From: [email protected] [mailto:[email protected]] On
Behalf Of Adnan Mundres
Sent: Wednesday, January 24, 2018 6:54 PM
To: [email protected]
Subject: [libvirt] with vhostuser I cannot use hugepages
In my setup I am using qemu-kvm without openstack. I am trying to use ovs with
dpdk. In my xml file I added following lines for the dpdkvhostuser
<cpu mode='host-passthrough'>
<numa>
<cell id="0" cpus="0-6" memory="16777216" unit='KiB' memAccess="shared"/>
</numa>
</cpu>
[Mooney, Sean K] this xml snippit is not requsting the use of huge page memory.
It is requesting memory to be allocated form a single numa node and for that
to be mmaped shared.
Dpdk does not actually need the guest to use hugepages it just improves the
performance. What it requires
Is that the gues uses file descriptor backed, pre allocated, locked, shared
memory.
e.g.
<memoryBacking>
<locked/>
<source type='file'/>
<access mode='shared'/>
<allocation mode='immediate'/>
</memoryBacking>
Hugepages will enable all of the above features implicitly.
to enable hugepages add
<memoryBacking>
<hugepages>
<page size="16" unit="G" nodeset="0"/>
</hugepages>
</memoryBacking>
I have enabled hugepages during boot time
ot@mvmgptb11hyp01 hyp-1]# cat /proc/meminfo | grep -i huge
AnonHugePages: 126976 kB
HugePages_Total: 100
HugePages_Free: 80
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 1048576 kB
But When I start my vm (virsh start vm1.xml) I am seeing that this vm is not
using memory from hugepages, rather it is taking memory from total memory. When
I checked the log file I see that it is using
-object
memory-backend-file,id=ram-node0,prealloc=yes,mem-path=/var/lib/libvirt/qemu/ram,share=yes
It should use backend memory as following
-object
memory-backend-file,id=ram-node0,prealloc=yes,mem-path=/dev/hugepages/libvirt/qemu/vm1,share=yes
Any idea how can I use memory from hugepages
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