RTEMS 4.11 runs slower as RTEMS 4.88 on a monoprocessor?

Thibaud Backenstrass thibaud.backenstrass at phelma.grenoble-inp.fr
Fri May 27 15:00:50 UTC 2016


I made a comparison of the timing performances of both RTEMS 4.8 and RTEMS
4.11 using the exact same application. Basically, the application creates
and starts a few tasks, then stops them almost immediately. It also
includes a timing observation service to know how much time each operation
Both RTEMS 4.8 and 4.11 are build with networking, POSIX API and Ada
support. The application is built the same way and executed under the TSIM
simulator for SPARC/LEON3, using only one processor.

I noticed that the execution of my application under RTEMS 4.11 is at least
10% slower than under RTEMS 4.8.0 and I am wondering:
- did the build options (and especially the optimization options) changed
between RTEMS 4.8 and RTEMS 4.11?
- is the gcc compiler 4.9.4 less “efficient” than the version 4.2.0 used to
build RTEMS 4.8.0?
- is RTEMS 4.11 slower due to the fact that is supports multiprocessor
(SMP) and that the structures (semaphores, ...) are more time consuming,
even on a monoprocessor?

Or what could be the reasons why RTEMS 4.11 runs slower than RTEMS 4.8 on a

Thanks in advance for your suggestions and ideas!

*Thibaud BACKENSTRASS* <thibaud.backenstrass at phelma.grenoble-inp.fr>
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