From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932149AbWFUPFD (ORCPT ); Wed, 21 Jun 2006 11:05:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751639AbWFUPFD (ORCPT ); Wed, 21 Jun 2006 11:05:03 -0400 Received: from nf-out-0910.google.com ([64.233.182.185]:14711 "EHLO nf-out-0910.google.com") by vger.kernel.org with ESMTP id S1751635AbWFUPFA (ORCPT ); Wed, 21 Jun 2006 11:05:00 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=CID/gwKvJICejnniJ5TP0brC47Pak40IiLOqBImUjx3L8rqkHJJOhsqdS7hJ/ZGcp7gGWHvf+4AkKapl7Tsxx5G28U/IzeLoTMpmaJ5Y7DXcidbLAMztTyR+WZvd3uq44wu5jkuvk/oQKbLiFCSnuLX/FovF4kan5yPkzYb+8MU= Message-ID: <642640090606210804k282085efm84476af3a8fa08b1@mail.gmail.com> Date: Wed, 21 Jun 2006 09:04:58 -0600 From: "Ryan McAvoy" To: "Steven Rostedt" Subject: Re: realtime-preempt for MIPS - compile problem with rwsem Cc: LKML , linux-mips@vger.kernel.org, "Ingo Molnar" , "Thomas Gleixner" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <642640090606201208g31a0a57bm268910b026ccd335@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Steve, Thanks for your reply. Steven Rostedt wrote: > First, whenever sending mail about the -rt patch, always CC Ingo (and > perhaps Thomas Gliexner and myself). Thanks, I will do that. > 2.6.15 had lots of problems with -rt. Mainly the patch went through some > major rework, and Ingo was busy getting mutexes into mainline. So the > 2.6.15-rtX was sort of neglected. It would be best to use 2.6.16-rtX and > maybe even 2.6.17-rtX > > Which also comes the question: Which -rt patch are you actually trying? patch-2.6.15-rt21 . I have also tried using the 2.6.16 kernel and patch-2.6.16-rt29 and have the same problems with it. (I may be constrained in having to use a 2.6.15 kernel ... but would be happy to get 2.6.16 working /stable as a starting point.) > Yep, try the following patch: (completey untested since I don't have a > mips machine). > > config RWSEM_GENERIC_SPINLOCK > bool > - depends on !PREEMPT_RT > + depends on PREEMPT_RT > default y I did just that when I first started with these patches and did succeed in getting it compiling and booting. The resulting kernel, however, is very unstable and hangs frequently with no output. (It will hang within hours if left idle. I can hang it more quickly by attempting to use it). I have deadlock detection turned on and have confirmed that it does produce output at least for some deadlocks: http://groups.google.com/group/linux.kernel/browse_frm/thread/1559667001b7da2d/2558b539a5adc660?lnk=st&q=realtime+preempt+mips&rnum=2&hl=en#2558b539a5adc660 In the more common hangs though, I get no output. I decided to review the changes I made in getting it to compile and was hoping that this one may be the cause of the instability. I thought that perhaps this change was incorrect because include/asm-mips/rwsem.h is introduced by the rt-preempt patch and would only be used if RWSEM_GENERIC_SPINLOCK was off. [As well, it seemed like something fundamental enough to account for the general instability I am seeing.] Ryan