Mutex obtain with timeout

[Hesham Moustafa]

On Thu, Dec 18, 2014 at 4:38 PM, Joel Sherrill
<joel.sherrill at oarcorp.com> wrote:
>
> On 12/18/2014 9:40 AM, Hesham Moustafa wrote:
>> On Thu, Dec 18, 2014 at 3:38 PM, Joel Sherrill
>> <joel.sherrill at oarcorp.com> wrote:
>>>
>>> On December 18, 2014 5:18:31 AM PST, Sebastian Huber <sebastian.huber at embedded-brains.de> wrote:
>>>> Hello,
>>>>
>>>> I work currently on concepts to implement mutex objects with SMP aware
>>>> locking protocols.  Currently this is MrsP [1] and OMIP [2]. The
>>>> implementation should use fine grained locking.  It turned out that the
>>>>
>>>> support for timeout makes the implementations much more complicated.
>>>> With timeouts you can tear a resource dependency tree into two
>>>> sub-trees
>>>> at arbitrary positions and this makes traversal difficult (you can cut
>>>> off the way back).
>>>>
>>>> Is there a valid use case for a mutex obtain operation with a timeout
>>>> in
>>>> case the locking protocol aims to provide bounded wait times?  We can
>>>> probably also assume that the critical section has a bounded execution
>>>> time.
I contacted Prof. Andy, and he said there is no MrsP use case with
time-out, because mutex lock/unlock operation does not allow
suspension in between.
>>> I don't know if there is or not. It is close to Christmas but I can try to email Burns and Wellings. I have met them both a few times and they gave usually been quick to answer.
>>>
>>> Or we could send Hesham to their office hours .. Lol
>>>
>> Before I read this, I was about to reply that I can contact them faster :)
>
> Please do and if you want to bring Sebastian and/or myself in, feel free to
> set up a Google Hangout.
>
> Say hi to them for me. :)
>>>> [1] A. Burns , A. J. Wellings, A Schedulability Compatible
>>>> Multiprocessor Resource Sharing Protocol -- MrsP, Proceedings of the
>>>> 2013 25th Euromicro Conference on Real-Time Systems, p.282-291, July
>>>> 09-12, 2013
>>>>
>>>> [2] Björn B. Brandenburg, A Fully Preemptive Multiprocessor Semaphore
>>>> Protocol for Latency-Sensitive Real-Time Applications, Proceedings of
>>>> the 2013 25th Euromicro Conference on Real-Time Systems, p.292-302,
>>>> July
>>>> 09-12, 2013
>>>>
>>>> --
>>>> Sebastian Huber, embedded brains GmbH
>>>>
>>>> Address : Dornierstr. 4, D-82178 Puchheim, Germany
>>>> Phone   : +49 89 189 47 41-16
>>>> Fax     : +49 89 189 47 41-09
>>>> E-Mail  : sebastian.huber at embedded-brains.de
>>>> PGP     : Public key available on request.
>>>>
>>>> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
>>>>
>>>> _______________________________________________
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>>> --joel
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>
> --
> Joel Sherrill, Ph.D.             Director of Research & Development
> joel.sherrill at OARcorp.com        On-Line Applications Research
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