From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH v3 1/7] xen: vNUMA support for PV guests Date: Tue, 19 Nov 2013 16:42:52 +0100 Message-ID: <1384875772.15360.6.camel@Solace> References: <1384806262-12532-1-git-send-email-ufimtseva@gmail.com> <1384806262-12532-2-git-send-email-ufimtseva@gmail.com> <528B7D350200007800104840@nat28.tlf.novell.com> <1384871712.19880.90.camel@Abyss> <528B885702000078001048CF@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6322174628952634665==" Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1VinSF-00020b-ND for xen-devel@lists.xenproject.org; Tue, 19 Nov 2013 15:43:07 +0000 In-Reply-To: <528B885702000078001048CF@nat28.tlf.novell.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: Jan Beulich Cc: keir@xen.org, Ian.Campbell@citrix.com, lccycc123@gmail.com, george.dunlap@eu.citrix.com, msw@linux.com, stefano.stabellini@eu.citrix.com, ian.jackson@eu.citrix.com, Elena Ufimtseva , xen-devel List-Id: xen-devel@lists.xenproject.org --===============6322174628952634665== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-bUBvYjdsPQV2Dj+sUVqJ" --=-bUBvYjdsPQV2Dj+sUVqJ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On mar, 2013-11-19 at 14:48 +0000, Jan Beulich wrote: > >>> On 19.11.13 at 15:35, Dario Faggioli wrot= e: > > If I understand correctly what you're asking, the (current) answer is i= n > > the Linux patch, here: > >=20 > > =20 > > http://bugs.xenproject.org/xen/mid/%3C1384811922-14642-2-git-send-email= -ufimt=20 > > seva@gmail.com%3E > >=20 > > which uses num_possible_cpus() > >=20 > > http://lxr.linux.no/linux+v3.12/+code=3Dnum_possible_cpus=20 > >=20 > > to size all the three arrays. >=20 > But what guarantees num_possible_cpus() to be larger than some > hypervisor internal variables that the domain has no knowledge > about?=20 > Nothing, I guess. > Just consider a guest with a Linux configured for just 4 > CPUs and 2 nodes, but having a config file specifying 16 vCPU-s on > 4 virtual nodes? >=20 That's a fair point. I can't remember the rationale behind the choice of using num_possible_cpus()... ISTR some very early version (probably not even shared on xen-devel) of the series using something like NR_CPUS, but that would suffer from the same issue, I think. Probably, we just overlooked the situation you're describing and though that, given we don't allow nr_vcpus > nr_vnodes, using num_possible_cpus() ought to be enough. But I see it now. So, what would the best option be? Another hypercall (or a special way of calling this one) "just" to retrieve the number of vnodes? Thanks and Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-bUBvYjdsPQV2Dj+sUVqJ 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 v1.4.15 (GNU/Linux) iEYEABECAAYFAlKLhvwACgkQk4XaBE3IOsQEigCgioBc1YdqLXc2fQfRh+YWc9B5 UGYAn0/Adit0QOMu7ZhuwgTaJDVuHaYz =FViw -----END PGP SIGNATURE----- --=-bUBvYjdsPQV2Dj+sUVqJ-- --===============6322174628952634665== 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 --===============6322174628952634665==--