From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: xen 4.5.0 rtds scheduler perform poorly with 2vms Date: Tue, 1 Dec 2015 09:59:42 +0100 Message-ID: <1448960382.7833.307.camel@citrix.com> References: <1448410554.7833.119.camel@citrix.com> <1448644982.7833.290.camel@citrix.com> <1448814429.7833.303.camel@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1079896336678672797==" Return-path: In-Reply-To: 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 Cc: "Yu-An(Victor) Chen" , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org --===============1079896336678672797== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-phnmeDtI4dEyfblH7V9u" --=-phnmeDtI4dEyfblH7V9u Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sun, 2015-11-29 at 11:44 -0500, Meng Xu wrote: > 2015-11-29 11:27 GMT-05:00 Dario Faggioli > : > >=C2=A0 > > Mmmm... As I said many times, I don't remember much of all those RT > > schedulability formulas, but, is really that simple? >=20 > Ah, let me clarify... > It is not that simple. ;-) I just simplify it, hoping it can simplify > the problem and highlight the possible reason. >=20 Ok, glad to know I haven't completely lost my mind, or anything like that! :-) > > I mean, if the in- > > guest scheduling algorithm is global (e.g., global-EDF), the task > > could > > migrate, couldn't it? >=20 > Yes. If these partial VCPUs happen to be scheduled "sequentially", > the > OS inside VM can migrate the task and make the task keep running. But > that is not the worst-case for the OS. >=20 Right, I see it now, and (FWIW) I absolutely agree with the worst-case analysis you provided (thanks). I did not get the fact that you were talking about the worst-case, sorry for the noise. :-D > The detailed illustration of the worst case scenario is at Arvind's > paper: http://link.springer.com/article/10.1007%2Fs11241-009-9073-x > My latest journal paper > (http://link.springer.com/article/10.1007%2Fs11241-015-9223-2) > tighten > the resource supply bound function of the MPR model. I believe the > equations are too boring to most of people in the mailing list. >=20 > So let's avoid the complex equations here. ;-) >=20 Thanks for this too! :-) Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-phnmeDtI4dEyfblH7V9u 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 iEYEABECAAYFAlZdYX8ACgkQk4XaBE3IOsTDTgCfYDH/ljL4PYJTvh5EeNyySQjO oLYAn29HKsyJFU/1jhNtMfsH6HCznCl7 =iMXY -----END PGP SIGNATURE----- --=-phnmeDtI4dEyfblH7V9u-- --===============1079896336678672797== 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 --===============1079896336678672797==--