From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [RFC 0/5] xen/arm: support big.little SoC Date: Wed, 21 Sep 2016 17:00:34 +0200 Message-ID: <1474470034.4393.245.camel@citrix.com> References: <1474325742.4393.78.camel@citrix.com> <1474332846.4393.153.camel@citrix.com> <20160920100331.GB8084@linux-u7w5.ap.freescale.net> <4c52141f-a6a4-a0b1-dced-f799b592481e@arm.com> <61196660-df7c-7324-2fb6-cfb11f44ea1e@arm.com> <20160921083800.GA2140@linux-u7w5.ap.freescale.net> <40442b31-c9d6-a130-1589-29a93dfef029@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============5971578669215519989==" Return-path: In-Reply-To: <40442b31-c9d6-a130-1589-29a93dfef029@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: George Dunlap , Peng Fan , Stefano Stabellini Cc: Juergen Gross , Peng Fan , George Dunlap , Andrew Cooper , "xen-devel@lists.xen.org" , Julien Grall , Jan Beulich List-Id: xen-devel@lists.xenproject.org --===============5971578669215519989== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="=-ZKeV4GPO6lTwkg10gCCC" --=-ZKeV4GPO6lTwkg10gCCC Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2016-09-21 at 10:22 +0100, George Dunlap wrote: > On 21/09/16 09:38, Peng Fan wrote: > > User may change the hard affinity of a vcpu, so we also need to > > block a little > > vcpu be scheduled to a big physical cpu. Add some checking code in > > xen, > > when chaning the hard affnity, check whether the cap of a vcpu is > > compatible > > with the cap of the physical cpus. >=20 Yes, restricting affinity changes would indeed will be necessary. Note that this is not a limit of the 'pinning based' implementation. Even if/when we'll have in-scheduler support, trying to pin a LITTLE vcpu to a big pcpu should, AFAIUI, will have to fail. I was thinking to some parameter, that we can set from xl (applicable also = on non-big.LITTLE or non-heterogeneous configurations), for askting Xen to = make the hard-affinity 'immutable'. That would be rather simple to do. But I like Peng's idea of validating hard-affinity against the class even b= etter! :-) > Dario, what do we do with vNUMA / soft affinity? >=20 We do nothing actually. I mean, for now, we just accept whatever the user asks, which might well be setting soft, or even hard, affinity of all the domain to a set of nodes when the domain itself does not have any memory. This is actually another case where either immutability or restriction of the changes that we allow to the (soft, in this case) affinity would be useful. I'd always liked to introduce the logic that at least would print a warning is something that looks really bad is being done, but never got down to actually do that. Maybe this will be the chance to improve wrt to 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) --=-ZKeV4GPO6lTwkg10gCCC 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 iQIcBAABCAAGBQJX4qCTAAoJEBZCeImluHPu4rcP/jHcHd7Aq5/j4zmKpM4bQVI6 +0tkw2FPZXv30Aw5dlMYiljp0ERudGSumoYkIl61qYAPGaYzscfzGyt4kGd65PHR 0ksqhZtclb08Ni00fo60yxfj4ku5fNSATJyFZw2T1LLrY+WXdd4b9ua4hwaqBRJN 5Ow/wR6c9z39PsBnu6/HQwTfBMbIp4IBiJtEouJt3TYR/KYcclEsoZpKyBFQg0MU GU0WXABjXce9o+pFVBKv7MOosgwRpkP63pNxK0zkoLeiI3UbW2DukXRZPdyRy04+ mEnynwmgZwWbgK+1eyCndWreDgbLi6/UKRm02z2bzbWHHG3KM8zT4hkqRxcDx8eG yfUsaBFTshByEZLCH6CgUseXMUf/XEBu8k0eTgNRDEL1tBHvxUBPhOFReGKBCisS 1HpwBJRseJh3+JgYqirGQ1PNqpWMZ77pjxQAo8cFQOXxJQUSaA2LtFoeT6EThRN/ 1hHWGLT2IpqK6JIk0bQdmXO2eF5qCNNl6YSoVowA6LZWvmuD6tB5tAqxEb5Yjt+z s9/FaFNfWTsx9jeGARiO3GKV4EN1f/rGFS6+Q8Vdt/vpM07OSbCT4tle1N5oXSd1 dtFAo0/FXUepRxNtfLgRDjf7t3aJ1++ykZx59Ch6gjijzWw2k7/7QB/jGSF8HMMu dV4JXM4hNw6NIJ8E7RIo =fnm3 -----END PGP SIGNATURE----- --=-ZKeV4GPO6lTwkg10gCCC-- --===============5971578669215519989== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwczovL2xpc3RzLnhlbi5v cmcveGVuLWRldmVsCg== --===============5971578669215519989==--