@olivierlambert yes, but this is only a small improvement to overall problem. Still, compared to similar intel platform, v2v network performance is very low. Are there any news for the final solution to this problem?

@peter_webbird i think i have the same issue, it happens also when trying to move disk to another SR:
https://xcp-ng.org/forum/topic/9618/disk-move-fails-vm-crashes

Probably related and/or similar (but not the same) as: https://xcp-ng.org/forum/topic/9087/migrate-vm-disk-operation-blocked

After performing backup job, options "migrate_send" and "pool_migrate" disappear from "allowed-operations" parametar. In such state, VM can be migrated with Xen Orchestra and xe toolstack (CLI), but cannot be migrated from XCP-NG Centar.

Before backup job:

allowed-operations (SRO): changing_dynamic_range; migrate_send; pool_migrate; changing_VCPUs_live; suspend; hard_reboot; hard_shutdown; clean_reboot; clean_shutdown; pause; checkpoint; snapshot
blocked-operations (MRW): 

during backup:

allowed-operations (SRO): changing_dynamic_range; changing_VCPUs_live; suspend; hard_reboot; hard_shutdown; clean_reboot; clean_shutdown; pause; checkpoint; snapshot
blocked-operations (MRW): migrate_send: VM migration is blocked during backup; pool_migrate: VM migration is blocked during backup

after backup is finished:

allowed-operations (SRO): changing_dynamic_range; changing_VCPUs_live; suspend; hard_reboot; hard_shutdown; clean_reboot; clean_shutdown; pause; checkpoint; snapshot
blocked-operations (MRW): 

If we perform reset of XAPI toolstack, everything is OK (options "migrate_send" and "pool_migrate" are back on "allowed-operations"). Also, if we perform migration with Xen Orchestra or power cycle VM, everything works temporarily, until next backup job.

We have latest Xen Orchestra from sources (Xen Orchestra: commit 0e6bc, Master: commit 0e6bc).
This bug was also present on older Xen Orchestra (also from sources, installed at 19.06.2024).
XCP-ng Centar is also latest release (20.04.01.33). XCP-ng Pool is at 8.2, all updates applied.
We use Delta backups, and did a test with creating new job (with just one VM).

Best regards!

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?

@nicols said in Epyc VM to VM networking slow:

Today, i got my hands on HPE ProLiant DL325 Gen10 server with Epyc 7502 32 core (64 threads) CPU. I have installed XCP-ng 8.2.1, and applied all pathes wth yum update. Installed 2 Debian and 2 Windows 10 VMs. Results are very similar:

Linux to Linux VM on single host: 4 Gbit/sec on single thread, max 6 Gbit/sec on mulčtiple threads.
I have tried various amountss of VCPU (2,4,8.12,16) and various combinations of iperf threads.

Windws to Windows VM: 3.5 Gbit/sec on single thread, and 18 Gbit/sec um multiple threads.

All this was with default bios settings, just changed to legacy boot.
Wet performance tuning in bios (c states and other settings), i believe i can get 10-15% more, i will try that tommorow.

So, i think this confirms that this is not Supermicro related problem, but something on relation Xen (hypervisor?) <-> AMD CPU.

Same hardware, VmWare ESXi 8.0, Debian 12 VMs with 4 vCPU and 2GB RAM.

root@debian-on-vmwareto:~# iperf -c 10.33.65.159
------------------------------------------------------------
Client connecting to 10.33.65.159, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 10.33.65.160 port 59124 connected with 10.33.65.159 port 5001 (icwnd/mss/irtt=14/1448/164)
[ ID] Interval       Transfer     Bandwidth
[  1] 0.0000-10.0094 sec  29.0 GBytes  24.9 Gbits/sec

with more threads:

root@debian-on-vmwareto:~# iperf -c 10.33.65.159 -P4
------------------------------------------------------------
Client connecting to 10.33.65.159, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  3] local 10.33.65.160 port 46444 connected with 10.33.65.159 port 5001 (icwnd/mss/irtt=14/1448/107)
[  1] local 10.33.65.160 port 46446 connected with 10.33.65.159 port 5001 (icwnd/mss/irtt=14/1448/130)
[  2] local 10.33.65.160 port 46442 connected with 10.33.65.159 port 5001 (icwnd/mss/irtt=14/1448/136)
[  4] local 10.33.65.160 port 46468 connected with 10.33.65.159 port 5001 (icwnd/mss/irtt=14/1448/74)
[ ID] Interval       Transfer     Bandwidth
[  3] 0.0000-10.0142 sec  7.59 GBytes  6.51 Gbits/sec
[  1] 0.0000-10.0142 sec  15.5 GBytes  13.3 Gbits/sec
[  4] 0.0000-10.0136 sec  7.89 GBytes  6.77 Gbits/sec
[  2] 0.0000-10.0142 sec  14.7 GBytes  12.6 Gbits/sec
[SUM] 0.0000-10.0018 sec  45.6 GBytes  39.2 Gbits/sec

Will try with with windows VMs next.

I know it is apples and oranges, but i would accept speed difference of abbout 10-20%.
Here, we are talking about more tahn 600% difference.

@olivierlambert said in Epyc VM to VM networking slow:

Also, about comparing to KVM doesn't make sense at all: there's no such network/disk isolation in KVM, so you can do zero copy, which will yield to much better performances (at the price of the thin isolation).

Yes, we are all aware of KVM / Xen differences, BUT: there is something important here to consider: I am getting similar result in Winsows VM to VM network traffic on Prox and XCP-ng. This proves that network/disk isolation on XCP-ng isn't slowing anything down.

Prox/KVM Linux VM to VM network speed is the same as with Windows VMs.

Problem is much slower network traffic on Linux VM to VM on single XCP-ng host.

Today, i got my hands on HPE ProLiant DL325 Gen10 server with Epyc 7502 32 core (64 threads) CPU. I have installed XCP-ng 8.2.1, and applied all pathes wth yum update. Installed 2 Debian and 2 Windows 10 VMs. Results are very similar:

Linux to Linux VM on single host: 4 Gbit/sec on single thread, max 6 Gbit/sec on mulčtiple threads.
I have tried various amountss of VCPU (2,4,8.12,16) and various combinations of iperf threads.

Windws to Windows VM: 3.5 Gbit/sec on single thread, and 18 Gbit/sec um multiple threads.

All this was with default bios settings, just changed to legacy boot.
Wet performance tuning in bios (c states and other settings), i believe i can get 10-15% more, i will try that tommorow.

So, i think this confirms that this is not Supermicro related problem, but something on relation Xen (hypervisor?) <-> AMD CPU.

@olivierlambert said in XCP-ng not booting when IPMI host interface is disabled on Supermicro H12 board:

Okay worth trying with an installed 8.3 to see if you still have the crash. Don't forget to update it.

Sorry, I didn't had time to test it with 8.3, but i applied October 2023 at friday, and after that XCP-ng boots normaly, with or without IPMI host interface.

@JamesG said in Epyc VM to VM networking slow:

@Danp That's interesting...

Yes, it is, but as i wrote earlier, i get full 21 Gbps Linux VM to VM on Proxmox/KVM (on exact same host, same BIOS settings), so i think it must be some problem on relation Epyc - Xen hypervisor....

@JamesG said in Epyc VM to VM networking slow:

@nicols give me your VM specs and I'll run the exact same tests. vCPU, RAM, anything else relevant.

Debian 12: 16 VCPU, 2GB RAM
Windows 10 pro: 16 VCPU, 8GB RAM, citrix vmtols 9.3.1

On Linux Debian there is no much difference between 8 and 16 VCPU
On Windows 10, 8 VCPU: 16 Gbit/sec, 16 VCPU: 21 Gbit/sec

@nicols said in Epyc VM to VM networking slow:

@nicols said in Epyc VM to VM networking slow:

@JamesG said in Epyc VM to VM networking slow:

@olivierlambert With a billion threads.

nope, Win 10 VM with 4 or 8 VCPU and 8GB RAM
But, with billion threads in Linux VM, speed increases up to 8 threats, then it drops again.

This is with 1 and 16 threads:

https://nextcloud.openit.hr/s/BYGK2yjQziEMKww

also, this:
https://nextcloud.openit.hr/s/CptZpTt4jbWcRPX
is cpu load on host during 2 VM linux doing 16 thread iperf (with cumulative speed of pathetic 4 Gbit/sec).
It seems way to high for this kind of job?

@nicols said in Epyc VM to VM networking slow:

@JamesG said in Epyc VM to VM networking slow:

@olivierlambert With a billion threads.

nope, Win 10 VM with 4 or 8 VCPU and 8GB RAM
But, with billion threads in Linux VM, speed increases up to 8 threats, then it drops again.

This is with 1 and 16 threads:

https://nextcloud.openit.hr/s/BYGK2yjQziEMKww

@JamesG said in Epyc VM to VM networking slow:

@olivierlambert With a billion threads.

nope, Win 10 VM with 4 or 8 VCPU and 8GB RAM
But, with billion threads in Linux VM, speed increases up to 8 threats, then it drops again.

@JamesG said in Epyc VM to VM networking slow:

I've got Supermicro H12SSL boards with 7302p processors. I don't have all the memory slots populated so memory throughput isn't as good as it could be, but it sounds like other people are having a similar experience to me.

That said...My nearly 12 year-old Xeon E3-1230v2 server crushes the Epyc in guest to guest traffic. Quick test:

Guest to Guest traffic is seemingly really impaired compared to the old Xeons.

Finally someone with similar experience, i was starting to think i am a bit crazy

There was update of xen hypervisor today, i will do another test....

@olivierlambert said in XCP-ng not booting when IPMI host interface is disabled on Supermicro H12 board:

Testing with 8.3 (just to boot) will confirm (or not) that the issue might be fixed with a more 8.2 ISO we can generate. So it's just to test so far

Installer always boots, 8.2.1 and 8.3, with or without IPMI host interface. I will try to install 8.3 to another disk tomorrow.

@olivierlambert said in XCP-ng not booting when IPMI host interface is disabled on Supermicro H12 board:

Have you tried to boot with 8.3 beta ISO to see if it's better?

No, only with 8.2.1. I need to go to production with this ASAP, do you have info when will 8.3 be officially released?

I have Supermicro H12 system with H12DSi-N6 MBO (dual socket AMD Epyc).
If I disable IPMI HOST interface in IPMI settings, XCPng crashes on boot (i don't know exact point, at the end of booting hypervisor or when starting to boot dom0). It reboots and i am stuck in boot loop.

With host interface enabled, i have usb0 network in XCP-ng.

Is there any way to disable this IPMI host interface?

From Supermicro FAQ:

Host interface is a new BMC in-band communication protocol that was introduced in Supermicro X12 and H12 motherboards. It is using http secure connection to communicate between the host system and BMC internally through USB port. If you disabled the host interface, the system will be revert to KCS for communication between host and BMC.

@olivierlambert said in Epyc VM to VM networking slow:

Do you have tools and PV drivers installed in Windows? Which version of the tools?

citrix vm tools 9.3.1 are instaleld

@olivierlambert said in Epyc VM to VM networking slow:

You mean 2x Windows VMs (which versions?) on the same EPYC host running XCP-ng, you got 18G with multiple threads (how many?) vs Linux in the same configuration (which kernel/distro? same VM cores & memory?), right?

yes, 2 x win10 pro, on same host, 8-12 multiple threads vs debian 12, same cpu/memory configurations, also 8-12 multiple threads.