[Xen-devel] xen balloon issue?

["Robbie Garertt" <rgarrett@xxxxxxxxxxxxxx>]

I know this may not be the correct place here and hopefully I will not get flamed for this but I am searching for an answer to my problem and I think it may be a bug?

 

I have a xen server setup and running version 3.4.2. Kernel version is 2.6.31.12.

My issue here is that when I do a free -m within the Vm is shows less, some times more ram then what the config files shows.   Here is an example of what I see from xend starting the domU.

[2010-03-14 17:09:45 2598] DEBUG (balloon:166) Balloon: 7766704 KiB free; need 526336; done.

526336 /1024 = 514MB

When I do a free -m within the domU I get it showing me a total of 506mb.

when I do cat /proc/meminfo is shows a total of 518220 which is 506mb.

 

 

It would appear that for what ever reason my system is off by 19MB when it comes to 512mb, and 28mb per gb.   I had to set my testing.cfg file to 531MB to get free -m to show 512mb of total memory inside a domU and 1052 to get it to so show 1024.

 

can anyone provide any insight as to why or where i may go in an attempt to get this solved?  20mb adds up to a lot when you run several domu's

 

Config options below.

 

Made the dom0 and domU kernel by doing

git clone git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git linux-2.6-xen
cd linux-2.6-xen

make && make modules && make modules_install && make bzImage && make install

 

my domU config is

kernel      = '/boot/vmlinuz-2.6.31.12-XenDom0'
ramdisk     = '/boot/initrd.img-2.6.31.12-XenDom0'

memory      = '512'

#
#  Disk device(s).
#
root        = '/dev/xvda2 ro'
disk        = [
                  'phy:/dev/Xen/Testing-disk,xvda2,w',
                  'phy:/dev/Xen/Testing-swap,xvda1,w',
              ]

#
#  Physical volumes
#

 

#
#  Hostname
#
name        = 'Testing'

#
#  Networking
#
vif         = [ 'ip=192.168.5.2,mac=00:16:3E:78:FB:92' ]

#
#  Behaviour
#

on_reboot   = 'restart'
on_crash    = 'restart'

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