lock contention - what can we do about it?

[David Nolden]

If the CPU time is below 100%, then that's for sure not due to lock
contention, but simply due to I/O. Either repeat the test with the
disk-cache better filled, or increase the number of threads.

QMutex will never be able to compete with inline spin-locks, because
it always requires at least full function-call for locking and
unlocking, whereas in the ideal case a spin-lock would only require to
increase and decrease a counter.

Beside that, I don't have time this weekend to take a deeper look into this.

Greetings, David