From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH v3 1/4] xen: add real time scheduler rtds Date: Mon, 22 Sep 2014 19:11:28 +0200 Message-ID: <1411405888.4116.12.camel@Solace.lan> References: <1410730649-2417-1-git-send-email-mengxu@cis.upenn.edu> <1410730649-2417-2-git-send-email-mengxu@cis.upenn.edu> <541B038D.4030307@eu.citrix.com> <1411063714.3531.194.camel@Solace.lan> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6511273463890774659==" 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: Ian Campbell , Sisu Xi , Stefano Stabellini , George Dunlap , Chenyang Lu , Ian Jackson , "xen-devel@lists.xen.org" , Linh Thi Xuan Phan , Meng Xu , Jan Beulich , Chao Wang , Chong Li , Dagaen Golomb List-Id: xen-devel@lists.xenproject.org --===============6511273463890774659== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-YRzbjE02B402Dez5HrxM" --=-YRzbjE02B402Dez5HrxM Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On ven, 2014-09-19 at 09:11 -0400, Meng Xu wrote: > 2014-09-18 14:08 GMT-04:00 Dario Faggioli : > > Actually, what you're saying about the budget, points at another lack o= f > > the current implementation, i.e., payback for budget overrun (also > > mentioned in the same email, I think). That basically means, in the cas= e > > you're describing, recognizing that the vcpu in question overran, by > > allowing its budget to go negative, and making it pay a price for the > > budget to become positive again, in terms on how far its deadline will > > be set (this can be implemented quite easily, by slightly changing the > > while loop we were discussing above). >=20 > Hmm, I think we have other ways to pay a price for the overrun budget. > For example, we can reduce the budget from its next period to pay for > the overrun budget in the current period if it overruns. When we add > timers and avoid such MILLISECS(1) scheduling quantum, the overrun > budget should not be too much, IMO. But anyway, this is something in > the future to solve because it needs to incorporate the extra timers > we will add in the future. >=20 Just FTR, we're talking about the same thing. In fact, I of course meant that overrun must be payed in terms of less than full budget in the following period. The point is, what it the overuun excedes the budget? That's when the "pushing the deadline ahead" comes into play. Say we have a 40ms budget vcpu that it (somehow) manages tor run for 90ms, going down to -50ms. If you push the deadline one period ahead, and gives it a recharge of 40ms (i.e., it's full budget), that will leave it with -10ms. What I was saying was, in this case, we give it another 40ms recharge, but at the price of having its deadline one more period ahead. Anyway, that's for future development, as we agreed. Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-YRzbjE02B402Dez5HrxM 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 v2 iEYEABECAAYFAlQgWEEACgkQk4XaBE3IOsTiewCdHiaINEd7BP9VMfFw1OYHGKje KhcAmgIbp9hkzSg0WSw1ec8QV0JKFBF1 =4qqe -----END PGP SIGNATURE----- --=-YRzbjE02B402Dez5HrxM-- --===============6511273463890774659== 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 --===============6511273463890774659==--