On 19/12/14 14:53, Hesham Moustafa wrote:
On Thu, Dec 18, 2014 at 4:38 PM, Joel Sherrill
<joel.sherr...@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.sherr...@oarcorp.com> wrote:
>>>
>>>On December 18, 2014 5:18:31 AM PST, Sebastian
Huber<sebastian.hu...@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.
Actually our MrsP implementation allows suspension (blocking in RTEMS
terms). In this case the idle thread executes using the scheduler node
of the thread so that the priority ceiling property is preserved (e.g.
no lower priority task can get the processor).
--
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.hu...@embedded-brains.de
PGP : Public key available on request.
Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
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