Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756830AbYBDTpB (ORCPT ); Mon, 4 Feb 2008 14:45:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754170AbYBDToy (ORCPT ); Mon, 4 Feb 2008 14:44:54 -0500 Received: from py-out-1112.google.com ([64.233.166.176]:4583 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753277AbYBDTox (ORCPT ); Mon, 4 Feb 2008 14:44:53 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; b=ZP3dvq9hAkcf4TLeOgs3NAtQX38V+W5vJv5dFhfRryGnNoIJ/9iJiW9GtDB4FDEHnWdiJ0qbwdRMwyGrY6uU5q68D/qby7s4PGcO3V2AZYVhZEkMVBtjaNNlsTKoucnLcJMannbFlEw+RNXpVLuX/C7ntJGBPiLbq6JwbywmGYQ= Message-ID: <3efb10970802041144j6b4e6893j293819238b5b82e8@mail.gmail.com> Date: Mon, 4 Feb 2008 20:44:51 +0100 From: "Remy Bohmer" To: "Haavard Skinnemoen" Subject: Re: [PATCH -mm v4 6/9] atmel_serial: Split the interrupt handler Cc: michael , fabio@gandalf.sssup.it, "Andrew Victor" , "Chip Coldwell" , "Marc Pignat" , "David Brownell" , linux-kernel@vger.kernel.org, "Alan Cox" In-Reply-To: <20080204133925.73733f5f@dhcp-252-066.norway.atmel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080129224316.GA23155@gandalf.sssup.it> <20080130104113.48ec376f@dhcp-252-066.norway.atmel.com> <47A051A7.7030004@gandalf.sssup.it> <20080130133659.55ebd828@dhcp-252-066.norway.atmel.com> <47A09723.7020000@gandalf.sssup.it> <20080130164631.7de4f6bd@dhcp-252-066.norway.atmel.com> <47A12A2E.5040309@gandalf.sssup.it> <20080131160721.6dddf30e@dhcp-252-066.norway.atmel.com> <3efb10970801311136y12670f12x6e4fdd44de3677b9@mail.gmail.com> <20080204133925.73733f5f@dhcp-252-066.norway.atmel.com> X-Google-Sender-Auth: 2783dbf42de6fd71 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1206 Lines: 28 Hello Haavard, > That's what I was thinking too. If this is indeed the cause, the > dev_err() added by the debug patch I posted should trigger and we may > consider boosting the priority of the tasklet (using > tasklet_hi_schedule.) Notice that we are talking about Preempt-RT here. Everything is running in thread context, even tasklets, softirqs etc. They are _all_ preemptible, and if Michael has some RT-thread in the system that has a higher priority than this tasklet or softirq, than the buffer will eventually overflow. I wonder also if Michael has set the RT-priorities correctly, on RT _every_ softirq/irq thread starts by default on priority 50, SCHED_FIFO. If they are still at 50, any other softirq/tasklet, or irq can make this behavior worse. Notice that the default 50 thingy rarely gives a decent behaving system. (But any other default will also give problems anyway, so it _has_ to be customized/tuned by the end user) Kind Regards, Remy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/