Mailing List Archive: Need help with xen boot time

(+ Stefano)

On 13/12/2022 10:16, Talabattula, Viswa Krishna Raveendra wrote:
> [AMD Official Use Only - General]
>
> Hi All,

Hi,

>
> I am Raveendra .Currently I am working on xen hypervisor with Ubuntu 22.04 .Compared to Native ubuntu kernel ,dom0 with xen is taking around 1.8s more to boot.

Can you be a bit more precise on your setup? A few questions to start:

* Is it x86 or Arm?
* If x86, are you using PVH or PV?

If you are using PV then I would expect an higher overhead because the
OS page tables have to be validated by the hypervisor.

> I used system-analyze tool for calculating boot time.

Did your tool indicate any are where the performance are worse compare
to baremeal?

> Can any body publish the boot time of xen that you are observing, also is there anyway to optimize the xen boot time,related to xen build or any command line options.

The boot time (and overhead) will be specific to your HW and
configuration. So I don't think sharing the boot time is useful.

In term of optimization, it will again depend on the setup. If you are
using PV, then possibly switching to PVH will help (bear in mind there
are still some functional gap with PV).

Cheers,

--
Julien Grall