Programming Parallel Computers

HY 2023–2024

MF1: CPU baseline ★

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What you will need to do in this task

Please read the general instructions for this exercise first. Here are the additional instructions specific to this task:

Implement a simple sequential baseline solution. Make sure it works correctly. Do not try to use any form of parallelism yet. You are expected to use a naive algorithm that computes the median separately for each pixel, with a linear-time median-finding algorithm.

What I will try to do with your code

I will first run all kinds of tests to see that your code works correctly. You can try it out locally by running ./grading test, but please note that your code has to compile and work correctly not only on your own computer but also on our machines.

If all is fine, I will run the benchmarks. You can try it out on your own computer by running ./grading benchmark, but of course the precise running time on your own computer might be different from the performance on our grading hardware.

Benchmarks

Name Parameters
benchmarks/1 hx = 10, hy = 10, nx = 100, ny = 100
the input contains 100 × 100 pixels and the window dimensions are 21 × 21 pixels
benchmarks/2 hx = 10, hy = 10, nx = 500, ny = 500
the input contains 500 × 500 pixels and the window dimensions are 21 × 21 pixels
benchmarks/3 hx = 10, hy = 10, nx = 1000, ny = 1000
the input contains 1000 × 1000 pixels and the window dimensions are 21 × 21 pixels
benchmarks/4 hx = 10, hy = 10, nx = 1500, ny = 1500
the input contains 1500 × 1500 pixels and the window dimensions are 21 × 21 pixels

Grading

In this task your submission will be graded using benchmarks/4: the input contains 1500 × 1500 pixels and the window dimensions are 21 × 21 pixels.

The point thresholds are as follows. If you submit your solution no later than on Saturday, 31 August 2024, at 23:59:59 (Helsinki), your score will be:

Running timePoints
≤ 30.000 sec 1
≤ 20.000 sec 2
≤ 15.000 sec 3
≤ 12.000 sec 4
≤ 9.000 sec 5

For late submissions you will not get any points.