Re: Bad performance with Xen

[Olivier Lambert <lambert.olivier@xxxxxxxxx>]

Hi Agustin,

I just did a test on XCP-ng 8.1 (Xen 4.13) with a fresh Debian 10 VM, and here is the result I have:

```

# time for i in `dpkg -L ncurses-term | sort`; do if [ -f "$i" ]; then ls -ld  "$i"; fi; done | tr -s " "| cut -d" " -f5,9 >/dev/null

real 0m2,741s
user 0m2,248s
sys 0m0,574s

```

My hardware isn't ultra modern: Xeon(R) CPU E3-1225 v5 (3.3Ghz) on a small Dell T30 machine, VM storage on local HDD. I did the test 3 times, and I have always results between 2,6 and 2,8 secs.

Regards,

Olivier.

Le sam. 2 mai 2020 à 18:33, Agustin Lopez <Agustin.Lopez@xxxxx> a écrit :

Hello.


We are testing low performance in IO with the next command in Debian Buster (kernel 4.19.0-8-amd64) with Xen (4.11.4-pre)

        time for i in `dpkg -L ncurses-term | sort`; do if [ -f "$i" ]; then ls -ld  "$i"; fi; done | tr -s " "| cut -d" " -f5,9 >/dev/null


In all our Dom0s - DomUs  we are getting around 20 seconds.

In the same physical machines booting with Debian without Xen, we get 5-7 seconds

In some KVM VMs in other server we are geting almost the same as physical.

(all in local Disks. XFS filesystems. Images of DomUs in raw format)


I have booted Xen with 4.8 y 4.4 releases with almost the same bad data.


Where could be the problem?

I think of is not normal this difference between DomUs and physical machine.


Every pointer will be welcomed.


Best regards,

Agustín