On Sun, Oct 23, 2011 at 08:54:13PM +0300, Peter Peltonen wrote:
Replying to myself:
On Sun, Oct 23, 2011 at 5:51 PM, Peter Peltonen peter.peltonen@gmail.com wrote:
There is something fishy going around... I will now try to yum update dom0 and domUs, set the dom0-min-mem to 2048M and reboot and see what happens.
After rebooting I seemed to have 2048M in dom0 regardless of how many domUs were running.
But when trying to create the last domU, I was informed that xend was out of memory. At this time I still had something about 5G of real memory available for the last domU which I have configured to consume 4G of memory.
I tweaked grub.conf and xend-config.sxp and set 4096M as the dom0 memory and rebooted again. I reduced the domU memory sizes accordingly and all domUs got created without errors. But the strange thing is again dom0 memory which has been reduced from 4096M to 2052M:
[root@si ~]# cat /etc/xen/xend-config.sxp |grep dom0-min-mem # dom0-min-mem is the lowest permissible memory level (in MB) for dom0. (dom0-min-mem 4096)
[root@si ~]# xl info |grep mem total_memory : 24567 free_memory : 5853 xen_commandline : dom0_mem=4096M dom0_max_vcpus=1 dom0_vcpus_pin
[root@si ~]# xl list Name ID Mem VCPUs State Time(s) Domain-0 0 2052 1 r----- 265.6
xl top reports "(MEM)k" as "2101272" and "MAXMEM(k)" as "no limit".
In CentOS5 with Xen3 I have been used to having the amount of memory in dom0 which I have specified. My Xen4 installation seems not to do this.
If someone else is using the Xen4 packages from http://xenbits.xen.org/people/mayoung/EL6.xen I would be interested in hearing about your experiences?
Replying to an old thread.. two things:
1) you might need to use "dom0_mem=2048M,max:2048M" parameter for Xen hypervisor to give the maximum upper limit for dom0.
2) (Earlier) there was a bug in the dom0 kernel code where it allocated wrong amount of memory; you had to use "mem=2048M" option for Linux dom0 kernel in addition to the dom0_mem= option for Xen to get the correct amount of memory for dom0.
-- Pasi