memory seen by a _service_ VM is different than set in Dom0

[marmarek]

Reported by joanna on 2 Jul 2011 10:53 UTC
free -m shows larger amount of memory than set via qvm-pref, and reported by qvm-ls.

Migrated-From: https://wiki.qubes-os.org/ticket/259

[marmarek]

Comment by rafal on 20 Jul 2011 11:34 UTC
This looks like the kernel bug. Affects not only servicevms.
This is "fixed" by qmemman doing xl memset. That is why it is not visible in normal appvms. However, if I "xl start" an appvm manually with init=/bin/bash, there is a similar difference visible as well.

I think simply the memory amount reported by /proc/meminfo is miscalculated. If I do

xl memset firewallvm 199
xl memset firewallvm 200

then there is no change in xen free memory (or vms memory), but the meminfo shows 200 correctly then.

It can be worked around by adding

MEMKB=$(grep Current /proc/xen/balloon|sed -e 's/ kB//' -e 's/.* //')
echo $((($MEMKB-1)*1024)) > /proc/xen/balloon

somewhere in a VM init.d script. Or do we want to file a ticket for suse folks and wait for a clean solution ?

[marmarek]

Comment by rafal on 20 Jul 2011 11:34 UTC
This looks like the kernel bug. Affects not only servicevms.
This is "fixed" by qmemman doing xl memset. That is why it is not visible in normal appvms. However, if I "xl start" an appvm manually with init=/bin/bash, there is a similar difference visible as well.

I think simply the memory amount reported by /proc/meminfo is miscalculated. If I do

xl memset firewallvm 199
xl memset firewallvm 200

then there is no change in xen free memory (or vms memory), but the meminfo shows 200 correctly then.

It can be worked around by adding

MEMKB=$(grep Current /proc/xen/balloon|sed -e 's/ kB//' -e 's/.* //')
echo $((($MEMKB-1)*1024)) > /proc/xen/balloon

somewhere in a VM init.d script. Or do we want to file a ticket for suse folks and wait for a clean solution ?

[marmarek]

Comment by joanna on 25 Jul 2011 08:13 UTC
File a ticket (perhaps to xen-devel as well?). Moving this to Beta 3. Reducing this to minor (and perhaps we will move it to Beta 3, while waiting for the official fix).

[marmarek]

Comment by joanna on 25 Jul 2011 08:13 UTC
File a ticket (perhaps to xen-devel as well?). Moving this to Beta 3. Reducing this to minor (and perhaps we will move it to Beta 3, while waiting for the official fix).

[marmarek]

Modified by joanna on 28 Jul 2011 09:34 UTC

[marmarek]

Modified by joanna on 28 Jul 2011 09:34 UTC

[marmarek]

Comment by joanna on 18 Jan 2012 10:12 UTC
It doesn't seem to harm anybody, and is strictly a Xen/kernel problem.

[marmarek]

Comment by joanna on 18 Jan 2012 10:12 UTC
It doesn't seem to harm anybody, and is strictly a Xen/kernel problem.