Re: [Xen-devel] Clarification regarding xen toolstack for booting a pv guest

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Aug 10, 2015 at 05:00:51PM -0700, sainath grandhi wrote:
> Hello all,
> 
> 
> 
> I was measuring amount of time taken on host by the Xen toolstack
> while launching a PV guest.
> 
> I notice that there is around 2-3 seconds of time spent on dom0 by
> toolstack before guest starts executing. Significant amount of time is
> taken in the function xc_dom_boot_mem_init, around 2 seconds for a
> guest memory of 2 GB
> 
> This code does allocate guest memory and mappings and amount of time
> this function takes increases proportionally with increasing requested
> guest memory in the guest config file.
> 
> Has anyone noticed similar thing? Is ~2 seconds of wall clock time
> reasonable for guest memory mapping?

I guess it is because Dom0 has to balloon down to free up memory for
guest.

What is your Xen command line? Have you tried putting
dom0_mem=512M,max:512M there?

Wei.

> 
> Thanks
> 
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