From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754003Ab1LMKeL (ORCPT ); Tue, 13 Dec 2011 05:34:11 -0500 Received: from mx1.redhat.com ([209.132.183.28]:10766 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751380Ab1LMKeF (ORCPT ); Tue, 13 Dec 2011 05:34:05 -0500 Message-ID: <4EE72A0C.7020401@redhat.com> Date: Tue, 13 Dec 2011 12:33:48 +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> <4EE645B0.9090501@redhat.com> <1323714698.1428.299.camel@jaguar> In-Reply-To: <1323714698.1428.299.camel@jaguar> 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 08:31 PM, Pekka Enberg wrote: > On Mon, 2011-12-12 at 20:19 +0200, Avi Kivity wrote: > > 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. > > No interrupts. I was simply trying to measure PIO overhead to see how > bad the 15 usec per character Ingo measured really is. Yeah. Anyway, uart serial is never going to be fast. That's what virtio-serial is for. -- error compiling committee.c: too many arguments to function