Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262629AbVCKKPr (ORCPT ); Fri, 11 Mar 2005 05:15:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262659AbVCKKPr (ORCPT ); Fri, 11 Mar 2005 05:15:47 -0500 Received: from cpe-24-94-57-164.stny.res.rr.com ([24.94.57.164]:21926 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S262629AbVCKKPk (ORCPT ); Fri, 11 Mar 2005 05:15:40 -0500 Date: Fri, 11 Mar 2005 05:15:39 -0500 (EST) From: Steven Rostedt X-X-Sender: rostedt@localhost.localdomain Reply-To: rostedt@goodmis.org To: Ingo Molnar cc: Lee Revell , linux-kernel@vger.kernel.org Subject: Re: [patch] Real-Time Preemption, -RT-2.6.11-rc3-V0.7.38-01 In-Reply-To: <20050311095747.GA21820@elte.hu> Message-ID: References: <20050204100347.GA13186@elte.hu> <1108789704.8411.9.camel@krustophenia.net> <20050311095747.GA21820@elte.hu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1620 Lines: 39 On Fri, 11 Mar 2005, Ingo Molnar wrote: > > * Steven Rostedt wrote: > > > > The short term fix is probably to put back the preempt_disables, the long > > > term is to get rid of these stupid bit_spin_lock busy loops. > > > > Doing a quick search on the kernel, it looks like only kjournald uses > > the bit_spin_locks. I'll start converting them to spinlocks. The use > > seems to be more of a hack, since it is using bits in the state field > > for locking, and these bits aren't used for anything else. > > yeah. bit-spinlocks are really a hack. > > Ingo > And this really sucks too! I've been looking into a fix for this and have yet to get something stable. As you probably already know, you can't just put back the preempt_disable since your spinlocks now schedule. So I've been looking into finding a way to get rid of these. I've tried making two global spinlocks, one for the state bit and one for the journal head bit use. But this deadlocks with j_state_lock. The journal head lock seems to be ok to be global, but the state lock needs to have one for every buffer head. I'm now hacking away to do this without touching the actual buffer head. But I'm not sure what some of the side effects this is having. I'll keep you posted when I get something working. I'm now having a crash course in how kjournal and friends work. -- 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/