From owner-freebsd-virtualization@FreeBSD.ORG Fri Apr 10 23:27:10 2015 Return-Path: Delivered-To: freebsd-virtualization@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 451DC666 for ; Fri, 10 Apr 2015 23:27:10 +0000 (UTC) Received: from mail-wi0-f170.google.com (mail-wi0-f170.google.com [209.85.212.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id CF7AB7E9 for ; Fri, 10 Apr 2015 23:27:09 +0000 (UTC) Received: by wizk4 with SMTP id k4so12613020wiz.1 for ; Fri, 10 Apr 2015 16:27:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-type; bh=I0o5NJctYqE7Y7E53pT4GXBigzHe9BOnBASbRH0ZwPU=; b=cdBxbfAZ78gn7g8rZd4wQgtb5UXHfE14t5XHuBsvbvx9cz3DEZlu0GwXZOL8esQ50U GeDt3QV44zS/Iodh7JZJSPak05PTaVZC2tPlKu+788si0i4CwERO0JGPXSH98oNbpb6c f0EioMtS5CIQH5qHpGFGWk7tOuTgF+d6wVL1bBGtthHXuhx9hAJzoYTvw006sLl2+vTS /m7jYvQosRTG4qJ7j0uZCiORuuYZUBdVLaqAqA0tMHWAI9Sm/+PNA6M90rLHuVwimgPW EWWArB/Cop/lYQbvWaMtU2UvMQ6wQjLJRS62edMZbnryj8WzsPxHBM620uZ6r6EcPqLI GyZw== X-Gm-Message-State: ALoCoQk3AL2F8/AtZioCeWvDbA5OW5lmwMCH9you0eu5u7qIukvv8NOQ3ml3rCs8ck9VycQ7KTW/ X-Received: by 10.194.77.44 with SMTP id p12mr7154820wjw.1.1428708422263; Fri, 10 Apr 2015 16:27:02 -0700 (PDT) MIME-Version: 1.0 Received: by 10.28.97.135 with HTTP; Fri, 10 Apr 2015 16:26:42 -0700 (PDT) In-Reply-To: References: <552809F4.6070206@redbarn.org> <552810CE.7020502@redbarn.org> <5528115B.7060509@freebsd.org> From: Bryan Venteicher Date: Fri, 10 Apr 2015 18:26:42 -0500 Message-ID: Subject: Re: bhyve clock problem, solved by kern.timecounter.hardware="TSC-low" in /etc/sysctl.conf To: Ryan Stone Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 Cc: "freebsd-virtualization@freebsd.org" , Allan Jude X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.18-1 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: Fri, 10 Apr 2015 23:27:10 -0000 On Fri, Apr 10, 2015 at 4:36 PM, Ryan Stone wrote: > Using the TSC as the default timecounter in a VM is dangerous. On some > hardware, the TSC is not synchronized across all CPU cores. This means > that if a VM migrates from one core to another, it could see the > timecounter value go backwards. Time jumping backwards can cause all kin= ds > of hilarity. > > What's really needed is for bhyve to support KVM clock or a similar schem= e > (brianv@ might also still need to commit the guest side of KVM clock as > well). > =E2=80=8BI still need to after addressing some review comments first, but I= 've been perpetually busy with my job. I hope to get to it RealSoon.=E2=80=8B _______________________________________________ > freebsd-virtualization@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > To unsubscribe, send any mail to " > freebsd-virtualization-unsubscribe@freebsd.org" >