Be careful of the implicit context

IOgrind has been released a while ago.  Its advantage over live system 
profiling is that the results are deterministic whereas live system 
performance measurements can (according to Meeks) differ as much as 10% 
(on Linux) from run to run.  On a properly designed system, you don't 
(anymore) find that large bottlenecks, they are smaller.

If the bottlenecks are larger, I would assume one could catch them even 
with strace (just strace all applicable processes at the same time).