From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262517AbVFJI3h (ORCPT ); Fri, 10 Jun 2005 04:29:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262519AbVFJI3g (ORCPT ); Fri, 10 Jun 2005 04:29:36 -0400 Received: from 213-239-205-147.clients.your-server.de ([213.239.205.147]:30378 "EHLO mail.tglx.de") by vger.kernel.org with ESMTP id S262517AbVFJI3e (ORCPT ); Fri, 10 Jun 2005 04:29:34 -0400 Subject: Re: RT and timers From: Thomas Gleixner Reply-To: tglx@linutronix.de To: george@mvista.com Cc: Daniel Walker , linux-kernel@vger.kernel.org In-Reply-To: <42A8EE8C.1010406@mvista.com> References: <42A8EE8C.1010406@mvista.com> Content-Type: text/plain Organization: linutronix Date: Fri, 10 Jun 2005 10:30:31 +0200 Message-Id: <1118392231.13312.53.camel@tglx.tec.linutronix.de> Mime-Version: 1.0 X-Mailer: Evolution 2.2.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2005-06-09 at 18:36 -0700, George Anzinger wrote: > > I'm mainly concerned because that loop never breaks . It seems like there > > could be a condition when the loop never stops. For instance , a very > > accurate timer interrupt, and timers that continually reset themselves. > > As I recall, it is not possible to put a timer in the list for the current time. > It will be put in the next tick slot or, with HRT, be passed to the hrt code. > The only case this might fail is if a kernel hrt user restarts his timer for > "now" or prior to "now". This is bad and hard to correct. The posix-timers > code does not restart timers until the signal is delivered and then from the > user thread, not the softirq context. > > Did I miss something here? No, you're right. Expired timers are inserted into the next slot, so the loop is not able to starve itself. tglx