Re: [Xen-devel] libxl: error: libxl.c:2150:libxl_set_memory_target new target 0 for dom0 is below the minimum threshold

[Teck Choon Giam <giamteckchoon@xxxxxxxxx>]

On Tue, Nov 22, 2011 at 5:09 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Tue, 2011-11-22 at 08:38 +0000, Teck Choon Giam wrote:
>> On Tue, Nov 22, 2011 at 4:31 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> 
>> wrote:
>> > On Tue, 2011-11-22 at 08:30 +0000, Teck Choon Giam wrote:
>> >> On Tue, Nov 22, 2011 at 4:18 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> 
>> >> wrote:
>> >> > On Tue, 2011-11-22 at 07:56 +0000, Teck Choon Giam wrote:
>> >> > [...]
>> >> >> memory = 15360
>> >> >> maxmem = 15360
>> >> > [...]
>> >> >> How much RAM does the host system have? What are your hypervisor and
>> >> >> > dom0 command lines.
>> >> >>
>> >> >> 16GB RAM.
>> >> >
>> >> > So you are assigning 15GB out of a total of 16GB to the guest which
>> >> > necessitates ballooning dom0 from 16GB down to 1GB.
>> >>
>> >> I actually set dom0-min-mem 512 in xend-config.sxp as well.
>> >
>> > xl/libxl don't use this configuration file.
>>
>> Oh... now then I know.  I always test with both xl and xm for my
>> testing machine(s) to see any differences as there are... ...
>
> I believe xend and xl do behave slightly differently wrt dom0 auto
> ballooning.
>
>>
>> >
>> >>
>> >> >
>> >> >> title Scientific Linux (2.6.32.47-0.xen.pvops.choon.sl6)
>> >> >>       root (hd0,0)
>> >> >>       kernel /xen.gz dom0_mem=512M loglvl=all guest_loglvl=all 
>> >> >> cpuidle=0 cpufreq=none
>> >> >
>> >> > But you have already forced the dom0_mem to 512M. I suspect this is
>> >> > colluding with the above ballooning to make it look as if dom0 should be
>> >> > ballooned to <128M, which causes xl to print a warning message. Perhaps
>> >> > someone who understands this stuff can comment on whether or not this
>> >> > should be the case.
>> >> >
>> >> > Can you try setting "autoballoon=0" in /etc/xl.cfg.
>> >>
>> >> You mean /etc/xen/xl.conf?  I have done so and guess what?  IT WORKS!!! :)
>> >
>> > Great.
>>
>> That means default value changed if it is unset for autoballoon?
>> Original one is commented with #autoballoon = 1 in /etc/xen/xl.conf so
>> it is unset I guess so the default value for autoballoon for c/s 23110
>> is autoballoon=0 where c/s 23190 is autoballoon=1?  Just some
>> guessing... ...
>
> Can you give the full changeset numbers of what you see as 23110 and
> 23190 please, the short numbers are not globally stable and in my
> version that file is identical in both.

Both changeset of that file is the same I believe:

cat xen-4.1-testing.hg/tools/examples/xl.conf
## Global XL config file ##

# automatically balloon down dom0 when xen doesn't have enough free
# memory to create a domain
#autoballoon=1

# full path of the lockfile used by xl during domain creation
#lockfile="/var/lock/xl"

# default vif script
#vifscript="vif-bridge"

My previous comment about it is since autoballoon is not set for both
changeset in xl.conf but xl create hvm domain behaves differently
hence guessing of the difference might be related to the default value
of autoballoon (if not set in xl.conf file since it is commented).

> Ian.

Thanks.

Kindest regards,
Giam Teck Choon

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