From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261472AbVFCBLC (ORCPT ); Thu, 2 Jun 2005 21:11:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261478AbVFCBLB (ORCPT ); Thu, 2 Jun 2005 21:11:01 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:26867 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id S261472AbVFCBK4 (ORCPT ); Thu, 2 Jun 2005 21:10:56 -0400 From: "Sven Dietrich" To: "'Bill Huey \(hui\)'" , "'john cooper'" Cc: "'Perez-Gonzalez, Inaky'" , , "'Esben Nielsen'" , "'Ingo Molnar'" , , Subject: RE: [PATCH] Abstracted Priority Inheritance for RT Date: Thu, 2 Jun 2005 18:10:18 -0700 Message-ID: <002501c567d9$04e9ea10$c800a8c0@mvista.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 In-Reply-To: <20050603005422.GA6904@nietzsche.lynx.com> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Importance: Normal Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > > On Thu, Jun 02, 2005 at 01:43:54AM -0400, john cooper wrote: > > That might have been me. The last time I looked at this > specifically, > > full transitive promotion was being done in the RT patch. However > > unlike your attempt at scaling the lock scope, the RT patch had one > > lock which coordinated all mutex dependency traversals > system wide. > > This lock must be speculatively acquired even before we ascertain > > transitive promotion is required. > > > > So it doesn't scale as well as it could in the case of > > large count SMP systems. The response was that of "get > > it to work first and then we'll get it to scale" which > > is reasonable. > > Just curious, what do you thinks about the rw-lock comments > from Esben in that a real rw-lock can't be deterministic ? > I think it can be deterministic if the number of readers is limited (to 1)