Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932082AbZIAQeb (ORCPT ); Tue, 1 Sep 2009 12:34:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753964AbZIAQea (ORCPT ); Tue, 1 Sep 2009 12:34:30 -0400 Received: from mail-ew0-f206.google.com ([209.85.219.206]:34850 "EHLO mail-ew0-f206.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751427AbZIAQe3 convert rfc822-to-8bit (ORCPT ); Tue, 1 Sep 2009 12:34:29 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=qp43p2DWT/Ei39GqZFBWNo+3Cjj9h00jI8wF3+2lVL9fK0yin1AIE6eB1VHKNMvJ7E jfbhS0+o/fMzC+R1VQonyehYPHt1kOHfJgEbk7vE/LJKoNDQwrNyS5QM4LUo6rVfx4f3 Qlhqyq3+cOpgQ+I0Z47CePSzV8aWVT+a7WflI= MIME-Version: 1.0 In-Reply-To: References: <1251415060.16297.58.camel@ank32.eng.vmware.com> <1251739735.16169.20.camel@ank32.eng.vmware.com> <1251741624.18828.83.camel@mulgrave.site> Date: Tue, 1 Sep 2009 18:34:30 +0200 X-Google-Sender-Auth: 8215e5e431a544e5 Message-ID: Subject: Re: [PATCH] SCSI driver for VMware's virtual HBA. From: Bart Van Assche To: Roland Dreier Cc: James Bottomley , akataria@vmware.com, Robert Love , Randy Dunlap , Mike Christie , linux-scsi@vger.kernel.org, LKML , Andrew Morton , Dmitry Torokhov , Rolf Eike Beer , Maxime Austruy Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1789 Lines: 35 On Tue, Sep 1, 2009 at 6:12 PM, Roland Dreier wrote: > ?> - Reuse the ib_ipoib kernel module to provide an IP stack on top of > ?> the new RDMA driver instead of having to maintain a separate network > ?> driver for this hardware (ibmveth). > > I don't think this really makes sense, because IPoIB is not really > handling ethernet (it is a different L2 ethernet encapsulation), and I > think the commonality with ibmveth is going to be minimal. What I had in mind was not to start searching for code shared between the ipoib and ibmveth kernel modules, but to replace the virtual Ethernet layer by IPoIB on top of a new RDMA driver. I'm not sure however this approach would work better than the currently implemented approach in ibmveth. > I'm not really sure we should be trying to force drivers to share just > because they are paravirtualized -- if there is real commonality, then > sure put it in common code, but different hypervisors are probably as > different as different hardware. Agreed. But several people are currently looking at how to improve the performance of I/O performed inside a virtual machine without being familiar with the VIA architecture or the RDMA API. This is a pity because the Virtual Interface Architecture was designed to allow high-throughput low-latency I/O, and has some features that are not present in any other mainstream I/O architecture I know of (e.g. the ability to perform I/O from userspace without having to invoke any system call in the performance-critical path). Bart. -- 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/