Spinlocks

This repository contains a collection of spinlock implementations with various optimizations. This includes a basic (naive) spinlock, and ones with the following optimizations:

• Spinning locally
  • Addresses constant contention from writes
• Spinning with active backoff (for loop)
  • Addresses bursty contention when the lock is released
• Spinning with passive backoff (_mm_pause() intrinsic)
  • Addresses bursty contention with the lock is released and saves on power
• Spinning with exponential backoff
  • Addresses bursty contention and power while accounting for non-uniform wait times of threads
• Spinning with randomized backoff
  • Addresses bursty contention and power while accounting for non-uniform wait times of threads
• Ticket-based spinlock
  • Addresses unfairness from previous implementations

The benchmark used to evaluate the performance (among other metrics) of our spinlock is a simple loop where each thread increments a shared variable after grabbing the lock. This provides an extreme high-contention (but simple) scenario where we can evaluate out lock.

We also have benchmarks for the pthread_mutex_t, and pthread_spinlock_t, to compare performance and assembly against state-of-the-art locking mechanisms.