I spoke with a recruiter at a university career fair and received an OA (online assessment) a day later. The OA was a mix of coding and MCQ questions. I don't remember exact details, but the questions were not too tricky, and there was enough time. Basic multi-threading and parallelism knowledge was helpful.

I received a first-round interview invite on the day that I completed the OA. There were two 1-hour interviews: one focused on concurrency, and the other on algorithmic/data structures.

I received the final round invite one business day after that. The final round was a 1-hour interview, kind of object-oriented/design focused. There was also a half-hour "reverse" interview where I could ask the interviewer any questions about the company.

Overall, the turnaround times were very fast, and the interviewers and recruiters were helpful and knowledgeable. I got a very good impression of the intern program.

Also, don't be afraid of the concurrency interview.

Concurrency, Algorithmic, and Design questions.

The interview tested thought process and problem-solving rather than theoretical or memorized knowledge. I passed without having taken OS yet.