Ask HN: Resources for low level (OS, concurrency, C++ trivia) content?

I'm a new grad trying to prep for HFT interviews. I noticed that some companies will ask these low level questions, and almost everything I read says something along the lines of "Oh, there's some C++ tricks you _just run into when you're working_." So HN, do you know any resources that can help me review concepts that show up in interviews?