From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: Xen credit scheduler question Date: Fri, 16 Nov 2012 00:17:58 +0100 Message-ID: <1353021478.5351.68.camel@Solace> References: <50A53479.5050901@eu.citrix.com> <27449f60-0433-4e5f-b1fb-06914b84c6f1@default> <50A54815.9010402@eu.citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0459434827073375237==" Return-path: In-Reply-To: <50A54815.9010402@eu.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: George Dunlap Cc: "xen-devel@lists.xen.org" , Ashok Aletty , Michael Palmeter List-Id: xen-devel@lists.xenproject.org --===============0459434827073375237== Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-Wa8XFbVtXYwrDtKo9HkB" --=-Wa8XFbVtXYwrDtKo9HkB Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2012-11-15 at 19:52 +0000, George Dunlap wrote: >=20 > BTW, are you familiar with Xen's cpupool functionality? The guys at > Fujitsu wrote it so that a customer could rent a fixed number of cores > to a customer, who could then run as many VMs on those cores as they > wanted. I think licensing restrictions had something to do with that > as well. More about that here, if you're interested: > http://blog.xen.org/index.php/2012/04/23/xen-4-2-cpupools/ > That is true, and I was right about to suggest considering cpupools for this discussion. However, since it seems you're interested in the difference between 'core' and 'hyperthread', cpupools also see hyperthreads as cpus (as almost every other piece of Xen, with the only exception of that small bit of the load balancer, as explained by George). So, if cpu0 and cpu1 are hyperthreads of the same core, and you put them in the same pool, you're back to square 1 and you've got to take the 0.7 factor into account. It is probably possible to differentiate, during accounting, the time spent on a (busy?) hyperthread wrt the time spent on a "regular" core, but not without modifying the scheduler. Otherwise, if HT is disturbing too much, I've seen people turning it off (different scope and purposes, i.e., real-time, but still), provided the BIOS offers such an option. Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://retis.sssup.it/people/faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-Wa8XFbVtXYwrDtKo9HkB 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 v1.4.12 (GNU/Linux) iEYEABECAAYFAlCleCYACgkQk4XaBE3IOsRJCgCfbpT7u/11vOC9cQJsqXpH2K5G 2uYAn0Te0vsRqdBzF+FgKcuj7cQ9Othz =cJk/ -----END PGP SIGNATURE----- --=-Wa8XFbVtXYwrDtKo9HkB-- --===============0459434827073375237== 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 --===============0459434827073375237==--