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    Memory in vm half as fast after migration of vm.

    Scheduled Pinned Locked Moved Compute
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    • olivierlambertO Online
      olivierlambert Vates 🪐 Co-Founder CEO @Andreas
      last edited by

      @andreas That's the correct way to do it, indeed.

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      • A Offline
        Andreas @olivierlambert
        last edited by

        @olivierlambert Yes, but the problem remains
        how can you troubleshoot this or is it in xcp-ng?

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        • olivierlambertO Online
          olivierlambert Vates 🪐 Co-Founder CEO
          last edited by

          You should probably start to compare XAPI record for the VM, before and after the migration, in case anything changed.

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          • A Offline
            Andreas @olivierlambert
            last edited by

            @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.

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            • olivierlambertO Online
              olivierlambert Vates 🪐 Co-Founder CEO
              last edited by

              xe vm-param-list uuid=<VM UUID>. Compare the output before and after migration.

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              • A Offline
                Andreas @olivierlambert
                last edited by

                @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

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                • olivierlambertO Online
                  olivierlambert Vates 🪐 Co-Founder CEO
                  last edited by olivierlambert

                  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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                  • A Offline
                    Andreas @olivierlambert
                    last edited by Andreas

                    @olivierlambert
                    no this change from this
                    memory-actual ( RO): 6442455040
                    to this
                    memory-actual ( RO): 6442450944

                    and its below but they probably have no significance
                    start-time
                    console-uuids
                    dom-id
                    VCPUs-utilisation
                    guest-metrics-last-updated
                    b2471d1e-2d28-44c6-af0e-c555e9ecf100-image.png

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                    • olivierlambertO Online
                      olivierlambert Vates 🪐 Co-Founder CEO
                      last edited by

                      That's weird. We'll see if we can reproduce this. @Darkbeldin will try when he can (probably in January)

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                      • A Offline
                        Andreas @olivierlambert
                        last edited by

                        @olivierlambert
                        Okay thanks
                        and happy New Year 🙂

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                        • olivierlambertO Online
                          olivierlambert Vates 🪐 Co-Founder CEO
                          last edited by

                          You too!

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                          • A Offline
                            Andreas @olivierlambert
                            last edited by

                            @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.

                            1.Before migration.txt
                            2.After migration.txt

                            DarkbeldinD 1 Reply Last reply Reply Quote 0
                            • DarkbeldinD Offline
                              Darkbeldin Vates 🪐 Pro Support Team @Andreas
                              last edited by

                              @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.

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                              • A Offline
                                Andreas @Darkbeldin
                                last edited by

                                @darkbeldin
                                Okay Thanks

                                DarkbeldinD 1 Reply Last reply Reply Quote 0
                                • ForzaF Offline
                                  Forza @Darkbeldin
                                  last edited by

                                  @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.

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                                  • DarkbeldinD Offline
                                    Darkbeldin Vates 🪐 Pro Support Team @Andreas
                                    last edited by Darkbeldin

                                    @andreas

                                    So I was doing some testing before reporting to dev team and I have a behavior I will like you to check if you reproduce:
                                    my clean VM report like this

                                    yachy@ubuntuyachy:~$ redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q
                                    SET: 156152.41 requests per second
                                    GET: 168180.28 requests per second
                                    LPUSH: 156421.08 requests per second
                                    LPOP: 159757.17 requests per second
                                    

                                    That's my reference, when I migrate to another host it report like this:

                                    yachy@ubuntuyachy:~$ redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q
                                    SET: 55718.07 requests per second
                                    GET: 58683.72 requests per second
                                    LPUSH: 55742.91 requests per second
                                    LPOP: 54775.01 requests per second
                                    

                                    If I reboot it goes back to original reporting but if I migrate back to the original host without rebooting it report like that.

                                    redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q
                                    SET: 138092.94 requests per second
                                    GET: 153151.08 requests per second
                                    LPUSH: 147004.78 requests per second
                                    LPOP: 148115.23 requests per second
                                    

                                    So not perfect as reference but way better than after migration.
                                    As I want to be thorough before reporting could you check if you reproduce that?
                                    So:

                                    • migrate to another host
                                    • make the test
                                    • migrate back to the original host
                                    • make the test

                                    Thanks for your help.

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                                    • A Offline
                                      Andreas @Darkbeldin
                                      last edited by

                                      @darkbeldin
                                      Hello
                                      I installed clean new xcp-ng 8.2 on 2 identical PCs name host1 and host2 then updated to latest "yum update"
                                      then install a virtual machine ubuntu 20.04 with static 4GB of memory and with guest tools.
                                      Install redis-server
                                      Then I did the test
                                      on host1
                                      root@ramtest:/home/andreas# redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q
                                      SET: 243368.20 requests per second
                                      GET: 261917.23 requests per second
                                      LPUSH: 257499.67 requests per second
                                      LPOP: 264830.50 requests per second

                                      Then migrate to host2 got lower speed
                                      root@ramtest:/home/andreas# redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q
                                      SET: 92055.60 requests per second
                                      GET: 95297.09 requests per second
                                      LPUSH: 95570.31 requests per second
                                      LPOP: 95401.64 requests per second

                                      Then back to host1 got almost the same speed
                                      root@ramtest:/home/andreas# redis-benchmark -r 1000000 -n 2000000 -t get,set,lpush,lpop -P 16 -q
                                      SET: 238010.23 requests per second
                                      GET: 253100.48 requests per second
                                      LPUSH: 259100.92 requests per second
                                      LPOP: 259134.50 requests per second

                                      DarkbeldinD 1 Reply Last reply Reply Quote 0
                                      • DarkbeldinD Offline
                                        Darkbeldin Vates 🪐 Pro Support Team @Andreas
                                        last edited by

                                        @andreas Ok so migrating back to the original host give us a small perf issue but clearly not what we see when we migrate to another host.
                                        I will report it like that thanks for the test Andreas 😉

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                                        • A Offline
                                          Andreas @Darkbeldin
                                          last edited by

                                          @darkbeldin
                                          Okay
                                          Did more tests
                                          Started on host1 normal speed
                                          migrate to host2
                                          make the test got lower speed
                                          restart vm
                                          make the test on host2
                                          Got normal speed
                                          migrate to host1
                                          make the test got lower speed
                                          migrate to host2 normal speed

                                          so it seems to be something that happens after first migrating to another host

                                          I have a third exactly the same pc i should test install on it
                                          and see what happens if i move vm to host3 after moving to host2
                                          but I have to do it tomorrow, I do not have time now.

                                          DarkbeldinD 2 Replies Last reply Reply Quote 0
                                          • DarkbeldinD Offline
                                            Darkbeldin Vates 🪐 Pro Support Team @Andreas
                                            last edited by

                                            @andreas Yes i tested it no need to do it, migrating to a third hosts result to half perf has first migration.

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