Regression on rt kernel while using POSIX timers

["Patel, Vedang" <vedang.patel@intel.com>]

Hi, 

I am trying to reproduce results in the Expected Results section on htt
ps://rt.wiki.kernel.org/index.php/Cyclictest

The results for the POSIX timers were not as I expected. The latency
for real-time kernel (v4.9.4-rt2) was worse compared to the mainline
kernel (v4.9.4). In almost all the cases, the latency is almost doubled
 with the max value reaching about 10 times when performing the tests
under load.

I was using a system with Intel® Atom processor C2758 and running the
following commands with no load and 100% load:
* cyclictest -t1 -p 80 -i 10000 -l 10000
* cyclictest -t1 -p 80 -i 500 -l 100000

I was using hackbench for generating the loads as follows:

./hackbench -p -s 100 -l 10000 -f 100 -P &

Does anyone have know of any known bugs which might be causing this
regression? 

Thanks,
Vedang Patel
Software Engineer
Intel Corporation