From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH v3 for Xen 4.6 3/4] libxl: enable per-VCPU parameter settings for RTDS scheduler Date: Wed, 1 Jul 2015 14:50:28 +0200 Message-ID: <1435755028.25170.330.camel@citrix.com> References: <1435545899-22751-1-git-send-email-chong.li@wustl.edu> <1435545899-22751-4-git-send-email-chong.li@wustl.edu> <1435667216.21469.122.camel@citrix.com> <1435679837.21469.218.camel@citrix.com> <1435681194.21469.223.camel@citrix.com> <1435740482.21469.233.camel@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============3818293749143465520==" Return-path: In-Reply-To: <1435740482.21469.233.camel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Meng Xu , Chong Li Cc: Wei Liu , Ian Campbell , Sisu Xi , George Dunlap , Ian Jackson , xen-devel , Meng Xu , Chong Li , Dagaen Golomb List-Id: xen-devel@lists.xenproject.org --===============3818293749143465520== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-SCM1azdykwjaZzyXDuiw" --=-SCM1azdykwjaZzyXDuiw Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2015-07-01 at 09:48 +0100, Ian Campbell wrote: > On Tue, 2015-06-30 at 17:54 -0700, Meng Xu wrote: > > 2015-06-30 9:19 GMT-07:00 Ian Campbell : > > > Note that this field is not the same as the others in this struct, it= is > > > in effect part of the "key" while the others are the "values". > > > > >=20 > > vcpuid in the libxl is not the key but the value. > >=20 > > When it is passed into hypervisor, vcpuid acts as the key to identify > > which VCPU. vcpuid should be be negative when it is passed to > > hypervisor. > >=20 > > Do you have any concerns about assigning the initial value of vcpuid as= -1? >=20 > libxl needs to do _something_ if it is passed a vcpuid=3D-1. What is that > something? >=20 Exactly. Meng, Chong, maybe what you are missing from Ian's point is the fact that libxl is a library on top of which to build more advanced toolstack, it is not just something that the xl command line tool links to. Therefore, it has to work even when it is not xl that makes the API calls. Actually, I better say that --not only it has to work-- it has to be easy and comfortable to use from high level components different than xl. The outcome of this reasoning is that, you can't just assume that a default value does not matter much, because every code path in _xl_ overrides it. Everything that is in libxl must make sense in libxl per-se, even without bringing xl into the picture. So, in this case, you need to think whether it is convenient _in_general_, not only wrt xl, to have -1 as default value for vcpuid and, if yes, what happens if such default is not overridden and libxl gets to deal with it! Hope this helps... If this was not the issue, sorry for the noise. :-) Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-SCM1azdykwjaZzyXDuiw Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEABECAAYFAlWT4hUACgkQk4XaBE3IOsRO4ACfeSDzg92nMeOouez81tEGG37q mSQAoIqIVbuU1O6TpkYfjrCl1jKL4LYj =Bgat -----END PGP SIGNATURE----- --=-SCM1azdykwjaZzyXDuiw-- --===============3818293749143465520== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel --===============3818293749143465520==--