One byte per mutex sounds a bit suspicious given that atomic operations typically work on a word or cache line granularity. If you have two mutexes in the same

One byte per mutex sounds a bit suspicious given that atomic operations typically work on a word or cache line granularity. If you have two mutexes in the same cache line, false sharing occurs and the CPU interconnect gets busy. Locking two uncontended mutexes in same cache line on different cores ends up executing serially because the cores need to snoop each other's caches. Some benchmarks might be useful to see how this affects performance and CPU perf counters.