From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35935) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YBoDE-0002Oo-5w for qemu-devel@nongnu.org; Thu, 15 Jan 2015 12:28:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YBoDA-0002f2-6R for qemu-devel@nongnu.org; Thu, 15 Jan 2015 12:28:04 -0500 Received: from mail-wi0-x231.google.com ([2a00:1450:400c:c05::231]:60149) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YBoD9-0002eb-Vp for qemu-devel@nongnu.org; Thu, 15 Jan 2015 12:28:00 -0500 Received: by mail-wi0-f177.google.com with SMTP id l15so19384426wiw.4 for ; Thu, 15 Jan 2015 09:27:59 -0800 (PST) Sender: Paolo Bonzini Message-ID: <54B7F89A.80107@redhat.com> Date: Thu, 15 Jan 2015 18:27:54 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] kvmclock, Migration, and NTP clock jitter List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mohammed Gamal , qemu-devel@nongnu.org On 15/01/2015 17:39, Mohammed Gamal wrote: > The increase in the jitter and offset values is well within the 500 ppm > frequency tolerance limit, and therefore are easily corrected by > subsequent NTP clock sync events, but some live migrations do cause much > higher jitter and offset jumps, which can not be corrected by NTP and > cause the time to go way off. Any idea why this is the case? It might be fixed in QEMU 2.2. See https://lists.gnu.org/archive/html/qemu-devel/2014-09/msg01239.html Paolo