Improve value exchange infrastructure concurrent access

Although the new value exchange infrastructure (MB-25903 and MB-26489) have added 60% throughput to perfrunner's Q1, there's still work that can be done.

Currently producers and consumers access the value exchange infrastructure via a couple of locked structures, which makes value exchange serialised.

It would be good to have producers and consumers exchange values without having to stop (assuming that there are free cores where they can both run), which could be done with a lockless or quasi lockless infrastructure.