Hi All,
I have an obscure issue that I hope someone here can help with. We are trying to make our QEMU/KVM hypervisors more NUMA aware and are trying to stop KSM from merging memory across NUMA nodes. The problem is, on several of our host we cannot write to /sys/kernel/mm/ksm/merge_across_nodes, for instance.
echo 0 > /sys/kernel/mm/ksm/merge_across_nodes
-bash: echo: write error: Device or resource busy
Reading works fine;
cat /sys/kernel/mm/ksm/merge_across_nodes
1
Attempting to change the setting using virsh throws a similar error;
virsh node-memory-tune --shm-merge-across-nodes 0
error: Unable to change memory parameters
error: failed to set shm_merge_across_nodes: Operation not permitted
The issue only effects a subset of server, though all servers should be configured fairly identically and are running fairly recent CentOS 7.2 packages installed from an internal repo. I’m unsure what could cause this.
uname -a
Linux XXXXXXXXXXXXXXX 3.10.0-327.28.2.el7.x86_64 #1 SMP Wed Aug 3 11:11:39 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
virsh --version
1.2.17
yum info qemu-kvm | grep Version
Version : 1.5.3
Regards,
Oisin
Oisin O'Malley
Systems Engineer
Iocane Pty Ltd
763 South Road
Black Forest SA 5035
Office:+61 (8) 8413 1010
Fax:+61 (8) 8231 2050
Email:oisin.omalley@xxxxxxxxxxxxx
Web:www.iocane.com.au
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