Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757703AbZFRTEn (ORCPT ); Thu, 18 Jun 2009 15:04:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755260AbZFRTEd (ORCPT ); Thu, 18 Jun 2009 15:04:33 -0400 Received: from victor.provo.novell.com ([137.65.250.26]:47018 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755080AbZFRTEc (ORCPT ); Thu, 18 Jun 2009 15:04:32 -0400 Message-ID: <4A3A8FBC.10905@novell.com> Date: Thu, 18 Jun 2009 15:04:28 -0400 From: Gregory Haskins User-Agent: Thunderbird 2.0.0.21 (Macintosh/20090302) MIME-Version: 1.0 To: Davide Libenzi CC: "Michael S. Tsirkin" , kvm@vger.kernel.org, Linux Kernel Mailing List , avi@redhat.com, paulmck@linux.vnet.ibm.com, Ingo Molnar Subject: Re: [KVM-RFC PATCH 1/2] eventfd: add an explicit srcu based notifier interface References: <20090616022041.23890.90120.stgit@dev.haskins.net> <20090616022956.23890.63776.stgit@dev.haskins.net> <20090616140240.GA9401@redhat.com> <4A37A7FC.4090403@novell.com> <20090616143816.GA18196@redhat.com> <4A37B0BB.3020005@novell.com> <20090616145502.GA1102@redhat.com> <4A37B832.6040206@novell.com> <20090616154150.GA17494@redhat.com> <4A37C592.2030407@novell.com> <4A37CFDA.4000602@novell.com> <4A3927C0.5060607@novell.com> <4A39415C.9060803@novell.com> <4A39649C.4020602@novell.com> <4A3A48AB.2080206@novell.com> In-Reply-To: X-Enigmail-Version: 0.95.7 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig6AECB8376F4617BC9394DD59" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2369 Lines: 63 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig6AECB8376F4617BC9394DD59 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Davide Libenzi wrote: > On Thu, 18 Jun 2009, Gregory Haskins wrote: > > =20 >> Actually there is only one (the tx-thread) aside from the eventfd >> imposed workqueue one. Incidentally, I would love to get rid of the >> other thread too, so I am not just picking on eventfd ;). The other i= s >> a lot harder since it has to update the virtio-ring and may need to pa= ge >> in guest memory to do so. >> =20 > > No, there is the interface rx softirq too, that makes two. Actually, I believe you are mistaken. It normally executes the softirq in interrupt context, not a thread. But I digress. Lets just shelve the SRCU conversation for another day.=20 It was my bad for introducing it now prematurely to solve a mostly unrelated problem: the module-reference thing. I didn't realize the SRCU change would be so controversial, and I didn't think to split things apart as I have done today. But the fact is: I do not see any way to actually use your referenceless POLLHUP release code in a race free way without doing something like I propose in 3/4, 4/4. Lets keep the discussion focused on that for now, if we could. Later, after we get this thing all built, I will re-run the numbers and post some results so that Davide may have better proof that the context switch overhead isn't just lost in the noise. I think that is all he is asking for anyway, which is understandable. Regards, -Greg --------------enig6AECB8376F4617BC9394DD59 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.11 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAko6j7wACgkQlOSOBdgZUxl2SQCfW12+7N2f6y92X0RrvFfCq83q WP0An0pxg0ilTJt2wqJ0nUcUYLfcWfGB =EeWe -----END PGP SIGNATURE----- --------------enig6AECB8376F4617BC9394DD59-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/