> No you haven't, you keep talking about doing something 100 times
That has not been part of all my explanations. But just so I can make it as clear as possible I will now explain it again without mentioning how many times it's called anywhere in the rest of my comment:
> if you have a lock between processes, getting those processes to wake up and know the unlock happened with low latency is what matters
Whether it matters depends on what you're benchmarking.
When the alternative to IPC is waking up another thread, your latency should be about the same either way. It's not what they were trying to compare.
The core comparison they wanted to make was about the simplicity of using a single lock type versus the overhead of using an IPC-capable lock everywhere. A better way to phrase their actual question is about how deep those IPC needs go in contrast to their downsides, not just whether there's a single call site somewhere.
> I replied to someone saying "how often do you use a shared lock in games" and I said there are obvious uses.
You gave a perfectly good answer to the half a sentence you quoted, if that half sentence was in a vacuum. But it was not in a vacuum, and your answer was not good for what they were actually asking.