[LAU] Valgrind

Arnold Krille arnold at arnoldarts.de
Fri Nov 5 15:54:09 UTC 2010

On Friday 05 November 2010 13:53:56 Darrin Thompson wrote:
> Has anyone managed to get good results running valgrind vs. jackd or
> apps for it?
> My experience with Valgrind at work is you run it and it magically
> tells you the exact line of code where you have a serious bug, which
> is a good thing. But it has really high overhead. So I've been
> considering running it against say, Rosegarden, which I crashed
> repeatedly, but I'll beg off if someone has already been there and
> done that.

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,

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