From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [RFC] More efficient RTDS scheduler for Xen 4.6 Date: Mon, 23 Feb 2015 14:50:12 +0000 Message-ID: <1424703009.5819.23.camel@citrix.com> References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============5761473273487858513==" Return-path: Received: from mail6.bemta5.messagelabs.com ([195.245.231.135]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YPuKs-0005VQ-83 for xen-devel@lists.xenproject.org; Mon, 23 Feb 2015 14:50:14 +0000 In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "dgolomb@seas.upenn.edu" Cc: Wei Liu , Ian Campbell , "xisisu@gmail.com" , "mengxu@cis.upenne.edu" , Ian Jackson , "chaowang@wustl.edu" , George Dunlap , "xen-devel@lists.xenproject.org" , "sokolsky@cis.upenn.edu" , "linhphan@cis.upenn.edu" , "xumengpanda@gmail.com" , "cdgill@cse.wustl.edu" , "lichong659@gmail.com" , "lu.wustl@gmail.com" , "lee@cis.upenn.edu" List-Id: xen-devel@lists.xenproject.org --===============5761473273487858513== Content-Language: en-US Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-Crx7fXhoufX5QoHrSHAb" --=-Crx7fXhoufX5QoHrSHAb Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sun, 2015-02-22 at 00:31 -0500, Dagaen Golomb wrote: > Hello everyone, > Hello, > I'd like to solicit comments on improvements to the RTDS scheduler for > Xen 4.6. > My first comment is that I'm happy that you guys are working on this! :-) > [Motivation] >=20 > This change will increase the efficiency of the scheduler by > eliminating invocations when no scheduling decision will be made. The > scheduler is currently ran every 1 millisecond. If no tasks have > terminated or budgets been depleted/replenished since the last > scheduling, no changes will be made. Due to this, the scheduler is > currently called at times when no new action will be taken, wasting > processing resources. With the vital role that the scheduler plays and > the frequency at which it is invoked, this design shift is a > relatively important improvement. > I don't have much to say about this: I'm the one that suggested to go for this approach, and I still think it is a goog idea... Looking forward to see it implemented. The only possible problem that comes to my mind is the need for a lot of timers. How many, it will depend on the actual implementation. Using fewer timer(s) would mean less overhead, but more issues on the event queue(s). The only way, I think, we have is just to get down and implement one solution and see how fast it runs, and whether there are overhead/scalability issue s(and address them at that time, if it will be the case). Regards, Dario --=-Crx7fXhoufX5QoHrSHAb 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 iEYEABECAAYFAlTrPiIACgkQk4XaBE3IOsRJhQCeLvrN73kaikk/pX51KG2iOrg+ 31YAniN9OdIf0LKLlnPie4cNIlBGYLR2 =von4 -----END PGP SIGNATURE----- --=-Crx7fXhoufX5QoHrSHAb-- --===============5761473273487858513== 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 --===============5761473273487858513==--