The dominant term in the type of scenario you're describing is contention, not mutexes. I forget how big they're making Zen3 EPYCs right now, I think you can ge

The dominant term in the type of scenario you're describing is contention, not mutexes. I forget how big they're making Zen3 EPYCs right now, I think you can get like 64-128 physical cores. I can walk all over 128 different mutexes on each of those 128 cores for less than the cost of an L3 hit on that same EPYC box [1]. If I fuck up the affinity and they're all banging on one data structure? Yeah, it can jam the whole machine. This is why people who write good logging libraries are always playing games with buffering in thread-local storage and stuff. And sometimes you do need a bunch of producer threads dumping into a queue that simply can't be striped by anything (it's somewhat rare but it happens): in which case you want `folly::MPMCQueue` (or whatever Intel TBB calls their version of that) which Nathan Bronson was kind enough to get right so that other people don't have to end up with something both slow and wrong. A truly novel lock-free data structure that advances the SOTA in production software is a masters thesis, not a blog post. [1] This is a bit dated but it's good enough for eyeball work: https://gist.github.com/jboner/2841832 https://gist.github.com/jboner/2841832.