From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: [PATCH] Force processes to non-realtime before mm_exit Date: Wed, 25 May 2016 21:54:24 +0200 Message-ID: <574602F0.2070608@linutronix.de> References: <1462903464-11448-1-git-send-email-brian@peloton-tech.com> <20160512085946.GB19035@linutronix.de> <20160525163323.GB18036@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: rt-users To: Brian Silverman Return-path: Received: from www.linutronix.de ([62.245.132.108]:41726 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750840AbcEYTy1 (ORCPT ); Wed, 25 May 2016 15:54:27 -0400 In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 05/25/2016 08:00 PM, Brian Silverman wrote: >> Why can't the application drop the RT priority before its exit? Wouldn't >> that be appropriate? > > If it crashes or gets killed, it doesn't have a chance to drop priority. That is correct. The task with the highest priority is usually one of the most important ones. Usually if that task crashes or gets killed by the OOM killer while in production you have usually bigger problems than this. I'm neither pro nor against this patch. This patch can go actually upstream if accepted since it is not RT specific. If you have a good use case please submit please post it upstream and CC me. Once accepted I would pull it in -RT as well. > Yes, they are function traces without that patch applied. Every single > line in the file has a preempt count of at least 1. What I tried to figure out whether dropping RT prio alone solves the problem or if have additionally long preempt-disable regions. Based on your feedback you don't have long preempt-disable regions. > Brian Sebastian