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    Epyc VM to VM networking slow

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    • A Offline
      Ajmind 0 @olivierlambert
      last edited by Ajmind 0

      @olivierlambert said in Epyc VM to VM networking slow:

      I wonder about the guest kernel too (Debian 11 vs 12)

      Here are my results with Debian11 vs. Debian12 on our EPYC 7313P 16-Core Processor on the same host. Fresh and fully updated VMs with 4vcpu /4GB RAM, XCP-NG guest tools 7.30.0-11 are installed.:

      All tests were made 3 times showing the best result.

      All tests with multiple connections were made three times -P2 /-P4/-P8/-P12/-P16 showing here the best result:

      DEBIAN11>DEBIAN11
      -------------------------
      **root@deb11-master:~# iperf3 -c 192.168.1.95**
      Connecting to host 192.168.1.95, port 5201
      ------------------------------------------------
      [ ID] Interval           Transfer     Bitrate         Retr
      [  5]   0.00-10.00  sec  8.84 GBytes  7.60 Gbits/sec  1687             sender
      [  5]   0.00-10.04  sec  8.84 GBytes  7.56 Gbits/sec                  receiver
      
      **root@deb11-master:~# iperf3 -c 192.168.1.95 -P2**
      Connecting to host 192.168.1.95, port 5201
      ------------------------------------------------------------
      [SUM]   0.00-10.00  sec  12.0 GBytes  10.3 Gbits/sec  2484             sender
      [SUM]   0.00-10.04  sec  12.0 GBytes  10.3 Gbits/sec                  receiver
      
      
      DEBIAN12>DEBIAN12
      -------------------------
      **root@deb12master:~# iperf3 -c 192.168.1.98**
      Connecting to host 192.168.1.98, port 5201
      -----------------------------------------------
      [ ID] Interval           Transfer     Bitrate         Retr
      [  5]   0.00-10.00  sec  5.12 GBytes  4.40 Gbits/sec  953             sender
      [  5]   0.00-10.00  sec  5.12 GBytes  4.39 Gbits/sec                  receiver
      
      **root@deb12master:~# iperf3 -c 192.168.1.98 -P4**
      Connecting to host 192.168.1.98, port 5201
      -----------------------------------------------
      [SUM]   0.00-10.00  sec  3.58 GBytes  3.08 Gbits/sec  3365             sender
      [SUM]   0.00-10.00  sec  3.57 GBytes  3.07 Gbits/sec                  receiver
      

      Conclusion: Debian12 with kernel 6.1.55-1 compared to Debain 11 with kernel 5.10.197-1 run less performant on this EPYC host.

      I will check now if I could perform the same test with a Windows VM.

      Update

      A quick test with two Windows 7 VMs, both with 2 vcpu / 2GB RAM have shown the best result with, the latest available Citrix guest tools are installed:

      C:\Tools\Iperf3\iperf3.exe -c 192.168.1.108 -P8

      In average 11.3 GBits/sec were reached.

      1 Reply Last reply Reply Quote 0
      • olivierlambertO Offline
        olivierlambert Vates 🪐 Co-Founder CEO
        last edited by

        So we might have something weird in Debian 12 make it a lot slower 🤔

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

          Perhaps try the Debian 12 guest with mitigations=off

          1 Reply Last reply Reply Quote 0
          • bleaderB Offline
            bleader Vates 🪐 XCP-ng Team
            last edited by bleader

            Hello guys,

            I'll be the one investigating this further, we're trying to compile a list of CPUs and their behavior. First, thank you for your reports and tests, that's already very helpful and gave us some insight already.

            Setup

            If some of you can help us cover more ground that would be awesome, so here is what would be an ideal for testing to get everyone on the same page:

            • An AMD host, obviously 🙂
              • yum install iperf ²
            • 2 VMs on the same host, with the distribution of your choice¹
              • each with 4 cores if possible
              • 1GB of ram should be enough if you don't have a desktop environment to load
              • iperf2²

            ¹: it seems some recent kernels do provide a slight boost, but in any case the performance is pretty low for such high grade CPUs.
            ²: iperf3 is singlethreaded, the -P option will establish multiple connexions, but it will process all of them in a single thread, so if reaching a 100% cpu usage, it won't get much increase and won't help identifying the scaling on such a cpu. For example on a Ryzen 5 7600 processor, we do have about the same low perfomances, but using multiple thread will scale, which does not seem to be the case for EPYC Zen1 CPUs.

            Tests

            • do not disable mitigations for now, as its only on kernel side, there are still mitigation active in xen, and from my testing it doesn't seem to help much, and will increase combinatory of results
            • for each test, run xentop on host, and try to get an idea of the top values of each domain when the test is running
            • run iperf -s on VM1, and let it run (no -P X this would stop after X connexion established)
            • tests:
              • vm2vm 1 thread: on VM2, run iperf -c <ip_VM1> -t 60, note result for v2v 1 thread
              • vm2vm 4 threads on VM2, run iperf -c <ip_VM1> -t 60 -P4, note result for v2v 4 threads
              • host2vm 1 thread: on host, run iperf -c <ip_VM1> -t 60, note result for h2v 1 thread
              • host2vm 4 threads on host, run iperf -c <ip_VM1> -t 60 -P4, note result for h2v 4 threads

            Report template

            Here is an example of report template

            • Host:
              • cpu:
              • number of sockets:
              • cpu pinning: yes (detail) / no (use automated setting)
              • xcp-ng version:
              • output of xl info -n especially the cpu_topology section in a code block.
            • VMs:
              • distrib & version
              • kernel version
            • Results:
              • v2m 1 thread: throughput / cpu usage from xentop³
              • v2m 4 threads: throughput / cpu usage from xentop³
              • h2m 1 thread: througput / cpu usage from xentop³
              • h2m 4 threads: througput / cpu usage from xentop³

            ³: I note the max I see while test is running in vm-client/vm-server/host order.

            What was tested

            Mostly for information, here are a few tests I ran which did not seem to improve performances.

            • disabling the mitigations of various security issues at host and VM boot time using kernel boot parameters: noibrs noibpb nopti nospectre_v2 spectre_v2_user=off spectre_v2=off nospectre_v1 l1tf=off nospec_store_bypass_disable no_stf_barrier mds=off mitigations=off. Note this won't disable them at xen level as there are patches that enable the fixes for the related hardware with no flags to disable them.
            • disabling AVX passing noxsave in kernel boot parameters as there is a known issue on Zen CPU avoided boosting when a core is under heavy AVX load, still no changes.
            • Pinning: I tried to use a single "node" in case the memory controllers are separated, I tried avoiding the "threads" on the same core, and I tried to spread load accross nodes, althrough it seems to give a sllight boost, it still is far from what we should be expecting from such CPUs.
            • XCP-ng 8.2 and 8.3-beta1, seems like 8.3 is a tiny bit faster, but tends to jitter a bit more, so I would not deem that as relevant either.

            Not tested it myself but @nicols tried on the same machine giving him about 3Gbps as we all see, on VMWare, and it went to ~25Gbps single threaded and about 40Gbps with 4 threads, and with proxmox about 21.7Gbps (I assume single threaded) which are both a lot more along what I would expect this hardware to produce.

            @JamesG did test windows and debian guests and got about the same results.

            Althrough we do get a small boost by increasing threads (or connexions in case of iperf3), it still is far from what we can see on other setups with vmware or proxmox).

            Althrough Olivier's pool with zen4 desktop cpu do scale a lot better than EPYCs when increasing the number of threads, it still is not providing us with expected results for such powerful cpus in single thread (we do not even reach vmware single thread performances with 4 threads).

            Althrough @Ajmind-0 test show a difference between debian versions, results even on debian 11 are stil not on par with expected results.

            Disabling AVX only provided an improvement on my home FX cpu, which are known to not have real "threads" and share computing unit between 2 threads of a core, so it does make sense. (this is not shown in the table)

            It seems that memcpy in the glibc is not related to the issue, dd if=/dev/zero of=/dev/null has decent performances on these machines (1.2-1.3GBytes/s), and it's worth keeping in mind that both kernel and xen have their own implementation, so it could play a small role in filling the ring buffer in iperf, but I feel like the libc memcpy() is not at play here.

            Tests table

            I'll update this table with updated results, or maybe repost it in further post.

            Throughputs are in Gbit/s, noted as G for shorter table entries.

            CPU usages are for (VMclient/VMserver/dom0) in percentage as shown in xentop.

            user cpu family market v2v 1T v2v 4T h2v 1T h2v 4T notes
            vates fx8320-e piledriver desktop 5.64 G (120/150/220) 7.5 G (180/230/330) 9.5 G (0/110/160) 13.6 G (0/300/350) not a zen cpu, no boost
            vates EPYC 7451 Zen1 server 4.6 G (110/180/250) 6.08 G (180/220/300) 7.73 G (0/150/230) 11.2 G (0/320/350) no boost
            vates Ryzen 5 7600 Zen4 desktop 9.74 G (70/80/100) 19.7 G (190/260/300) 19.2G (0/110/140) 33.9 G (0/310/350) Olivier's pool, no boost
            nicols EPYC 7443 Zen3 server 3.38 G (?) iperf3
            nicols EPYC 7443 Zen3 server 2.78 G (?) 4.44 G (?) iperf2
            nicols EPYC 7502 Zen2 server similar ^ similar ^ iperf2
            JamesG EPYC 7302p Zen2 server 6.58 G (?) iperf3
            Ajmind-0 EPYC 7313P Zen3 server 7.6 G (?) 10.3 G (?) iperf3, debian11
            Ajmind-0 EPYC 7313P Zen3 server 4.4 G (?) 3.07G (?) iperf3, debian12
            vates EPYC 9124 Zen4 server 1.16 G (16/17/??⁴) 1.35 G (20/25/??⁴) N/A N/A !xcp-ng, Xen 4.18-rc + suse 15
            vates EPYC 9124 Zen4 server 5.70 G (100/140/200) 10.4 G (230/250/420) 10.7 G (0/120/200) 15.8 G (0/320/380) no boost
            vates Ryzen 9 5950x Zen3 desktop 7.25 G (30/35/60) 16.5 G (160/210/300) 17.5 G (0/110/140) 27.6 G (0/270/330) no boost

            ⁴: xentop on this host shows 3200% on dom0 all the time, profiling does not seem to show anything actually using CPU, but may be related to the extremely poor performance

            last updated: 2023-11-29 16:46

            All help is welcome! For those of you who already provided tests I integrated in the table, feel free to not rerun tests, it looks like following the exact protocol and provided more data won't make much of a difference and I don't want to waste your time!

            Thanks again to all of you for your insight and your patience, it looks like this is going to be a deep rabbit hole, I'll do my best to get to the bottom of this as soon as possible.

            gskgerG 1 Reply Last reply Reply Quote 3
            • S Offline
              Seneram
              last edited by

              Heya!

              Just chiming in that we (WDMAB) Are keeping tabs on this thread as well as our ongoing support ticket with you guys.

              Saw our result up on the list.
              If we can do ANYTHING further to assist then please do tell us. We are available 24/7 to solve this issue since it is very heavily impacting to our new production deployment.

              Regards.
              Mathias W.

              1 Reply Last reply Reply Quote 1
              • T Offline
                timewasted
                last edited by

                @bleader I've been investigating this issue on my own system and came across this discussion. I know this is a somewhat old thread so I hope it's ok to contribute more data here!

                Host:

                • CPU: EPYC 7302p
                • Number of sockets: 1
                • CPU pinning: no
                • XCP-NG version: 8.3 beta 2, Xen 4.17 (everything current as of the time of writing)
                • Output of xl info -n:
                host                   : xcp-ng
                release                : 4.19.0+1
                version                : #1 SMP Wed Jan 24 17:19:11 CET 2024
                machine                : x86_64
                nr_cpus                : 32
                max_cpu_id             : 31
                nr_nodes               : 1
                cores_per_socket       : 16
                threads_per_core       : 2
                cpu_mhz                : 3000.001
                hw_caps                : 178bf3ff:7ed8320b:2e500800:244037ff:0000000f:219c91a9:00400004:00000780
                virt_caps              : pv hvm hvm_directio pv_directio hap gnttab-v1 gnttab-v2
                total_memory           : 130931
                free_memory            : 24740
                sharing_freed_memory   : 0
                sharing_used_memory    : 0
                outstanding_claims     : 0
                free_cpus              : 0
                cpu_topology           :
                cpu:    core    socket     node
                  0:       0        0        0
                  1:       0        0        0
                  2:       1        0        0
                  3:       1        0        0
                  4:       4        0        0
                  5:       4        0        0
                  6:       5        0        0
                  7:       5        0        0
                  8:       8        0        0
                  9:       8        0        0
                 10:       9        0        0
                 11:       9        0        0
                 12:      12        0        0
                 13:      12        0        0
                 14:      13        0        0
                 15:      13        0        0
                 16:      16        0        0
                 17:      16        0        0
                 18:      17        0        0
                 19:      17        0        0
                 20:      20        0        0
                 21:      20        0        0
                 22:      21        0        0
                 23:      21        0        0
                 24:      24        0        0
                 25:      24        0        0
                 26:      25        0        0
                 27:      25        0        0
                 28:      28        0        0
                 29:      28        0        0
                 30:      29        0        0
                 31:      29        0        0
                device topology        :
                device           node
                No device topology data available
                numa_info              :
                node:    memsize    memfree    distances
                   0:    132338      24740      10
                xen_major              : 4
                xen_minor              : 17
                xen_extra              : .3-3
                xen_version            : 4.17.3-3
                xen_caps               : xen-3.0-x86_64 hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64
                xen_scheduler          : credit
                xen_pagesize           : 4096
                platform_params        : virt_start=0xffff800000000000
                xen_changeset          : $Format:%H$, pq ???
                xen_commandline        : dom0_mem=7568M,max:7568M watchdog ucode=scan dom0_max_vcpus=1-16 crashkernel=256M,below=4G console=vga vga=mode-0x0311
                cc_compiler            : gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1)
                cc_compile_by          : mockbuild
                cc_compile_domain      : [unknown]
                cc_compile_date        : Wed Feb 28 10:12:19 CET 2024
                build_id               : 9a011a28e29a21a7643376b36aec959253587d42
                xend_config_format     : 4
                

                Test set 1:

                Server and client were both Debian 12 (Linux 6.1.0-18-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.76-1 (2024-02-01) x86_64) with 4 cores.

                VM to VM (1 thread):

                iperf -c 192.168.1.66 -t 60
                ------------------------------------------------------------
                Client connecting to 192.168.1.66, TCP port 5001
                TCP window size: 16.0 KByte (default)
                ------------------------------------------------------------
                [  1] local 192.168.1.69 port 55530 connected with 192.168.1.66 port 5001 (icwnd/mss/irtt=14/1448/551)
                [ ID] Interval       Transfer     Bandwidth
                [  1] 0.0000-60.0213 sec  38.2 GBytes  5.47 Gbits/sec
                
                xentop: 100 / 150 / 250
                

                VM to VM (4 threads):

                iperf -c 192.168.1.66 -t 60 -P4
                ------------------------------------------------------------
                Client connecting to 192.168.1.66, TCP port 5001
                TCP window size: 16.0 KByte (default)
                ------------------------------------------------------------
                [  2] local 192.168.1.69 port 35702 connected with 192.168.1.66 port 5001 (icwnd/mss/irtt=14/1448/531)
                [  4] local 192.168.1.69 port 35708 connected with 192.168.1.66 port 5001 (icwnd/mss/irtt=14/1448/576)
                [  1] local 192.168.1.69 port 35714 connected with 192.168.1.66 port 5001 (icwnd/mss/irtt=14/1448/458)
                [  3] local 192.168.1.69 port 35692 connected with 192.168.1.66 port 5001 (icwnd/mss/irtt=14/1448/744)
                [ ID] Interval       Transfer     Bandwidth
                [  2] 0.0000-60.0141 sec  12.4 GBytes  1.77 Gbits/sec
                [  1] 0.0000-60.0129 sec  13.9 GBytes  1.99 Gbits/sec
                [  3] 0.0000-60.0141 sec  14.5 GBytes  2.07 Gbits/sec
                [  4] 0.0000-60.0301 sec  12.2 GBytes  1.75 Gbits/sec
                [SUM] 0.0000-60.0071 sec  53.0 GBytes  7.58 Gbits/sec
                
                xentop: 165 / 200 / 380
                

                Host to VM (1 thread):

                iperf -c 192.168.1.66 -t 60
                ------------------------------------------------------------
                Client connecting to 192.168.1.66, TCP port 5001
                TCP window size:  297 KByte (default)
                ------------------------------------------------------------
                [  3] local 192.168.1.1 port 37804 connected with 192.168.1.66 port 5001
                [ ID] Interval       Transfer     Bandwidth
                [  3]  0.0-60.0 sec  6.58 GBytes   942 Mbits/sec
                
                xentop: N/A / 135 / 145
                

                Host to VM (4 threads):

                iperf -c 192.168.1.66 -t 60 -P4
                ------------------------------------------------------------
                Client connecting to 192.168.1.66, TCP port 5001
                TCP window size:  112 KByte (default)
                ------------------------------------------------------------
                [  5] local 192.168.1.1 port 37812 connected with 192.168.1.66 port 5001
                [  3] local 192.168.1.1 port 37808 connected with 192.168.1.66 port 5001
                [  6] local 192.168.1.1 port 37814 connected with 192.168.1.66 port 5001
                [  4] local 192.168.1.1 port 37810 connected with 192.168.1.66 port 5001
                [ ID] Interval       Transfer     Bandwidth
                [  3]  0.0-60.0 sec  1.63 GBytes   233 Mbits/sec
                [  6]  0.0-60.0 sec  2.08 GBytes   298 Mbits/sec
                [  4]  0.0-60.0 sec  1.07 GBytes   154 Mbits/sec
                [  5]  0.0-60.0 sec  1.80 GBytes   257 Mbits/sec
                [SUM]  0.0-60.0 sec  6.58 GBytes   942 Mbits/sec
                
                xentop: N/A / 155 / 155
                

                Test set 2:

                Server: FreeBSD 14 (FreeBSD 14.0-RELEASE (GENERIC) #0 releng/14.0-n265380-f9716eee8ab4: Fri Nov 10 05:57:23 UTC 2023) with 4 cores.
                Client: Debian 12 (Linux 6.1.0-18-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.76-1 (2024-02-01) x86_64) with 4 cores.

                VM to VM (1 thread):

                iperf -c 192.168.1.64 -t 60
                ------------------------------------------------------------
                Client connecting to 192.168.1.64, TCP port 5001
                TCP window size: 16.0 KByte (default)
                ------------------------------------------------------------
                [  1] local 192.168.1.69 port 38572 connected with 192.168.1.64 port 5001 (icwnd/mss/irtt=14/1448/905)
                [ ID] Interval       Transfer     Bandwidth
                [  1] 0.0000-60.0089 sec  21.3 GBytes  3.04 Gbits/sec
                
                xentop: 125 / 355 / 325
                

                VM to VM (4 threads):

                iperf -c 192.168.1.64 -t 60 -P4
                ------------------------------------------------------------
                Client connecting to 192.168.1.64, TCP port 5001
                TCP window size: 16.0 KByte (default)
                ------------------------------------------------------------
                [  3] local 192.168.1.69 port 50068 connected with 192.168.1.64 port 5001 (icwnd/mss/irtt=14/1448/753)
                [  1] local 192.168.1.69 port 50078 connected with 192.168.1.64 port 5001 (icwnd/mss/irtt=14/1448/513)
                [  4] local 192.168.1.69 port 50088 connected with 192.168.1.64 port 5001 (icwnd/mss/irtt=14/1448/411)
                [  2] local 192.168.1.69 port 50070 connected with 192.168.1.64 port 5001 (icwnd/mss/irtt=14/1448/676)
                [ ID] Interval       Transfer     Bandwidth
                [  4] 0.0000-60.0299 sec  9.48 GBytes  1.36 Gbits/sec
                [  1] 0.0000-60.0299 sec  6.56 GBytes   938 Mbits/sec
                [  3] 0.0000-60.0301 sec  11.2 GBytes  1.60 Gbits/sec
                [  2] 0.0000-60.0293 sec  6.61 GBytes   947 Mbits/sec
                [SUM] 0.0000-60.0146 sec  33.8 GBytes  4.84 Gbits/sec
                
                xentop: 220 / 400 / 730
                

                Host to VM (1 thread):

                iperf -c 192.168.1.64 -t 60
                ------------------------------------------------------------
                Client connecting to 192.168.1.64, TCP port 5001
                TCP window size:  212 KByte (default)
                ------------------------------------------------------------
                [  3] local 192.168.1.1 port 58464 connected with 192.168.1.64 port 5001
                [ ID] Interval       Transfer     Bandwidth
                [  3]  0.0-60.0 sec  6.58 GBytes   941 Mbits/sec
                
                xentop: N/A / 295 / 205
                

                Host to VM (4 threads):

                iperf -c 192.168.1.64 -t 60 -P4
                ------------------------------------------------------------
                Client connecting to 192.168.1.64, TCP port 5001
                TCP window size:  130 KByte (default)
                ------------------------------------------------------------
                [  5] local 192.168.1.1 port 58470 connected with 192.168.1.64 port 5001
                [  3] local 192.168.1.1 port 58468 connected with 192.168.1.64 port 5001
                [  4] local 192.168.1.1 port 58472 connected with 192.168.1.64 port 5001
                [  6] local 192.168.1.1 port 58474 connected with 192.168.1.64 port 5001
                [ ID] Interval       Transfer     Bandwidth
                [  5]  0.0-60.0 sec  1.73 GBytes   247 Mbits/sec
                [  3]  0.0-60.0 sec  1.56 GBytes   224 Mbits/sec
                [  4]  0.0-60.0 sec  1.73 GBytes   247 Mbits/sec
                [  6]  0.0-60.0 sec  1.56 GBytes   224 Mbits/sec
                [SUM]  0.0-60.0 sec  6.58 GBytes   942 Mbits/sec
                
                xentop: N/A / 280 / 205
                

                Conclusion:

                No special tuning on any of the VMs, just a fresh install from the netboot ISO for each respective OS.

                I also don't fully understand why my host seems to be limited to 1Gb. The management interface is 1Gb, but that shouldn't matter? The other physical NIC is 10Gb SFP+, just for the sake of completeness.

                Please let me know if there's anything at all that I can do to help with this!

                bleaderB 1 Reply Last reply Reply Quote 1
                • olivierlambertO Offline
                  olivierlambert Vates 🪐 Co-Founder CEO
                  last edited by

                  FYI, we are discussing with AMD and another external company to find the culprit, active work is in the pipes.

                  1 Reply Last reply Reply Quote 3
                  • bleaderB Offline
                    bleader Vates 🪐 XCP-ng Team @timewasted
                    last edited by

                    @timewasted Thanks for sharing, as long as we haven't found a solution, it is always good to have more feedback, so thanks for that.

                    For FreeBSD it usus the same principle of network driver, but it seems to have lower performances, not only on EPYC system, this could be another investigation for later 🙂

                    I am indeed surprised by your vm/host results, I generally get a way greater performance there in my tests. I agree the management NIC speed should not impact it at all… You said no tuning so I guess no pinning or anything, therefore I don't really see why that is right now.

                    M 1 Reply Last reply Reply Quote 0
                    • M Offline
                      manilx @bleader
                      last edited by

                      @bleader I stumpled upon this thread and this issue kept me wondering so I did a quick test on our systems:

                      Running iperf3 on ou HP's with AMD EPYC 7543P cpu's, debian12 to debian12 vm I get
                      iperf3 -c 192.168.1.19 -P 10
                      ScreenShot 2024-04-02 at 10.10.40.png

                      iperf3 -c 192.168.1.19
                      ScreenShot 2024-04-02 at 10.11.40.png

                      Same on a HP with Intel Xeon E5-2667
                      iperf3 -c 192.168.1.113 -P 10
                      ScreenShot 2024-04-02 at 10.16.52.png

                      iperf3 -c 192.168.1.113
                      ScreenShot 2024-04-02 at 10.17.42.png

                      FREAKY!

                      Doesn't affect us because we don't have inter-VM traffic to speak off.

                      bleaderB 1 Reply Last reply Reply Quote 1
                      • bleaderB Offline
                        bleader Vates 🪐 XCP-ng Team @manilx
                        last edited by bleader

                        @manilx thanks for the additional results, and yes, it is a pretty big issue, but even with multiple people looking at it or trying to help out, we were not able to pinpoint the root cause yet 😞

                        N 1 Reply Last reply Reply Quote 0
                        • N Offline
                          nicols @bleader
                          last edited by

                          This is over 4 months old, and is affecting a LOT of my customers.
                          It is a BIG problem for my company.

                          Is there anything that we can do to help resolve this?

                          S 1 Reply Last reply Reply Quote 0
                          • S Offline
                            Seneram @nicols
                            last edited by

                            @nicols Hello, you are not alone in this. We have delayed the deployment of our core ISP routing as virtual routers due to this.

                            We have an XOA premium and xcp-ng enterprise subscription and an open case on this.

                            I cannot go into detail about what is being said in there but i can say that the approach @olivierlambert and vates have is very good and they have my full confidence on this one.

                            @manilx i can say this affects all vm traffic as we have vm out to switch over to a second hardware host into a VM there and we see the limit there aswell just the roof is twice as high as inside the same HW box

                            Either way. Vates is VERY well aware of how serious this is and are taking good efforts to fix it.

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                            • M Offline
                              manilx @Seneram
                              last edited by

                              @Seneram True. Just tested 2 debian12 sitting on 2 EPYC host:

                              10 parallel tests:

                              ScreenShot 2024-04-02 at 10.57.11.png

                              One:
                              ScreenShot 2024-04-02 at 10.58.12.png

                              Bummer! Worse than I thought. But Vates will certainly get to the bottom of this.

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

                                Just for additional insights, have tests been made with different BIOS/firmware settings? Especially EPYC firmware has a lot of settings affecting internal latency vs throughput for different workloads. I recently deployed an EPYC 2x48c/96t system for a simulation software. The changes in the firmware could make 20% difference in rendering time for this application. Not saying it is a root cause, but it could possibly improve the situation here. My guess is that much of the issue is due to bad latency and erroneous scheduling leading to additional latency.

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                                • S Offline
                                  Seneram @Forza
                                  last edited by

                                  @Forza We have tried all the settings avail to tweak on our hardware, We have a full big twin chassi we have dedicated to vates doing testing of this issue and the first roughly month was spent going over settings together with vates and making sure everything was tweaked properly.

                                  AMD is involved themself and if anyone knows AMD firmware settings and tweaking it would be AMD.

                                  In all seriousness it is a very good suggestion but it has been looked into and unfortunately do minimal or no difference.

                                  ForzaF 1 Reply Last reply Reply Quote 1
                                  • ForzaF Offline
                                    Forza @Seneram
                                    last edited by

                                    @Seneram thanks, was guessing it was the case. I hope the issue is resolved soon. 🙏

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

                                      Please note that we are actively investigating to it, and believe me it's costly (25k€ already invested to track this down). So as you can see, it's a priority and something we are actively working on. AMD is also aware of it.

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                                      • gskgerG Offline
                                        gskger Top contributor @bleader
                                        last edited by gskger

                                        @bleader Had some time to test this on an AMD system (HP T740 Thin Client). Hopefully it helps a bit, even it is not an Epyc CPU.

                                        Host:

                                        • CPU: AMD Ryzen Embedded V1756B
                                        • Number of sockets: 1
                                        • CPU pinning: no
                                        • XCP-NG version: 8.3 beta 1 (updated with yum update as of today)
                                        • Output of xl info -n:
                                        [22:05 hpt740 ~]# xl info -n
                                        host                   : hpt740
                                        release                : 4.19.0+1
                                        version                : #1 SMP Wed Jan 24 17:19:11 CET 2024
                                        machine                : x86_64
                                        nr_cpus                : 8
                                        max_cpu_id             : 15
                                        nr_nodes               : 1
                                        cores_per_socket       : 4
                                        threads_per_core       : 2
                                        cpu_mhz                : 3244.038
                                        hw_caps                : 178bf3ff:7ed8320b:2e500800:244033ff:0000000f:209c01a9:00000000:00000500
                                        virt_caps              : pv hvm hvm_directio pv_directio hap shadow
                                        total_memory           : 30636
                                        free_memory            : 17610
                                        sharing_freed_memory   : 0
                                        sharing_used_memory    : 0
                                        outstanding_claims     : 0
                                        free_cpus              : 0
                                        cpu_topology           :
                                        cpu:    core    socket     node
                                          0:       0        0        0
                                          1:       0        0        0
                                          2:       1        0        0
                                          3:       1        0        0
                                          4:       2        0        0
                                          5:       2        0        0
                                          6:       3        0        0
                                          7:       3        0        0
                                        device topology        :
                                        device           node
                                        No device topology data available
                                        numa_info              :
                                        node:    memsize    memfree    distances
                                           0:     34803      17610      10
                                        xen_major              : 4
                                        xen_minor              : 13
                                        xen_extra              : .5-10.58
                                        xen_version            : 4.13.5-10.58
                                        xen_caps               : xen-3.0-x86_64 hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64
                                        xen_scheduler          : credit
                                        xen_pagesize           : 4096
                                        platform_params        : virt_start=0xffff800000000000
                                        xen_changeset          : 708e83f0e7d1, pq 8e58b4872724
                                        xen_commandline        : watchdog ucode=scan dom0_max_vcpus=1-8 crashkernel=256M,below=4G console=vga vga=mode-0x0311 dom0_mem=4294967296B,max:4294967296B
                                        cc_compiler            : gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1)
                                        cc_compile_by          : mockbuild
                                        cc_compile_domain      : [unknown]
                                        cc_compile_date        : Thu Jan 25 10:20:16 CET 2024
                                        build_id               : ae0904d024e04d4daf2ecdfddc37ea146f48d7e1
                                        xend_config_format     : 4
                                        

                                        Server and client VMs are both Debian 12 (Linux 6.1.0-18-amd64) with 4 cores and 4G RAM. xentop is client/server/dom0

                                        V2V 1T   90/140/210   5.1 Gbits/sec
                                        V2V 4T  150/220/260   8.1 Gbits/sec 
                                        H2V 1T    0/170/210  10.2 Gbits/sec*
                                        H2V 4T    0/310/340  11.9 Gbits/sec*
                                        *: with some spread of cpu utilization and throughput
                                        

                                        Minimum of three runs per test scenario.

                                        bleaderB 1 Reply Last reply Reply Quote 0
                                        • olivierlambertO Offline
                                          olivierlambert Vates 🪐 Co-Founder CEO
                                          last edited by

                                          We made tests on Ryzen CPUs and we couldn't really reproduce the problem: it seems to be EPYC specific.

                                          bleaderB 1 Reply Last reply Reply Quote 1
                                          • bleaderB Offline
                                            bleader Vates 🪐 XCP-ng Team @olivierlambert
                                            last edited by

                                            @olivierlambert We did talk in DM before, I told him any data is always welcome, especially as I didn't even know this range of CPUs 🙂

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