Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754814AbZLVTkH (ORCPT ); Tue, 22 Dec 2009 14:40:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754196AbZLVTkE (ORCPT ); Tue, 22 Dec 2009 14:40:04 -0500 Received: from x35.xmailserver.org ([64.71.152.41]:42390 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754478AbZLVTkB (ORCPT ); Tue, 22 Dec 2009 14:40:01 -0500 X-AuthUser: davidel@xmailserver.org Date: Tue, 22 Dec 2009 11:39:55 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@makko.or.mcafeemobile.com To: Gregory Haskins cc: Avi Kivity , Ingo Molnar , kvm@vger.kernel.org, Andrew Morton , torvalds@linux-foundation.org, "linux-kernel@vger.kernel.org" , netdev@vger.kernel.org, "alacrityvm-devel@lists.sourceforge.net" Subject: Re: [GIT PULL] AlacrityVM guest drivers for 2.6.33 In-Reply-To: <4B311ADA.4000700@gmail.com> Message-ID: References: <4B1D4F29.8020309@gmail.com> <20091218215107.GA14946@elte.hu> <4B2F9582.5000002@gmail.com> <20091222075742.GB26467@elte.hu> <4B3103B4.4070708@gmail.com> <4B3115C1.4070303@redhat.com> <4B311ADA.4000700@gmail.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1334 Lines: 39 On Tue, 22 Dec 2009, Gregory Haskins wrote: > On 12/22/09 1:53 PM, Avi Kivity wrote: > > I asked why the irqfd/ioeventfd mechanisms are insufficient, and you did not reply. > > > > BTW: the ioeventfd issue just fell through the cracks, so sorry about > that. Note that I have no specific issue with irqfd ever since the > lockless IRQ injection code was added. > > ioeventfd turned out to be suboptimal for me in the fast path for two > reasons: > > 1) the underlying eventfd is called in atomic context. I had posted > patches to Davide to address that limitation, but I believe he rejected > them on the grounds that they are only relevant to KVM. I thought we addressed this already, in the few hundreds of email we exchanged back then :) > 2) it cannot retain the data field passed in the PIO. I wanted to have > one vector that could tell me what value was written, and this cannot be > expressed in ioeventfd. Like might have hinted in his reply, couldn't you add data support to the ioeventfd bits in KVM, instead of leaking them into mainline eventfd? - Davide -- 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/