Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759053AbZAHTpn (ORCPT ); Thu, 8 Jan 2009 14:45:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752282AbZAHTpd (ORCPT ); Thu, 8 Jan 2009 14:45:33 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:44863 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751763AbZAHTpc (ORCPT ); Thu, 8 Jan 2009 14:45:32 -0500 Date: Thu, 8 Jan 2009 14:45:29 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Chris Mason cc: Linus Torvalds , Peter Zijlstra , Ingo Molnar , paulmck@linux.vnet.ibm.com, Gregory Haskins , Matthew Wilcox , Andi Kleen , Andrew Morton , Linux Kernel Mailing List , linux-fsdevel , linux-btrfs , Thomas Gleixner , Nick Piggin , Peter Morreale , Sven Dietrich Subject: Re: [PATCH -v7][RFC]: mutex: implement adaptive spinning In-Reply-To: <1231442273.14304.49.camel@think.oraclecorp.com> Message-ID: References: <1231347442.11687.344.camel@twins> <1231365115.11687.361.camel@twins> <1231366716.11687.377.camel@twins> <1231408718.11687.400.camel@twins> <20090108141808.GC11629@elte.hu> <1231426014.11687.456.camel@twins> <1231434515.14304.27.camel@think.oraclecorp.com> <1231442273.14304.49.camel@think.oraclecorp.com> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 897 Lines: 29 On Thu, 8 Jan 2009, Chris Mason wrote: > On Thu, 2009-01-08 at 13:14 -0500, Steven Rostedt wrote: > > > > If it was the current process that preempted the owner and these are RT > > tasks pinned to the same CPU and the owner is of lower priority than the > > spinner, we have a deadlock! > > > > Hmm, I do not think the need_sched here will even fix that :-/ > > RT tasks could go directly to sleeping. The spinner would see them on > the list and break out. True, we could do: if (owner) { if (!spin_on_owner(lock, owner)) break; } else if (rt_task(current)) break; That would at least solve the issue in the short term. -- Steve -- 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/