From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753666Ab1LLSUA (ORCPT ); Mon, 12 Dec 2011 13:20:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:30290 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753365Ab1LLST6 (ORCPT ); Mon, 12 Dec 2011 13:19:58 -0500 Message-ID: <4EE645B0.9090501@redhat.com> Date: Mon, 12 Dec 2011 20:19:28 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0 MIME-Version: 1.0 To: Pekka Enberg CC: Ingo Molnar , Thomas Gleixner , LKML , Sasha Levin Subject: Re: [patch 0/3] kvm tool: Serial emulation overhaul References: <20111210132220.083204833@linutronix.de> <20111211103047.GA19299@elte.hu> <20111211155347.GA1297@elte.hu> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12/2011 01:19 PM, Pekka Enberg wrote: > On Sun, Dec 11, 2011 at 5:53 PM, Ingo Molnar wrote: > > Okay, but look at it from another angle: the top output i > > generate is about 300k characters. 5000 msecs to execute it > > means 16 usecs overhead per character - or about 50k cycles - on > > a top of the class x86 CPU. > > I'm seeing 1.5 usecs per character for this little benchmark: > > No interrupts, right? Things look differently with one interrupt per character and none. Try running kvm_stat with your benchmark and with a guest kernel flooding the serial port. -- error compiling committee.c: too many arguments to function