TU Wien:Effiziente Programme VU (Ertl)/Interview-questions

Please add the questions you remeber from the interview. Also maybe add how difficult you thought the interview was and how the process was.

Question?

   Answer 1 
   Answer 2 
   Answer 3

1. What are the limitations of Compilers?

- Limited Context (only looks at Code Blocks in Most cases; does not know what program actually is about) - Does not know how often each function, line, etc is called (except for Profile-guided Compilation; Therefore not 100% sure if this was actually a right answer) - actually a few more reasons but I cannot remember them right now

2. What is memory hierarchy and why is it important?

- Register(ALU) -> L1 -> L2 -> L3 -> RAM. Having to go deeper requires more cycles so we want to use top levels as much as possible. Spatial and temporal locality. Ways of improving latency/locality (linear access, ...).

3. What is the role of algorithms when it comes to efficiency?

- Optimizations do not make sense without a good algorithm. First make sure the optimal algorithm is being used. Do not get tricked by focusing only on big-O complexity -> sometimes due to locality more "complex" algorithms are more efficient (quicksort vs heapsort)