From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [GIT PULL] AlacrityVM guest drivers for 2.6.33 Date: Wed, 23 Dec 2009 23:01:41 +0200 Message-ID: <4B328535.5040105@redhat.com> References: <4B1D4F29.8020309@gmail.com> <87637zdy9g.fsf@basil.nowhere.org> <4B30E654.40702@codemonkey.ws> <200912221701.56840.bzolnier@gmail.com> <4B30F214.80206@codemonkey.ws> <20091223065129.GA19600@elte.hu> <4B3248F9.5030504@gmail.com> <4B327F3A.9020101@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Ingo Molnar , Anthony Liguori , Bartlomiej Zolnierkiewicz , Andi Kleen , kvm@vger.kernel.org, Andrew Morton , torvalds@linux-foundation.org, "linux-kernel@vger.kernel.org" , netdev@vger.kernel.org, "alacrityvm-devel@lists.sourceforge.net" To: Gregory Haskins Return-path: In-Reply-To: <4B327F3A.9020101@redhat.com> Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 12/23/2009 10:36 PM, Avi Kivity wrote: > On 12/23/2009 06:44 PM, Gregory Haskins wrote: >> >>> - Are a pure software concept >> By design. In fact, I would describe it as "software to software >> optimized" as opposed to trying to shoehorn into something that was >> designed as a software-to-hardware interface (and therefore has >> assumptions about the constraints in that environment that are not >> applicable in software-only). >> > > And that's the biggest mistake you can make. Look at Xen, for > instance. The paravirtualized the fork out of everything that moved > in order to get x86 virt going. And where are they now? x86_64 > syscalls are slow since they have to trap to the hypervisor and > (partially) flush the tlb. With npt or ept capable hosts performance > is better for many workloads on fullvirt. And paravirt doesn't > support Windows. Their unsung hero Jeremy is still trying to upstream > dom0 Xen support. And they get to support it forever. > > VMware stuck with the hardware defined interfaces. Sure they had to > implement binary translation to get there, but as a result, they only > have to support one interface, all guests support it, and they can > drop it on newer hosts where it doesn't give them anything. As a twist on this, the VMware paravirt driver interface is so hardware-like that they're getting hardware vendors to supply cards that implement it. Try that with a pure software approach. -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.