From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4F0C85E2.1070109@domain.hid> Date: Tue, 10 Jan 2012 13:39:30 -0500 From: Makarand Pradhan MIME-Version: 1.0 References: <4F0B530A.80905@domain.hid> <4F0C5524.9020501@domain.hid> <4F0C58B7.1080602@domain.hid> <4F0C5C00.3060508@domain.hid> <4F0C5C02.50308@domain.hid> <4F0C5C63.40105@domain.hid> <4F0C5E85.5080004@domain.hid> <4F0C7EAE.8080209@domain.hid> In-Reply-To: <4F0C7EAE.8080209@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 Phillipe, A bit surprised to see a change in sched-rt.h. I had another problem earlier where the XNOTHER was not getting set after a priority change. I had to look at the code that you have modified. Although I had temporarily worked around it by setting the XNOTHER in rt_task_set_priority. I think this would fix that problem as well. Will test the patch and get back with the results. Thanks and Rgds, Mak. On 10/01/12 01:08 PM, Philippe Gerum wrote: > On 01/10/2012 04:51 PM, Makarand Pradhan wrote: >> Based on my testing, it is noted that the rescnt is not released when >> task1 gets a priority boost and starts running with priority 1. That's >> when the rescnt is not decremented. >> >> It would imply that we may be checking the current priority while >> testing if we want to invoke rt_mutex_release in kernel. Will try to >> check it out. > Does this help in your case? > > diff --git a/include/nucleus/sched-rt.h b/include/nucleus/sched-rt.h > index cc1cefa..6ac8fd7 100644 > --- a/include/nucleus/sched-rt.h > +++ b/include/nucleus/sched-rt.h > @@ -87,7 +87,7 @@ static inline void __xnsched_rt_setparam(struct xnthread *thread, > { > thread->cprio = p->rt.prio; > if (xnthread_test_state(thread, XNSHADOW)) { > - if (thread->cprio) > + if (thread->bprio || !xnthread_test_state(thread, XNBOOST)) > xnthread_clear_state(thread, XNOTHER); > else > xnthread_set_state(thread, XNOTHER); >> Rgds, >> Mak. >> >> On 10/01/12 10:42 AM, Philippe Gerum wrote: >>> On 01/10/2012 04:40 PM, Philippe Gerum wrote: >>>> On 01/10/2012 04:40 PM, Makarand Pradhan wrote: >>>>> Another point: >>>>> >>>>> "These are fast mutexes, the thread does not have to jump to kernel >>>>> space >>>>> unless the released mutex was actually contented." >>>>> >>>>> When the first task is started with prio 0, I always see that >>>>> rt_mutex_release is invoked in the kernel. even when there is no >>>>> contention. >>>> I should have added: "unless there is no contention ... or the caller is >>>> a non-rt thread". This is because we have to jump to kernel space to >>>> track rescnt. >>>> >>> Ok, next try: "unless the mutex was contented ... or the caller is >>> a non-rt thread". >>> >>>>> I have an instrumented kernel. The kernel trace is given below. In this >>>>> trace only task1 is running at prio 0. It should be easy to follow: >>>>> >>>>> Jan 10 10:36:59 ruggedcom kernel: lo: rescnt: 0, switched: 0 >>>>> Jan 10 10:36:59 ruggedcom kernel: hi: rescnt: 0, switched: 0 >>>>> Jan 10 10:36:59 ruggedcom kernel: lo: rescnt: 1, switched: 1 >>>>> Jan 10 10:36:59 ruggedcom kernel: hi: rescnt: 2, switched: 0 >>>>> Jan 10 10:36:59 ruggedcom kernel: hi: rescnt: 3, switched: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: hi: rescnt: 3, switched: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: __rt_mutex_release >>>>> Jan 10 10:37:01 ruggedcom kernel: RML >>>>> Jan 10 10:37:01 ruggedcom kernel: rt_mutex_release: lockcnt: 1 >>>>> Jan 10 10:37:01 ruggedcom kernel: xnsynch_release_thread: BP: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: hi: rescnt: 2, switched: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: __rt_mutex_release >>>>> Jan 10 10:37:01 ruggedcom kernel: RML >>>>> Jan 10 10:37:01 ruggedcom kernel: rt_mutex_release: lockcnt: 1 >>>>> Jan 10 10:37:01 ruggedcom kernel: xnsynch_release_thread: BP: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: hi: rescnt: 1, switched: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: __rt_mutex_release >>>>> Jan 10 10:37:01 ruggedcom kernel: RML >>>>> Jan 10 10:37:01 ruggedcom kernel: rt_mutex_release: lockcnt: 1 >>>>> Jan 10 10:37:01 ruggedcom kernel: xnsynch_release_thread: BP: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: hi: rescnt: 0, switched: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: lo: rescnt: 1, switched: 1 >>>>> Jan 10 10:37:01 ruggedcom kernel: hi: rescnt: 2, switched: 0 >>>>> Jan 10 10:37:01 ruggedcom kernel: hi: rescnt: 3, switched: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: hi: rescnt: 3, switched: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: __rt_mutex_release >>>>> Jan 10 10:37:03 ruggedcom kernel: RML >>>>> Jan 10 10:37:03 ruggedcom kernel: rt_mutex_release: lockcnt: 1 >>>>> Jan 10 10:37:03 ruggedcom kernel: xnsynch_release_thread: BP: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: hi: rescnt: 2, switched: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: __rt_mutex_release >>>>> Jan 10 10:37:03 ruggedcom kernel: RML >>>>> Jan 10 10:37:03 ruggedcom kernel: rt_mutex_release: lockcnt: 1 >>>>> Jan 10 10:37:03 ruggedcom kernel: xnsynch_release_thread: BP: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: hi: rescnt: 1, switched: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: __rt_mutex_release >>>>> Jan 10 10:37:03 ruggedcom kernel: RML >>>>> Jan 10 10:37:03 ruggedcom kernel: rt_mutex_release: lockcnt: 1 >>>>> Jan 10 10:37:03 ruggedcom kernel: xnsynch_release_thread: BP: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: hi: rescnt: 0, switched: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: lo: rescnt: 1, switched: 1 >>>>> Jan 10 10:37:03 ruggedcom kernel: hi: rescnt: 2, switched: 0 >>>>> Jan 10 10:37:03 ruggedcom kernel: hi: rescnt: 3, switched: 0 >>>>> Jan 10 10:37:04 ruggedcom kernel: hi: rescnt: 3, switched: 0 >>>>> >>>>> >>>>> root@domain.hid:~# ./a.out 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 >>>>> ^C >>>>> >>>>> >>>>> Rgds, >>>>> Mak. >>>>> >>>>> >>>>> >>>>> On 10/01/12 10:26 AM, Makarand Pradhan wrote: >>>>>> 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. _____________________________________________________________________