Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754995AbXJAUoS (ORCPT ); Mon, 1 Oct 2007 16:44:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752822AbXJAUoK (ORCPT ); Mon, 1 Oct 2007 16:44:10 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:42432 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752617AbXJAUoJ (ORCPT ); Mon, 1 Oct 2007 16:44:09 -0400 Subject: Re: [HACK] convert i_alloc_sem for direct_io.c craziness! From: Peter Zijlstra To: Zach Brown Cc: Steven Rostedt , LKML , linux-rt-users , mingo@goodmis.org, Thomas Gleixner In-Reply-To: <20071001195256.GB7718@mami.zabbo.net> References: <20071001195256.GB7718@mami.zabbo.net> Content-Type: text/plain Date: Mon, 01 Oct 2007 22:39:16 +0200 Message-Id: <1191271156.5574.9.camel@lappy> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 917 Lines: 23 On Mon, 2007-10-01 at 12:52 -0700, Zach Brown wrote: > Do you have any suggestions for locking constructs that RT would prefer? Basically, anything that maps to a simple mutex. Anything more complex gets real messy real quick. Locks that have non-exclusive states become non-deterministic because an unbounded number of contexts can be in this state. Hence acquisition of the exclusive state has unbounded time. Even when limited to a bounded number, the ramifications to the PI graph will get you a head-ache. Also, non-owner locks, ie. semaphores (asymetric acquisition vs release contexts) are unusable because the lack of ownership undermines PI - who to boost? - 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/