From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: What is the target CPU "topology" of an SMP HVM machine? Date: Wed, 14 Aug 2013 22:52:54 +0200 Message-ID: <1376513574.2687.191.camel@Abyss> References: <520BE333.8040201@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6608302376273819374==" Return-path: In-Reply-To: <520BE333.8040201@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: Andrew Cooper Cc: "xen-devel@lists.xen.org" , Keir Fraser , Elena Ufimtseva , Jan Beulich , Eric Shelton List-Id: xen-devel@lists.xenproject.org --===============6608302376273819374== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-u8334VPOwU7SXQxJxe9g" --=-u8334VPOwU7SXQxJxe9g Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On mer, 2013-08-14 at 21:06 +0100, Andrew Cooper wrote: > On 14/08/13 20:23, Eric Shelton wrote: > > So, seeing as this information is being closely interrogated, what is > > the target virtual CPU topology? How should this be reported via > > CPUID and MSR? Darwin appears to be trying to determine or take into > > account things such as a number of packages, dies per package, cores > > per pie & package, and threads/logical CPUs per core & package; the > > degrees of sharing of caches by CPUs at various cache levels, and the > > presence of hyperthreading. >=20 > Xen by default advertises all VCPUs as separate sockets, to try and > dissuade "clever" schedulers from doing dumb things based on false > information. >=20 Are we absolutely sure about this? I'm asking because Elena run into a similar issue, i.e., seeing some vCPUs being advertised as threads/siblings (although that was a pv-guest)... Am I right Elena? I think she also has a patch that she may be able to share soon, which does right the masking of some of the CPUID stuff, as it looks like some false information was reaching out to the Linux Scheduler! :-O I'm not sure this is the exact same issue, though.... Elena, could you tell something more about this? Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-u8334VPOwU7SXQxJxe9g Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (GNU/Linux) iEYEABECAAYFAlIL7iYACgkQk4XaBE3IOsQmkgCfViJwSdV4QrtXIUDUZ8fTkCoB ZP0An2OuzH8MHmqEqIfG0HKcz6k9pUwO =hzaI -----END PGP SIGNATURE----- --=-u8334VPOwU7SXQxJxe9g-- --===============6608302376273819374== 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 --===============6608302376273819374==--