From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory Haskins Subject: Re: [KVM PATCH 1/2] KVM: Directly inject interrupts via irqfd Date: Thu, 22 Oct 2009 11:33:03 -0400 Message-ID: <4AE07B2F.2040508@gmail.com> References: <20091021143042.14955.22470.stgit@dev.haskins.net> <20091021143453.14955.80578.stgit@dev.haskins.net> <20091021152621.GR29477@redhat.com> <4ADF2A1B.3010205@gmail.com> <20091021153640.GS29477@redhat.com> <4ADF2BDD.40706@gmail.com> <4AE07541.8060903@redhat.com> <4AE076E0.7030100@gmail.com> <4AE07814.6020906@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigBE0F6C12684A324E5F4616DB" Cc: Gleb Natapov , Gregory Haskins , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, alacrityvm-devel@lists.sourceforge.net To: Avi Kivity Return-path: Received: from mail-qy0-f194.google.com ([209.85.221.194]:42950 "EHLO mail-qy0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756257AbZJVPdM (ORCPT ); Thu, 22 Oct 2009 11:33:12 -0400 In-Reply-To: <4AE07814.6020906@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigBE0F6C12684A324E5F4616DB Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Avi Kivity wrote: > On 10/22/2009 05:14 PM, Gregory Haskins wrote: >> Yeah, I was thinking about that after I initially responded to Gleb. >> >> I am thinking something along these lines: >> >> Provide a function that lets you query a GSI for whether it supports >> LOCKLESS or not. Then we can either do one of two things: >> >> 1) Check for the LOCKLESS attribute at irqfd registration, fail if not= >> present >> =20 >=20 > This is the most practical path and leads to the smallest code. Howeve= r > it has the deficiency of exposing internal implementation details to > userspace. In theory userspace could use msi and edge-triggered > pic/ioapic interrupts equally well, it shouldn't have to know that we > didn't bother to lockfree ioapic/pic. >=20 >> 2) Cache the LOCKLESS attribute in the irqfd structure, and either go >> direct or defer to a workqueue depending on the flag. >> =20 >=20 > While this leads to larger code, it is more consistent. >=20 Yeah, I think you are right. Consider these two patches retracted, and I will rewrite it with this concept in place. Kind Regards, -Greg --------------enigBE0F6C12684A324E5F4616DB 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/ iEYEARECAAYFAkrgey8ACgkQP5K2CMvXmqFVlACfWe0ZVNURu+I8jtJkRBS2w91T bxYAnA4cV+jB8541HR0vzs0RQLQ9hgIn =QfaY -----END PGP SIGNATURE----- --------------enigBE0F6C12684A324E5F4616DB--