A very bad experience of the interview. The interviewer had a set of questions, from which he was asking. He was more into definitions than concepts. The interviewer looked to be of very less experience. He had no idea how modern technologies, parallel programming or high performance works in modern day of computing. He looked only interested in getting the definitions of the questions from his list. The questions he asked was pretty much from undergrad data structure class. I would suggest to send a senior engineers if you are interviewing a senior engineers.

3 stages, 4 if you count the recruiting agency I was a part of. First, a semi technical interview with hard algorithmic questions, hard constraints (like only most optimal solution) also went through resume and talk about the position. Then, two devs with lots of questions about tech stack, not that hard but at the end two coding problems, also quite hard. Finally, a culture fit interview which seemed more of a formality than anything else.