Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030203AbVJEQHz (ORCPT ); Wed, 5 Oct 2005 12:07:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030205AbVJEQHz (ORCPT ); Wed, 5 Oct 2005 12:07:55 -0400 Received: from 213-239-205-147.clients.your-server.de ([213.239.205.147]:11923 "EHLO mail.tglx.de") by vger.kernel.org with ESMTP id S1030203AbVJEQHy (ORCPT ); Wed, 5 Oct 2005 12:07:54 -0400 Subject: Re: 2.6.14-rc3-rt2 From: Thomas Gleixner Reply-To: tglx@linutronix.de To: david singleton Cc: Ingo Molnar , Steven Rostedt , linux-kernel@vger.kernel.org, john stultz In-Reply-To: References: <20051004084405.GA24296@elte.hu> <1128527319.13057.139.camel@tglx.tec.linutronix.de> Content-Type: text/plain Organization: linutronix Date: Wed, 05 Oct 2005 18:08:58 +0200 Message-Id: <1128528538.13057.145.camel@tglx.tec.linutronix.de> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1444 Lines: 36 On Wed, 2005-10-05 at 08:58 -0700, david singleton wrote: > > > > Yes. Thats happening. I moved the priority of softirq-timer above > > hackbench priority and the problem goes away. I look into this further. > > I had to set the threaded softirqs to real time priorities with the hi > thread at 24, > the timer thread at 23, net_rx at 22, etc. I wanted their priorities > just below the IRQ threads. > > The problem was the timer thread. Other real time threads got in its > way and held off timers. > > And I had to make a note if any higher priority apps depended on timers > that the timer > thread had to be boosted in priority to match that real time threads > priority. It's like > the softirqd's timer thread needs priority inheritance. Well, we had implemented this in one of the previous -rt versions for the high resolution timers. It was a bit hacky and I did not come around to reimplement it on top of ktimers. This is only a problem for itimers and posix interval timers at the moment. The nanosleep variants do not suffer from this problem as the wakeup happens directly from the hr timer interrupt. That way we have only one instead of two task switches. tglx - 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/