Ciao Thomas,

this new version of the preempt-rt patch seems to be a good step forward 
with respect to a problem I have in a benchmark application I am running 
on top of a kernel v2.6.29.4 patched with it on a quad-core Intel(R) 
Xeon(R) machine. Within this benchmark I am making use of pthreads and 
semaphores and sometime it happens that a call to "sem_wait()" returns 
"-1" and sets the "errno" to "512" - which corresponds to "ERESTARTSYS" 
- which up to my poor kernel knowledge should never be delivered to the 
user space.
Now, with the new version of the preempt-rt patch, the frequency of 
these odd "sem_wait()" return values has notably diminished, though not 
completely stopped. So, I thought it might be interesting for you if I 
share a workaround with you which seems to eliminate the odd 
"sem_wait()" return values (as it did work already for preempt-rt patch 
version rt17). Note, that this for sure is not a bug fix, but just a 
workaround for which I am even not a 100% sure that it is semantically 
correct, but maybe it gives you a hint on what might still go wrong in 
the RT patch. Pls. find attach the "rcsdiff" output on file 
"kernel/futex.c" containing the workaround.

Best regards,
Wolfgang Betz