From owner-freebsd-virtualization@FreeBSD.ORG Sun Feb 2 04:13:16 2014 Return-Path: Delivered-To: freebsd-virtualization@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 647BDF0; Sun, 2 Feb 2014 04:13:16 +0000 (UTC) Received: from mail-pd0-x229.google.com (mail-pd0-x229.google.com [IPv6:2607:f8b0:400e:c02::229]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 2EB4C1990; Sun, 2 Feb 2014 04:13:16 +0000 (UTC) Received: by mail-pd0-f169.google.com with SMTP id v10so5696653pde.14 for ; Sat, 01 Feb 2014 20:13:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=CeT5dBzvE4q7Zb67gwFq0AtNbp1toSKswJi9DL4yDm0=; b=wRpYA+l5Mo0/hugpvXqBJKx0Bt4aWjCJfq3dI33klCyAo7SPGi+lTn08xstXlcOq8K Rigyd3r1juSbmBT7tuLdRqH6UMYjVJZnpfw13tz2zkCSn8JpA6BnigSGp+bh5+vCWgie 4EwlH826Ei6O4AilDmSIRLrfqWyHaWuSkVDZC+g79DqgXRzO7q4fa9Fb60EizOE8PPOt tPzpoNeFUq3okka29rJCQQy8M5n68yBAanOyJUYxQyWyXTlse1vmlhiYx5XjMgKUXDLD uitKIXTeT5VdUJ7OzDNV2ijseVOCiCzv3ScN1zIvo84C3GIXBbHbDmueioiRIg15XqpS I9GQ== MIME-Version: 1.0 X-Received: by 10.66.145.166 with SMTP id sv6mr30104236pab.31.1391314395336; Sat, 01 Feb 2014 20:13:15 -0800 (PST) Received: by 10.68.155.38 with HTTP; Sat, 1 Feb 2014 20:13:15 -0800 (PST) In-Reply-To: <52EDB899.9060703@freebsd.org> References: <52EDB899.9060703@freebsd.org> Date: Sat, 1 Feb 2014 23:13:15 -0500 Message-ID: Subject: Re: some interesting observations on the relative performance of kvm vs. bhyve From: Aryeh Friedman To: Peter Grehan Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.17 Cc: "freebsd-virtualization@freebsd.org" X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 02 Feb 2014 04:13:16 -0000 On Sat, Feb 1, 2014 at 10:16 PM, Peter Grehan wrote: > > I have 1 host that dual boots FreeBSD and Ubuntu 12.04.3 LTS and bhtyve > >> seems to be atleast 3 or 4 times faster with disk I/O then kvm using the >> most stripped down command lines I can come up with. >> > > I'm guessing that the default cache mode for qemu in that release is > "none". You may want to switch it to "writeback", which is what bhyve does > by default (it can be changed with AHCI, see bhyve(8)). > Does this bring up the same power failure scenario issues mentioned in the link you provided? It seems like the only way to get reasonable performance is to be essentially unsafe in guest writes to the host disk? A question does the ability of FreeBSD to be able to better handle power failure in general better then linux (it seems like every time there is a unscheduled reboot on linux it messes up)? This seems to be at odds with my personal observations of bhyve via petitecloud which I routinely very abruptly start/stop (petitecloud's "stop" is nothing more then killing the hyperv and any cleanup needed) and except for the occasional need for a fsck have not had an issue. But it does not seem to be at odds with OpenStack's experience http://docs.openstack.org/admin-guide-cloud/content/ch_introduction-to-openstack-compute.html#section_nova-disaster-recovery-process > Lots of info on the web about Qemu block i/o cache modes e.g. > > > http://pic.dhe.ibm.com/infocenter/lnxinfo/v3r0m0/index.jsp?topic=%2Fliaat% > 2Fliaatbpkvmguestcache.htm > > later, > > Peter. > -- Aryeh M. Friedman, Lead Developer, http://www.PetiteCloud.org