Memory in vm half as fast after migration of vm.
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Hi,
Are you using dynamic memory? If yes, please disable it and try again.
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@olivierlambert Okay I'll try it but where do I see if it has dynamic memory
i xen Orchestra?
I have previously used xcp-ng center. -
Advanced view of the VM, check if static max = dynamic min = dynamic max.
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@olivierlambert no it says
Static: 512 MiB / 32 GiB Dynamic: 1 GiB / 32 GiBshould I change to this to make it static
Static: 32 GIB / 32 GiB Dynamic: 32 GiB / 32 GiBbecause I do not see where I can delete Dynamic
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@olivierlambert
I have set it to thisStatic: 512 MiB/32 GiB Dynamic: 32 GiB/32 GiBcould not change static value
okay did a migration again
but unfortunately the same resultBefore migration
#redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q SET: 223363.84 requests per second GET: 235793.44 requests per second LPUSH: 247954.38 requests per second LPOP: 251572.33 requests per secondAfter migration
#redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q SET: 111844.31 requests per second GET: 118119.54 requests per second LPUSH: 116083.34 requests per second LPOP: 116795.14 requests per secondAfter reboot off VM on the second server
#redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q SET: 244468.91 requests per second GET: 254647.31 requests per second LPUSH: 261848.66 requests per second LPOP: 261574.69 requests per second -
@andreas That's the correct way to do it, indeed.
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@olivierlambert Yes, but the problem remains
how can you troubleshoot this or is it in xcp-ng? -
You should probably start to compare XAPI record for the VM, before and after the migration, in case anything changed.
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@olivierlambert XAPI records this is a bit beyond my knowledge.
I tried to make a brand new VM Ubuntu 20.04 server
just to see so it was not the virtual machine it was wrong in but
unfortunately the same result again. -
xe vm-param-list uuid=<VM UUID>. Compare the output before and after migration. -
@olivierlambert
Okay find a value that is different
the test is done on the new VM which has 6 GIB in Ram
This is the value before migration
memory-target ( RO): 0
after migration
memory-target ( RO): 6442450944
and after reboot of VM
memory-target ( RO): 0 -
That's weird, despite the fact your VM is set to static, right? (same dynamic min, max and static max?)
edit: is it the only diff?
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@olivierlambert
no this change from this
memory-actual ( RO): 6442455040
to this
memory-actual ( RO): 6442450944and its below but they probably have no significance
start-time
console-uuids
dom-id
VCPUs-utilisation
guest-metrics-last-updated
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That's weird. We'll see if we can reproduce this. @Darkbeldin will try when he can (probably in January)
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@olivierlambert
Okay thanks
and happy New Year
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You too!
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@olivierlambert
Sorry to disturb you.
Okay just to verify that there was nothing wrong with the physical servers.
So I took 2 identical PCs and installed clean new xcp-ng 8.2
then install a virtual machine with static 4GB of memory and with guest tools.
Install redis and ran the test
then migrated VM to other pc and ran the test and the speed was half.
Took out the result before and after attached the files. -
@andreas Hi Andreas,
After testing it on my side i can confirm i reproduce the issue.
I will discuss it at dev level and get back to you. -
@darkbeldin
Okay Thanks -
@darkbeldin said in Memory in vm half as fast after migration of vm.:
@andreas Hi Andreas,
After testing it on my side i can confirm i reproduce the issue.
I will discuss it at dev level and get back to you.This seems quite an important find. Please let is know how this goes.
