Hello,
I am glad that we had no RTEMS 4.11 release yet. I have to revisit the
RTEMS chain API.
This solution was a bad mistake as it runs out now:
http://git.rtems.org/rtems/commit/cpukit/sapi/include/rtems/chain.h?id=1215fd4d9426a59d568560e9a485628560363133
In order to support profiling of SMP locks and provide a future
compatible SMP locks API I have to add an SMP lock destroy function.
Since the patch adds an SMP lock to each chain control we would have to
add a rtems_chain_destroy() function as well. This is complicates the
chain usage dramatically. So I propose to revert the patch above. A
global SMP lock for all chains should be use to implement the protected
chain operations.
Advantages:
* The RTEMS chain API is now identical on SMP and non-SMP configurations.
* The size of the chain control is reduced and is then equal to the
Score chains.
* The protected chain operations work correctly on SMP.
Disadvantage:
* Applications using many different chains and the protected operations
may notice lock contention.
I think the chain control size drop is a huge benefit (RTEMS chain
controls are 66% larger than the Score chain controls). The only
disadvantage is not really a problem since these applications can use
specific interrupt locks and unprotected chain operations to avoid this
issue.
--
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.
_______________________________________________
rtems-devel mailing list
rtems-devel@rtems.org
http://www.rtems.org/mailman/listinfo/rtems-devel
