From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: Strange interdependace between domains Date: Tue, 18 Feb 2014 17:47:02 +0100 Message-ID: <1392742022.32038.572.camel@Solace> References: <1646915994.20140213165604@gmail.com> <1392313015.32038.112.camel@Solace> <295276356.20140213222507@gmail.com> <6010385428.20140214120238@gmail.com> <1392398466.32038.334.camel@Solace> <5302191A.3070400@dornerworks.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============3128400476845483721==" Return-path: In-Reply-To: <5302191A.3070400@dornerworks.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: Nate Studer Cc: Simon Martin , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org --===============3128400476845483721== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-Xw9E/NZwkp4KRihc8L6G" --=-Xw9E/NZwkp4KRihc8L6G Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On lun, 2014-02-17 at 09:13 -0500, Nate Studer wrote: > On 2/14/2014 12:21 PM, Dario Faggioli wrote: > > All this to say that, it should be possible to get a bit more of > > isolation, by tweaking the proper Xen code path appropriately, but if > > the amount of interference that comes from two hypethreads sharing > > registers, pipeline stages, and whatever it is that they share, is > > enough for disturbing your workload, then, I'm afraid we never get much > > farther from the 'don't use hyperthread' solution! :-( >=20 > Which, as you say, unfortunately is the solution unless there is some way= to > configure the hardware to eliminate this interference. =20 > Yeah, I know! > If it's any consolation, > the only multi-core ARINC653 implementations I know of have enacted these= two > restrictions: > 1. # of cores enabled =3D # of memory controllers. > 2. Each enabled core must be configured to not share a memory controller= , > cache, registers, etc... >=20 Nice. :-) > It is practically an AMP system at that point, but without these restrict= ions > you can get some unpredictable behavior unless you have some specialized = or > exotic hardware to make things more deterministic. >=20 Sure, when you really need to be serious about isolation, treats are there well before software (whatever is just OS, virt, whatever) comes into play! Thanks for sharing this and Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-Xw9E/NZwkp4KRihc8L6G 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 iEYEABECAAYFAlMDjoYACgkQk4XaBE3IOsTR0gCeKfGBCaBCwRunbEjqU9kalmZc 8sIAn2OeA1lp29zRvWIzSS8nuVlWhMS6 =f4Dm -----END PGP SIGNATURE----- --=-Xw9E/NZwkp4KRihc8L6G-- --===============3128400476845483721== 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 --===============3128400476845483721==--