From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265119AbUHJNRq (ORCPT ); Tue, 10 Aug 2004 09:17:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265106AbUHJNQu (ORCPT ); Tue, 10 Aug 2004 09:16:50 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:22791 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S265091AbUHJNMa (ORCPT ); Tue, 10 Aug 2004 09:12:30 -0400 Date: Tue, 10 Aug 2004 14:12:20 +0100 From: Russell King To: Ingo Molnar Cc: William Lee Irwin III , V13 , Jesse Barnes , Andrew Morton , linux-kernel@vger.kernel.org, Nick Piggin Subject: Re: 2.6.8-rc3-mm2 Message-ID: <20040810141220.B20890@flint.arm.linux.org.uk> Mail-Followup-To: Ingo Molnar , William Lee Irwin III , V13 , Jesse Barnes , Andrew Morton , linux-kernel@vger.kernel.org, Nick Piggin References: <200408091217.50786.jbarnes@engr.sgi.com> <20040810100234.GN11200@holomorphy.com> <20040810115307.GR11200@holomorphy.com> <200408101552.22501.v13@priest.com> <20040810125140.GU11200@holomorphy.com> <20040810125529.GA22650@elte.hu> <20040810125651.GV11200@holomorphy.com> <20040810130122.GA26326@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20040810130122.GA26326@elte.hu>; from mingo@elte.hu on Tue, Aug 10, 2004 at 03:01:22PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 10, 2004 at 03:01:22PM +0200, Ingo Molnar wrote: > > * William Lee Irwin III wrote: > > > On Tue, Aug 10, 2004 at 02:55:29PM +0200, Ingo Molnar wrote: > > > i'd guess it's the con->write() in __call_console_drivers() that makes > > > the difference. (i.e. touching the framebuffer) > > > > This is serial port IO; would that make the same kind of difference? > > serial port IO is even more heavy, it also generates IRQ traffic. Except serial console IO does not generate _any_ IRQ traffic - it purposely disables IRQs on the device before starting any IO to prevent any user-level IO interfering with the console output. It does, however, create a fair amount of IO reads and writes to the serial port. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core