Inefficient SpinLock implementation

[anton-malakhov]

Describe the bug SpinLock as it is implemented in Quantum kills neighbor HyperThread performance and consumes excessive power.

Proposal Use PAUSE instruction (_mm_pause(); intrinsic) for short-duration lock. Use a back-off algorithm to gradually reduce bus traffic used for the atomic checks. Insert co-op yield point if it takes too long to acquire the lock.

Additional context

• The subject refers to this code: https://github.com/bloomberg/quantum/blob/master/quantum/impl/quantum_spinlock_impl.h#L33
• Please refer to this blog: https://software.intel.com/en-us/articles/long-duration-spin-wait-loops-on-hyper-threading-technology-enabled-intel-processors and Intel Optimization Manual

[accelerated]

Hi @anton-malakhov, yes the current implementation is rather simplistic. Given enough time I will look into this. However would you like to propose a PR instead? I notice boost has a cross-platform implementation which could potentially be used.