From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38999) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZQ0oi-0004HX-K6 for qemu-devel@nongnu.org; Thu, 13 Aug 2015 18:17:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZQ0of-0001pO-DL for qemu-devel@nongnu.org; Thu, 13 Aug 2015 18:17:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53341) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZQ0of-0001oA-82 for qemu-devel@nongnu.org; Thu, 13 Aug 2015 18:17:41 -0400 Date: Thu, 13 Aug 2015 19:16:50 -0300 From: Marcelo Tosatti Message-ID: <20150813221650.GA8109@amt.cnet> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] about the patch kvmclock Ensure proper env->tsc value for kvmclock_current_nsec calculation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Li, Liang Z" Cc: Paolo Bonzini , "qemu-devel@nongnu.org" On Thu, Aug 13, 2015 at 01:25:29AM +0000, Li, Liang Z wrote: > Hi Paolo & Marcelo, > > Could please point out what issue the patch 317b0a6d8ba44e try to fix? I found in live migration the cpu_synchronize_all_states will be called twice, and it will take more than 1 ms sometimes. I try to do some optimization but lack the knowledge about the background. What the code in 317b0a6d8ba44e requires is to retrieve the TSC value from the kernel. Perhaps you can trace kvm_arch_get_regs and look why its taking that amount of time and what can be done to improve it.