Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751691AbWJWHmY (ORCPT ); Mon, 23 Oct 2006 03:42:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751694AbWJWHmY (ORCPT ); Mon, 23 Oct 2006 03:42:24 -0400 Received: from mis011-1.exch011.intermedia.net ([64.78.21.128]:40579 "EHLO mis011-1.exch011.intermedia.net") by vger.kernel.org with ESMTP id S1751691AbWJWHmY (ORCPT ); Mon, 23 Oct 2006 03:42:24 -0400 Message-ID: <453C725A.7080501@qumranet.com> Date: Mon, 23 Oct 2006 03:42:18 -0400 From: Avi Kivity User-Agent: Thunderbird 1.5.0.7 (X11/20060913) MIME-Version: 1.0 To: Alan Cox CC: Arnd Bergmann , Muli Ben-Yehuda , linux-kernel , Anthony Liguori Subject: Re: [PATCH 0/7] KVM: Kernel-based Virtual Machine References: <4537818D.4060204@qumranet.com> <20061019173151.GD4957@rhun.haifa.ibm.com> <4537BD27.7050509@qumranet.com> <200610211816.27964.arnd@arndb.de> <453B2DDB.3010303@qumranet.com> <1161547015.1919.36.camel@localhost.localdomain> In-Reply-To: <1161547015.1919.36.camel@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 23 Oct 2006 07:42:23.0324 (UTC) FILETIME=[C714C9C0:01C6F676] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1447 Lines: 47 Alan Cox wrote: > Ar Sul, 2006-10-22 am 10:37 +0200, ysgrifennodd Avi Kivity: > >> I like this. Since we plan to support multiple vcpus per vm, the fs >> structure might look like: >> > > Three times the syscall overhead is bad for an emulation very bad Why? You would usually just call kvm_run(). get/set regs are not needed normally. > for an > emulation of a CPU whose virtualisation is half baked. > > Blood rare. The thing can't even virtualize the first instruction executed. >> It's certainly a lot more code though, and requires new syscalls. Since >> this is a little esoteric does it warrant new syscalls? >> > > I think not - ioctl exists to avoid adding a billion esoteric one user > syscalls. The idea of a VFS sysfs type view of the running vm is great > for tools however so I wouldn't throw it out entirely or see it as ioctl > versus fs. > I still want a separate object per vcpu: kvm_fd = open("/dev/kvm") for (i = 0; i < n; ++i) vcpu_fds[i] = ioctl(kvm_fd, KVM_CREATE_VCPU, i) so the refcounting doesn't bounce cachelines too much. In effect it's a mini filesystem. -- error compiling committee.c: too many arguments to function - 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/