Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030206AbVJEQNh (ORCPT ); Wed, 5 Oct 2005 12:13:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030209AbVJEQNh (ORCPT ); Wed, 5 Oct 2005 12:13:37 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:59123 "EHLO hermes.mvista.com") by vger.kernel.org with ESMTP id S1030206AbVJEQNg (ORCPT ); Wed, 5 Oct 2005 12:13:36 -0400 In-Reply-To: <1128528538.13057.145.camel@tglx.tec.linutronix.de> References: <20051004084405.GA24296@elte.hu> <1128527319.13057.139.camel@tglx.tec.linutronix.de> <1128528538.13057.145.camel@tglx.tec.linutronix.de> Mime-Version: 1.0 (Apple Message framework v619) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: Content-Transfer-Encoding: 7bit Cc: john stultz , Ingo Molnar , linux-kernel@vger.kernel.org, Steven Rostedt From: david singleton Subject: Re: 2.6.14-rc3-rt2 Date: Wed, 5 Oct 2005 09:13:35 -0700 To: tglx@linutronix.de X-Mailer: Apple Mail (2.619) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1978 Lines: 59 On Oct 5, 2005, at 9:08 AM, Thomas Gleixner wrote: > 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. When I finally got the IRQ threads priorities straight and the softirqd priorities matched to be right underneath the IRQ priorities the system would run any benchmark I could throw at it with no problems, modulo the strange app that wanted to run at priority 99 and depended on itimers or sigarlm . . . For that case I had to match the softirq timer thread to that of the app before it would run with no problems. David > > 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/