From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [v3 12/15] vmx: posted-interrupt handling when vCPU is blocked Date: Thu, 2 Jul 2015 12:09:52 +0200 Message-ID: <1435831792.25170.440.camel@citrix.com> References: <1435123109-10481-1-git-send-email-feng.wu@intel.com> <1435123109-10481-13-git-send-email-feng.wu@intel.com> <55926B62.1000605@citrix.com> <1435757162.25170.354.camel@citrix.com> <1435825820.25170.416.camel@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============9015086304076834937==" 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: "Wu, Feng" Cc: "Tian, Kevin" , "keir@xen.org" , "george.dunlap@eu.citrix.com" , Andrew Cooper , "xen-devel@lists.xen.org" , "jbeulich@suse.com" , "Zhang, Yang Z" List-Id: xen-devel@lists.xenproject.org --===============9015086304076834937== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-9tPfh95k2r4jTfzvlkfl" --=-9tPfh95k2r4jTfzvlkfl Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2015-07-02 at 08:58 +0000, Wu, Feng wrote: > > -----Original Message----- > > From: Dario Faggioli [mailto:dario.faggioli@citrix.com] > > > > This is the third time that I ask: > > (1) whether it is possible to have more vcpus queued on one pcpu PI > > blocked list with desc.on (I really believe it is); >=20 > I think it is, please see the following scenario: >=20 > When cpu masks the interrupts, and an external interrupt occurs for the > assigned device while the target vCPU2 is blocked, the wakeup notificatio= n > event handler has no chance to run, after a while, another wakeup > notification event for vCPU4 blocking on the same pCPU occurs, > after cpu unmakes the interrupts, wakeup notification handler > gets called. Then we get: > vCPU2, desc.on =3D 1 and vCPU4, desc.on =3D 1 > Then in the handler we need to kick both of them. >=20 Ok, first of all, thanks for answering! :-) And yes, this makes sense. > > (2) if yes, whether it is TheRightThing(TM) to kick all of them, as > > soon as any notification arrives, instead that putting together a > > mechanism for kicking only a specific one. > >=20 > Why can't we kick all of them, 'desc.on =3D 1' means there is a pending > interrupt, when we meet this condition, kicking the related vCPU should > be the right thing to do. >=20 Right, I see it now. I felt like I was missing something, and that's why I was asking to you to elaborate a bit more. Thanks again for having done this. I was missing/forgetting half of the way desc.on is actually handled, sorry for this. BTW, I'm finding it hard reading this series from the archives; there appears to be some threading issues and some missing messages. I also don't have it in my inbox, because my filters failed to spot and flag it properly. If you send a new version, please, Cc me, so it will be easier for me to look at all the patches, and provide a more helpful review. Thanks 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) --=-9tPfh95k2r4jTfzvlkfl 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 iEYEABECAAYFAlWVDfEACgkQk4XaBE3IOsSEQACfYWLrFPKK5Gtobu54QImFGXOz jvoAoJUas9JIegZptNziubm6gpOP78Yj =f1hH -----END PGP SIGNATURE----- --=-9tPfh95k2r4jTfzvlkfl-- --===============9015086304076834937== 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 --===============9015086304076834937==--