Re: [Xenomai] Mutex enhancement for Auto relaxed threads

[Makarand Pradhan <makarandpradhan@ruggedcom.com>]

>  Will quickly test this and get back.

Yes. That's pretty much how the system behaves.

Rgds,
Makarand.

Test program attached:
Results:
task1: Prio 0 Auto relaxed
task2: Prio 10. RT.
root@ruggedcom:~# ./tc5 0 10 1
Format: tc5 prio1 prio2 mux_iterations.
Spawning: task1
task2: Mutexes created
task2: Mutexes in memory
Running task1: status: b00380
task1: Global test: 25
task1: Acquiring mux1
rt_mutex_acquire_inner: Did system call. lockcnt: 1, dsof: 1
task1: Acquired mux1. rc: 0
task1: status: b00180
task1: Acquiring mux2
task1: Acquired mux2. rc: 0
task1: status: b00180
task1: Releasing mux1
rt_mutex_release: Doing system call. lockcnt: 0, dsof: 1
task1: Released mux1. rc: 0
task1: status: b00380 <- Relaxed task1 while holding mutex 2.
task1: bprio: 0 cprio: 0 status: b00380 info.status: b00380
task2: Acquiring mux2.
task1: bprio: 0 cprio: 10 status: b01180 info.status: b01180 <- task1 
jumps to primary again..
task1: Releasing mux2
rt_mutex_release: Doing system call. lockcnt: 0, dsof: 1
rt_mutex_acquire_inner: Did system call. lockcnt: 1, dsof: 1
task2: Acquired mux2.
task2: Releasing mux2
rt_mutex_release: Doing system call. lockcnt: 0, dsof: 1
task2: Released mux2. rc: 0
task2: status: 300180
task1: Released mux2. rc: 0
task1: status: b00380


On 22/11/12 11:47 AM, Makarand Pradhan wrote:
> Hi Gilles,
>
> lock mutex1
> lock mutex2
> unlock mutex1
> unlock mutex2
>
> As per my current implementation, I expect the thread to relax after
> unlocking mutex1. If another RT thread starts waiting on mutex2, I
> expect the thread holding the mutex will harden and start running in
> primary again. Will quickly test this and get back.
>
> I did consider this scenario but since we never use such a behaviour in
> our system, did not pursue it further.
>
> This brings up another question that I was contemplating. Do we want to
> harden unless there is another RT thread wanting this mutex? If not then
> the implementation becomes simpler and the scenario mentioned would also
> get addressed automatically.
>
> Rgds,
> Mak.
>
>
>> I did not look in details at your code, but what if I do
>>
>> lock mutex1
>> lock mutex2
>> unlock mutex1
>> unlock mutex2
>>
>> ?
>>
>


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