free -h
free: invalid option -- h
[...]

Ulrich
> 
> On 10/19/06, Ulrich Windl <ulrich.windl@rz.uni-regensburg.de> wrote:
> >
> > Hi,
> >
> > When trying to boot a freshly created VM, nothing seems to happen, but
> > Dom0
> > repeats  messages like
> > kernel: Setting mem allocation to ... kIB
> > while "..." is some large number like this:
> > Oct 19 15:55:33 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
> > Oct 19 15:55:41 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
> > Oct 19 15:55:46 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
> > Oct 19 15:55:54 rkdvmso1 kernel: Setting mem allocation to 816764 kiB
> >
> > Eventually I see (after "xm create"):
> > Error: The privileged domain did not balloon!
> >
> > Now I think the error message on the console and in the syslog could
be
> > improved:
> > Is Dom0 kernel retrying, how much is available (I assume less than
> > demanded).
> > Could this be a NUMA problem?
> >
> > A "# xm mem-set 0 256" to reduce the mem of Domain-0, but
the VM wouldn''t
> > start,
> > and Domain-0 re-allocated the previous size (556M)
> >
> > How do I limit the maximum mem for Domain-0, so that DomUs have enough
RAM
> > left
> > over for them?
> >
> > Regards,
> > Ulrich
> >
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@lists.xensource.com
> > http://lists.xensource.com/xen-users
> >
> 


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Am Freitag, 20. Oktober 2006 08:36 schrieb Ulrich Windl:
> On 19 Oct 2006 at 16:48, harm wrote:
> > there is a balloon setting to specify the ram usage by Dom0, look in
your
> > /etc/xend-config.sxp near the end of the file.
>
> Not here (SLES10): I only have:
> # Dom0 will balloon out when needed to free memory for domU.
> # dom0-min-mem is the lowest memory level (in MB) dom0 will get down to.
> # If dom0-min-mem=0, dom0 will never balloon out.
> (dom0-min-mem 196)
>
> > Your error msg indicates there is not enough free ram.
>
> not very clearly, and I wonder why it takes about one minute to find out
> that there''s not enough  RAM.
>
> > You can check it with xm list, that will show the current mem usage
with
> > Xen. Free -h will show system mem usage.
>
> # free -h
> free: invalid option -- h
free -m natürlich ^^ 

lg
stephan
> [...]
>
> Ulrich
>
> > On 10/19/06, Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>
wrote:
> > > Hi,
> > >
> > > When trying to boot a freshly created VM, nothing seems to
happen, but
> > > Dom0
> > > repeats  messages like
> > > kernel: Setting mem allocation to ... kIB
> > > while "..." is some large number like this:
> > > Oct 19 15:55:33 rkdvmso1 kernel: Setting mem allocation to 816764
kiB
> > > Oct 19 15:55:41 rkdvmso1 kernel: Setting mem allocation to 816764
kiB
> > > Oct 19 15:55:46 rkdvmso1 kernel: Setting mem allocation to 816764
kiB
> > > Oct 19 15:55:54 rkdvmso1 kernel: Setting mem allocation to 816764
kiB
> > >
> > > Eventually I see (after "xm create"):
> > > Error: The privileged domain did not balloon!
> > >
> > > Now I think the error message on the console and in the syslog
could be
> > > improved:
> > > Is Dom0 kernel retrying, how much is available (I assume less
than
> > > demanded).
> > > Could this be a NUMA problem?
> > >
> > > A "# xm mem-set 0 256" to reduce the mem of Domain-0,
but the VM
> > > wouldn''t start,
> > > and Domain-0 re-allocated the previous size (556M)
> > >
> > > How do I limit the maximum mem for Domain-0, so that DomUs have
enough
> > > RAM left
> > > over for them?
> > >
> > > Regards,
> > > Ulrich
> > >
> > >
> > > _______________________________________________
> > > Xen-users mailing list
> > > Xen-users@lists.xensource.com
> > > http://lists.xensource.com/xen-users
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
-- 
Stephan Augustin
Rosenpark 3
65795 Hattersheim
06190/879166
0173/1735867

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> > there is a balloon setting to specify the ram usage by Dom0, look in
your
> > /etc/xend-config.sxp near the end of the file.
>
> Not here (SLES10): I only have:
> # Dom0 will balloon out when needed to free memory for domU.
> # dom0-min-mem is the lowest memory level (in MB) dom0 will get down to.
> # If dom0-min-mem=0, dom0 will never balloon out.
> (dom0-min-mem 196)
That''s the one you''ll want to tweak if you''re using
autoballooning to reduce
dom0 when creating other domains (as opposed to statically choosing
dom0''s
size at boot time / or ballooning dom0 manually with xm mem-set).
> > Your error msg indicates there is not enough free ram.
>
> not very clearly, and I wonder why it takes about one minute to find out
> that there''s not enough  RAM.
Some of the error messages aren''t very clear :-/
> > You can check it with xm list, that will show the current mem usage
with
> > Xen. Free -h will show system mem usage.
>
> # free -h
> free: invalid option -- h
> [...]
Now this is something I *always* get wrong myself.

I think the OP meant to say "free -m" for free space in megabytes. 
It''s easy
to muddle this up with the "df -h" command for "free disk space,
human
readable (i.e. megabytes) - I confuse the two very frequently.

"xm info" will tell you about the free memory in the system, from
Xen''s PoV
(i.e. what you have available for domain creation)

Cheers,
Mark
> Ulrich
>
> > On 10/19/06, Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>
wrote:
> > > Hi,
> > >
> > > When trying to boot a freshly created VM, nothing seems to
happen, but
> > > Dom0
> > > repeats  messages like
> > > kernel: Setting mem allocation to ... kIB
> > > while "..." is some large number like this:
> > > Oct 19 15:55:33 rkdvmso1 kernel: Setting mem allocation to 816764
kiB
> > > Oct 19 15:55:41 rkdvmso1 kernel: Setting mem allocation to 816764
kiB
> > > Oct 19 15:55:46 rkdvmso1 kernel: Setting mem allocation to 816764
kiB
> > > Oct 19 15:55:54 rkdvmso1 kernel: Setting mem allocation to 816764
kiB
> > >
> > > Eventually I see (after "xm create"):
> > > Error: The privileged domain did not balloon!
> > >
> > > Now I think the error message on the console and in the syslog
could be
> > > improved:
> > > Is Dom0 kernel retrying, how much is available (I assume less
than
> > > demanded).
> > > Could this be a NUMA problem?
> > >
> > > A "# xm mem-set 0 256" to reduce the mem of Domain-0,
but the VM
> > > wouldn''t start,
> > > and Domain-0 re-allocated the previous size (556M)
> > >
> > > How do I limit the maximum mem for Domain-0, so that DomUs have
enough
> > > RAM left
> > > over for them?
> > >
> > > Regards,
> > > Ulrich
> > >
> > >
> > > _______________________________________________
> > > Xen-users mailing list
> > > Xen-users@lists.xensource.com
> > > http://lists.xensource.com/xen-users
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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