Not ignorant at all, You have actually pointed to the core of the problem. IMO It is not enough to know the logical constructs used for synchronization in para

Not ignorant at all, You have actually pointed to the core of the problem. IMO It is not enough to know the logical constructs used for synchronization in parallel programs, you have to know the hardware too. A little bit of everything from high-level parallel algorithms/data structures through memory consistency models, compiler optimizations to processor micro-architecture (cache coherency protocols, atomic instructions, NoC overhead etc.) is needed. Basically we need to be aware of the overheads for contention at every level in the system.