Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030467AbaDJPDs (ORCPT ); Thu, 10 Apr 2014 11:03:48 -0400 Received: from www.linutronix.de ([62.245.132.108]:47117 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934712AbaDJPDr (ORCPT ); Thu, 10 Apr 2014 11:03:47 -0400 Message-ID: <5346B2C8.6000207@linutronix.de> Date: Thu, 10 Apr 2014 17:03:36 +0200 From: Sebastian Andrzej Siewior User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.4.0 MIME-Version: 1.0 To: Clark Williams , Steven Rostedt CC: LKML , linux-rt-users , Mike Galbraith , "Paul E. McKenney" , Paul Gortmaker , Thomas Gleixner , Frederic Weisbecker , Peter Zijlstra , Ingo Molnar Subject: Re: [RFC PATCH RT] rwsem: The return of multi-reader PI rwsems References: <20140409151922.5fa5d999@gandalf.local.home> <20140410094430.56ca9ee1@sluggy.gateway.2wire.net> In-Reply-To: <20140410094430.56ca9ee1@sluggy.gateway.2wire.net> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/10/2014 04:44 PM, Clark Williams wrote: > The means of each group of five test runs are: > > vanilla.log: 1210117 rt.log: 17210953 (14.2 x slower than > vanilla) rt-fixes.log: 10062027 (8.3 x slower than vanilla) > rt-multi.log: 3179582 (2.x x slower than vanilla) > > > As expected, vanilla kicked RT's butt when hammering on the > mmap_sem. But somewhat unexpectedly, your fixups helped quite a > bit and the multi+fixups got RT back into being almost > respectable. > > Obviously these are just preliminary results on one piece of h/w > but it looks promising. Is it easy to look at the latency when you have multiple readers and and a high prio writer which has to boost all those readers away instead just one? Or is this something that should not happen for a high prio RT task because it has all memory already allocated? > > Clark Sebastian -- 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/