Michal,
I checked the virtio_mem module and it's loaded -
virtio_mem 32768 0
And I can't make the actual value change to non-zerio.
-> virsh update-memory pc --requested-size 256M
or
->virsh setmem pc 1000M
<memory model='virtio-mem'>
<target>
<size unit='KiB'>524288</size>
<node>0</node>
<block unit='KiB'>2048</block>
<requested unit='KiB'>262144</requested>
<actual unit='KiB'>0</actual>
</target>
<alias name='virtiomem0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
</memory>
<target>
<size unit='KiB'>524288</size>
<node>0</node>
<block unit='KiB'>2048</block>
<requested unit='KiB'>262144</requested>
<actual unit='KiB'>0</actual>
</target>
<alias name='virtiomem0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x0a' function='0x0'/>
</memory>
Any other suggestions ?
> This is a bummer. What this represents is the actual value of membaloon.> Yes and no. It shows that we need <actual/> because guest might ignore
> request to change the requested size. What you're probably experiencing
> is that you haven't loaded virtio_mem module and thus the virtio-mem
> device is ignoring requests for change (well, kernel is ignoring them,
> whatever).
> request to change the requested size. What you're probably experiencing
> is that you haven't loaded virtio_mem module and thus the virtio-mem
> device is ignoring requests for change (well, kernel is ignoring them,
> whatever).
On Thu, Feb 4, 2021 at 12:27 AM Michal Privoznik <mprivozn@xxxxxxxxxx> wrote:
On 2/3/21 7:11 AM, Jing Qi wrote:
> I did some test for virtio-mem with libvirt upstream version
> v7.0.0-153-g5ea3ecd07d
> & qemu-kvm-5.2.0-0.7.rc2.fc34.x86_64
>
> S1. Start domain with memory device
>
> 1. Domain configuration-
> <maxMemory slots='16' unit='KiB'>10485760</maxMemory>
> <memory unit='KiB'>1572864</memory>
> <currentMemory unit='KiB'>1572864</currentMemory>
> ...
> <cpu mode='host-model' check='partial'>
> <numa>
> <cell id='0' cpus='0-3' memory='1048576' unit='KiB'/>
> </numa>
> </cpu>
> ...
> <memory model='virtio-mem'>
> <target>
> <size unit='KiB'>524288</size>
> <node>0</node>
> <block unit='KiB'>2048</block>
> <requested unit='KiB'>393216</requested>
> </target>
> <address type='pci' domain='0x0000' bus='0x00' slot='0x0a'
> function='0x0'/>
> </memory>
> #virsh start pc
> Domain 'pc' started
>
> 2. The domain is started and check mem status, the actual size is "1048576"
> #virsh dommemstat pc
> actual 1048576
This is a bummer. What this represents is the actual value of membaloon.
> swap_in 0
> swap_out 0
> major_fault 257
> minor_fault 130540
> unused 604064
> available 761328
> usable 578428
> last_update 1612325471
> disk_caches 49632
> hugetlb_pgalloc 0
> hugetlb_pgfail 0
> rss 460260
>
> 3. Then, check the active xml -
> # virsh dumpxml pc
> ...
> <memory unit='KiB'>1572864</memory>
> <currentMemory unit='KiB'>1048576</currentMemory>
> ....
> <memory model='virtio-mem'>
> <target>
> <size unit='KiB'>524288</size>
> <node>0</node>
> <block unit='KiB'>2048</block>
> <requested unit='KiB'>393216</requested>
> <actual unit='KiB'>0</actual>
> </target>
> <alias name='virtiomem0'/>
> <address type='pci' domain='0x0000' bus='0x00' slot='0x0a'
> function='0x0'/>
> </memory>
>
> Question1 : the value of actual is "0". Is it expected?
Yes and no. It shows that we need <actual/> because guest might ignore
request to change the requested size. What you're probably experiencing
is that you haven't loaded virtio_mem module and thus the virtio-mem
device is ignoring requests for change (well, kernel is ignoring them,
whatever).
>
> S2. Also, tried to use hugepage to start the domain -
>
> <memory model='virtio-mem'>
> <target>
> <size unit='KiB'>524288</size>
> <node>0</node>
> <block unit='KiB'>2048</block>
> <requested unit='KiB'>393216</requested>
> <actual unit='KiB'>0</actual>
> </target>
> <alias name='virtiomem0'/>
> <address type='pci' domain='0x0000' bus='0x00' slot='0x0a'
> function='0x0'/>
> </memory>
>
> #virsh start pc
> error: Failed to start domain 'pc'
> error: internal error: process exited while connecting to monitor:
> 2021-02-03T05:50:33.157836Z qemu-system-x86_64: -object
> memory-backend-file,id=memvirtiomem0,mem-path=/dev/hugepages/libvirt/qemu/9-pc,size=536870912,host-nodes=0,policy=bind:
> can't open backing store /dev/hugepages/libvirt/qemu/9-pc for guest RAM:
> Permission denied
>
> Question 2: any bug here?
Ah, good catch! I'll fix this in v2.
Michal
Thanks & Regards,
Jing,Qi
Jing,Qi
