good load / stress suite?

[Matthieu Bec <mbec@gmto.org>]

Hello all,

I was wondering what people used to check RT_PREEMPT behavior under 
load/stress?

I'm trying to test the accuracy of my timers and have a test where I 
setup a kernel module with an hr-timer flipping RTS bit on serial COM0 
periodically, which I can look on an oscilloscope. the scope triggers on 
rising edge, I call jitter what shows on the falling side:
under no specific load I get ~ 10 us (worst case waiting a long time)


My initial idea for stressing the system was to compile a kernel, make 
-j 8 (#cores) that I thought would exercise CPU and IO if anything. As 
it happens, it's "mostly good" but I do get occasional (but repeatable) 
wild excursions (>100us)

Looking around, I found a tool called 'stress' - 
http://weather.ou.edu/~apw/projects/stress/
Under these new conditions, the system behaves really well again ~20 us 
stable all the way.

So both tests give different result, I'm not sure which to trust.
I was thinking maybe there is some weird interaction with the kernel and 
building the kernel that make the 'bad' test invalid?

I have RT_PREEMPT 3.0.18-rt34 SMP x86_64

Thanks,
-- 
Matthieu