From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: VCPU migration overhead conpensation ? Date: Wed, 10 Apr 2013 10:25:56 +0200 Message-ID: <1365582356.2934.11.camel@Abyss> References: <1365472000.9958.110.camel@Solace> <516520FD.6020100@eu.citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4724342801970981617==" Return-path: In-Reply-To: <516520FD.6020100@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.xensource.com" , Sisu Xi List-Id: xen-devel@lists.xenproject.org --===============4724342801970981617== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-bjifjMsYXoHzGT6f3wJc" --=-bjifjMsYXoHzGT6f3wJc Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On mer, 2013-04-10 at 09:21 +0100, George Dunlap wrote > On 10/04/13 06:44, Sisu Xi wrote: > > I am also performing some overhead measurement for the scheduler. If a= =20 > > VCPU is migrated from one core to another, the overhead is around 2=20 > > microseconds on my machine, which is much less than what is set in=20 > > Credit2 (50 microseconds). >=20 > When you say "overhead", I assume you mean that's how long the whole=20 > migration takes? >=20 > The point of the compensation isn't so much for the actual migration=20 > itself, but for the lower performance the vcpu will get after the=20 > migration due to having cold caches. >=20 Which is, BTW, right the effect that we were trying to measure (although, again, it was Linux, not Xen at that time), with the experiments I was describing in my e-mail... Might have been obvious, but I think it's worth making it even more that (thanks George :-) ), since I agree with George that _this_ is what we should be concerned about, when it comes to migration. Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-bjifjMsYXoHzGT6f3wJc 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 v1.4.13 (GNU/Linux) iEYEABECAAYFAlFlIhQACgkQk4XaBE3IOsS8gwCcC7BtudnCvCN05/InSrVPOs8P GrIAnjCWYO1dMvwLlzkvjcJRD8xADyO6 =h8yS -----END PGP SIGNATURE----- --=-bjifjMsYXoHzGT6f3wJc-- --===============4724342801970981617== 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 --===============4724342801970981617==--