On Friday 05 November 2010 13:53:56 Darrin Thompson wrote: I did manage to run jackd (with the firewire backend) inside valgrind -- tool=callgrind. Its not suitable to get any audio output but it gives some numbers and showed me the main processing time is spent in the locks for phase-locked-loop of the streaming-clock... Might be biased because the streaming clocks of pc and device where running completely different because of the valgrind overhead. But experiments without valgrind and without the locks gave reason that really a lot of time is spent waiting there. Unfortunately the locks are needed as it will crash without them... But its possible and does give some numbers and hints. The overhead of the memcheck tool is lower then the overhead of callgrind btw. Have fun, Arnold