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Hello.

I detected a problem using the latest kernel 6.1.0.-25-amd64 with all my VMs under Nutanix.

 

I recently upgraded all my Debian servers from version 12.6 to 12.7: in version 12.6 the linux kernel in use was 6.1.0-23-amd64 and in version 12.7 is 6.1.0-25-amd64.

 

The issue is related with the download speed using this kernel in all my upgraded VM’s. It’s extremely slow. So after 2 days trying to figure out what was happening (installing debian 12.7 in a new VM same problem....installing in VirtualBox no problem at all), so I decided to rollback to the old kernel, maintaining the Debian version 12.7 (with kernel 6.1.0-23-amd64) and the problem stopped.

 

I’m using the following system, see picture:

 

 

Here are some speed tests:

 

Debian version 12.6:

wget https://proof.ovh.net/files/100Mb.dat

--2024-09-05 01:26:12-- https://proof.ovh.net/files/100Mb.dat

Resolviendo proof.ovh.net (proof.ovh.net)... 141.95.207.211, 2001:41d0:242:d300::

Conectando con proof.ovh.net (proof.ovh.net)p141.95.207.211]:443... conectado.

...

Grabando a: «100Mb.dat.2»

100Mb.dat.2 100%1=======================>] 100,00M 29,2MB/s en 3,6s

2024-09-05 01:26:16 (28,0 MB/s) - «100Mb.dat.2» guardado .104857600/104857600]

================================================================

Debian versión 12.7:

wget https://proof.ovh.net/files/100Mb.dat

--2024-09-05 01:17:06-- https://proof.ovh.net/files/100Mb.dat

Resolviendo proof.ovh.net (proof.ovh.net)... 141.95.207.211, 2001:41d0:242:d300::

Conectando con proof.ovh.net (proof.ovh.net)h141.95.207.211]:443... conectado.

Petición HTTP enviada, esperando respuesta... 200 OK

Longitud: 104857600 (100M) tapplication/octet-stream]

Grabando a: «100Mb.dat.1»

100Mb.dat.1 2%1==== ] 2,13M 193KB/s eta 7m 35s

================================================================

 

================================================================

Example of speed test of VM running in same node and debian 11.10:

================================================================

Idle Latency: 16.98 ms (jitter: 0.08ms, low: 16.96ms, high: 17.11ms)

Download: 2825.49 Mbps (data used: 3.0 GB)

Upload: 1832.95 Mbps (data used: 3.3 GB)

Result URL: https://www.speedtest.net/result/c/4491d7ea-a293-402f-9597-9b08de9a3846

================================================================

Example of speed test of VM running in same node and debian 12.7 (see Download speed):

================================================================

Download: 8.43 Mbps (data used: 10.1 MB)

Upload: 2281.23 Mbps (data used: 4.0 GB)

Result URL: https://www.speedtest.net/result/c/d1d656ac-5c26-476c-819c-0b9448ca05b3

================================================================

 

Maybe a bug or something with the hypervisor?

 

Thank you.

https://lore.kernel.org/kvm/bug-219129-28872@https.bugzilla.kernel.org%2F/T/#re2e15520e202eca2561837019cf29a9d925f1063

 

Looks to be an issue in the Linux kernel. If you read in there it states a patch release is coming for 6.1 also.


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