Introduction Name: Jani Peusaari Office: 6608 Contact: Reception hours: Wednesday 13-14

Timetable wk 1: Introduction, terms, other basic stuff wk 2: Complexity analysis wk 3: Abstract models wk 4: Abstract models, architectures wk 5: Interconnections, embedding wk 6: Communications wk 7: Practical issues, coding assignment

Exercises Not mandatory in general No extra points from attendance Internet: –Not all answers / explanations published in the web Course web page –Changes to schedule, questions, feedback

Terms Task – Tehtävä –General description of a processing element Process – Prosessi –A process runs in some arbitrary computer Thread – Säie –”Lightweight process”, threads run in some arbitrary process Communication –Between tasks, processes, threads

Terms Shared Memory – Jaettu muisti Distributed Memory – Hajautetty muisti Architecture –Way to connect Processors to each other Problem size: n, N Number of tasks: p, P Memory: m, M Time to complete certain operation: t, T

Example 1 The job is to estimate how long it takes to count n numbers with p people, One person calculates n numbers in (n-1)t c. Let us presume, that there are eight persons and the numbers are easily divided among them. Transferring the results takes t w. How long it takes for n people if: a) They are sitting in a circle b) They are sitting in 2 by 4 rows.

Example 2 One person uses (n-1)t c to count n numbers. Is it possible that p persons solves the problem in less time than (n-1)t c /p ? Justify your answer !

Example 3 What if the eight people from assignment number 1 calculate partial sums on the blackboard so that everyone can see the others results as soon as they are ready. How long a time it takes now and how about assignment number 2?