Re: [PATCH v2 for Xen 4.6 3/4] libxl: enabling XL to set per-VCPU parameters of a domain for RTDS scheduler

From: Ian Campbell <ian.campbell@citrix.com>
To: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Chong Li <chong.li@wustl.edu>, Wei Liu <wei.liu2@citrix.com>,
	Sisu Xi <xisisu@gmail.com>,
	George Dunlap <george.dunlap@eu.citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	xen-devel <xen-devel@lists.xen.org>,
	Meng Xu <mengxu@cis.upenn.edu>, Chong Li <lichong659@gmail.com>,
	Dagaen Golomb <dgolomb@seas.upenn.edu>
Subject: Re: [PATCH v2 for Xen 4.6 3/4] libxl: enabling XL to set per-VCPU parameters of a domain for RTDS scheduler
Date: Wed, 17 Jun 2015 13:14:34 +0100	[thread overview]
Message-ID: <1434543274.13744.353.camel@citrix.com> (raw)
In-Reply-To: <1434363154.2375.50.camel@citrix.com>

On Mon, 2015-06-15 at 12:12 +0200, Dario Faggioli wrote:
> A parameter is either per-domain or per-vcpu, no matter how the user try
> to set or get it. In RTDS, all parameters are per-domain now and, with
> your work, all of them are becoming per-vcpu, and that's ok. But then,
> per-dom parameters should just no longer exist.

Are you saying there is going to be no domain wide default for a given
per-vcpu parameter? 

if that is the case then what happens if I hotplug a new VCPU without
settings its per-vcpu properties?

I expected something like.

domain_params_set (weight=10)
add vcpu0 (weight will be 10)
add vcpu1 (weight will be 10)
vcpu_params_set(0, weight=20)
add vcpu2 (weight will be 10, from domain wide default)

If not that then what weight should vcpu2 have at this point?

Ian.