From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932486AbWFHCfS (ORCPT ); Wed, 7 Jun 2006 22:35:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932489AbWFHCfS (ORCPT ); Wed, 7 Jun 2006 22:35:18 -0400 Received: from nz-out-0102.google.com ([64.233.162.195]:58204 "EHLO nz-out-0102.google.com") by vger.kernel.org with ESMTP id S932486AbWFHCfQ (ORCPT ); Wed, 7 Jun 2006 22:35:16 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=U7lrD2GIQqo6j6fP1ITh7MrSAmBoR5Bq/InM0LST+JKuMhf2qod4nF9X/51Aot2XCH8gY9I//HskTW8clfPfNLj9bLN+P8cfttzgk5rDco2ubOr7p0wUGwLVPgOcjPUvqBMsZXN8A0cpsKbSodvST80s+jofCqRfviCJx0UQ3/A= Message-ID: <9e4733910606071935o5f42f581g6392d5a23897fb09@mail.gmail.com> Date: Wed, 7 Jun 2006 22:35:15 -0400 From: "Jon Smirl" To: "Mathieu Desnoyers" Subject: Re: Interrupts disabled for too long in printk Cc: linux-kernel@vger.kernel.org, ltt-dev@shafik.org In-Reply-To: <20060608023102.GA22022@Krystal> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20060603111934.GA14581@Krystal> <9e4733910606071837l4e81c975t8d531ed9810af60f@mail.gmail.com> <20060608023102.GA22022@Krystal> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 6/7/06, Mathieu Desnoyers wrote: > * Jon Smirl (jonsmirl@gmail.com) wrote: > > You can look at this problem from the other direction too. Why is it > > taking 15ms to get between the two points? If IRQs are off how is the > > serial driver getting interrupts to be able to display the message? It > > is probably worthwhile to take a look and see what the serial console > > driver is doing. > > Hi John, > > The serial port is configured at 38000 bauds. It can therefore transmit 4800 > bytes per seconds, for 72 characters in 15 ms. So the console driver would be > simply busy sending characters to the serial port during that interrupt > disabling period. Why can't the serial console driver record the message in a buffer at the point where it is being called with interrupts off, and then let the serial port slowly print it via interupts? It sounds to me like the serial port is being driven in polling mode. > > Mathieu > > OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj.gpg > Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 > -- Jon Smirl jonsmirl@gmail.com