Programming Parallel Computers

HY 2023–2024

IS4: fast solution ★★

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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:

Using all resources that you have in the CPU, solve the task as fast as possible. You are encouraged to exploit instruction-level parallelism, multithreading, and vector instructions whenever possible, and also to optimize the memory access pattern. Please do all arithmetic with double-precision floating point numbers.

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.


Name Parameters
benchmarks/1 nx = 100, ny = 100
the input is a multicolor image with 100 × 100 pixels
benchmarks/2a nx = 199, ny = 199
the input is a multicolor image with 199 × 199 pixels
benchmarks/2b nx = 200, ny = 200
the input is a multicolor image with 200 × 200 pixels
benchmarks/2c nx = 201, ny = 201
the input is a multicolor image with 201 × 201 pixels
benchmarks/3 nx = 400, ny = 400
the input is a multicolor image with 400 × 400 pixels


In this task your submission will be graded using benchmarks/3: the input is a multicolor image with 400 × 400 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
≤ 10.000 sec 1
≤ 8.000 sec 2
≤ 4.000 sec 3
≤ 3.000 sec 4
≤ 2.000 sec 5

For late submissions you will not get any points.