From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4F0C58B7.1080602@domain.hid> Date: Tue, 10 Jan 2012 10:26:47 -0500 From: Makarand Pradhan MIME-Version: 1.0 References: <4F0B530A.80905@domain.hid> <4F0C5524.9020501@domain.hid> In-Reply-To: <4F0C5524.9020501@domain.hid> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] Issue with Auto relax and nested mutexes List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Philippe Gerum Cc: "xenomai@xenomai.org" Hi Phillippe, You are right. Task 1 requires to be started with prio 0. I start seeing the problem after task2 grabs the mutex and releases them. The first task never jumps back to seconodary. Here is my output. The mode never goes back to 0 after "Grabbing mux in HP" and the rescnt stays stuck at 1 in the kernel. root@domain.hid:~# ./relax 0 1 Spawning: tasks bP: 0, cp: 0, mode: 0 Acquire complete Release complete bP: 0, cp: 0, mode: 0 Acquire complete Release complete bP: 0, cp: 0, mode: 0 Acquire complete Release complete bP: 0, cp: 0, mode: 0 Acquire complete Grabbing mux in HP Mux held by Task2 Release complete bP: 0, cp: 0, mode: 1 Acquire complete Release complete bP: 0, cp: 0, mode: 1 Acquire complete Rgds, Mak. On 10/01/12 10:11 AM, Philippe Gerum wrote: > On 01/09/2012 09:50 PM, Makarand Pradhan wrote: >> Hi, >> >> I am running kernel 3.0.0, xenomai: 2.6, powerpc 8360. >> >> I am noticing an issue while using the auto relax feature related to >> mutexes. I am using nested mutexes. The code is attached to this email. >> >> The problem is that I am not relaxing after a RT thread grabs and >> releases a mutex. On further investigation, it was noted that the rescnt >> is not going down to 0. > From your code, task1 would auto-relax only if started with priority 0, > which is what I get here: > > -bash-3.2# ./relax 0 1 > Spawning: tasks > bP: 0, cp: 0, mode: 0 > Acquire complete > Release complete > bP: 0, cp: 0, mode: 0 > Acquire complete > Release complete > bP: 0, cp: 0, mode: 0 > Acquire complete > Release complete > ... > > Conversely, I get the right behavior if setting a non-zero priority to > task1: > > -bash-3.2# ./relax 1 0 > Spawning: tasks > bP: 1, cp: 1, mode: 1 > Acquire complete > Release complete > bP: 1, cp: 1, mode: 1 > Acquire complete > Release complete > bP: 1, cp: 1, mode: 1 > Acquire complete > ... > > In any case, the priority of task2 should have no impact on the result. > > I'm running current 2.6 HEAD commit (168da46de), kernel 3.1.5/powerpc32 > (52xx), pipeline 2.13-06. > > Which priority arguments are you passing to your test program? > >> Another observation is that I do not hit >> rt_mutex_release in the kernel in the problem scenario, I believe when >> the thread undergoes a priority inversion.This may be a problem as the >> rescnt would not get decremented. Not sure how the mutex is releasing >> wiithout hitting rt_mutex_relase or am I missing anything? >> > These are fast mutexes, the thread does not have to jump to kernel space > unless the released mutex was actually contented. > >> If I have both the tasks running at priority 0, I stay in the secondary >> domain, rt_mutex_release is invoked as expected, the rescnt goes down to >> 0 when all the mutexes are released. >> >> Has anyone faced this problem? >> > I'm unsure there is any yet. Auto-relax applies to non -rt Xenomai > threads only (i.e. prio == 0). > >> Rgds, >> Makarand >> >> >> >> >> >> >> >> _______________________________________________ >> Xenomai-help mailing list >> Xenomai-help@domain.hid >> https://mail.gna.org/listinfo/xenomai-help > -- ___________________________________________________________________________ NOTICE OF CONFIDENTIALITY: This e-mail and any attachments may contain confidential and privileged information. If you are not the intended recipient, please notify the sender immediately by return e-mail and delete this e-mail and any copies. Any dissemination or use of this information by a person other than the intended recipient is unauthorized and may be illegal. _____________________________________________________________________