Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750934AbVKBD1A (ORCPT ); Tue, 1 Nov 2005 22:27:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750953AbVKBD1A (ORCPT ); Tue, 1 Nov 2005 22:27:00 -0500 Received: from wproxy.gmail.com ([64.233.184.194]:13135 "EHLO wproxy.gmail.com") by vger.kernel.org with ESMTP id S1750932AbVKBD07 convert rfc822-to-8bit (ORCPT ); Tue, 1 Nov 2005 22:26:59 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=jxphB3MdXiyb5hsSf0gUQyQCjxYZxwNS3P1ZjjwTM+FYTMKTyf1sXiav1oFCtHoglLY25F8PlqwEjXPkyUvdFmQxRVFiqPcch3BKgb7tuvli2qEjDslQDoyeMFwTZIkSNEZtOkSYciiMkl+o9I0Ryb/lSqvrRsREx5mMNHQ6zDk= Message-ID: Date: Tue, 1 Nov 2005 22:26:58 -0500 From: Carlos Antunes To: Steven Rostedt Subject: Re: 2.6.14-rt1 Cc: Fernando Lopez-Lezcano , Ingo Molnar , Rui Nuno Capela , "K.R. Foley" , Florian Schmidt , john stultz , Mark Knecht , Thomas Gleixner , linux-kernel@vger.kernel.org In-Reply-To: <1130900716.29788.22.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <20051017160536.GA2107@elte.hu> <20051020195432.GA21903@elte.hu> <20051030133316.GA11225@elte.hu> <1130876293.6178.6.camel@cmn3.stanford.edu> <1130899662.12101.2.camel@cmn3.stanford.edu> <1130900716.29788.22.camel@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1418 Lines: 36 On 11/1/05, Steven Rostedt wrote: > On Tue, 2005-11-01 at 21:55 -0500, Carlos Antunes wrote: > > > > > Fernando, > > > > I'm also having some when using SCHED_FIFO and SCHED_RR. When running > > several hundred threads, each sleeping on a loop for 20ms, SCHED_OTHER > > performs ok with latencies of less than 10ms while with SCHED_FIFO or > > SCHED_RR, I see latencies exceeding 1 full second! > > Are you saying that you have several hundred threads in SCHED_FIFO or > SCHED_RR? Or is just Jack as that. > It's a simple program I put together to test wakeup latency. Each thread basically sleeps for 20ms, wakes up and executes a couple of instructions and goes back to sleep for another 20ms. Multiply this by a thousand. What I found out is that, inthis situation, and using realtime-preempt, SCHED_OTHER offers 3 orders of magnitude less latency than SCHED_FIFO or SCHED_RR. Which suggests to me there is something fishy going on. Carlos -- "We hold [...] that all men are created equal; that they are endowed [...] with certain inalienable rights; that among these are life, liberty, and the pursuit of happiness" -- Thomas Jefferson - 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/