Programming Parallel Computers

Aalto 2023

IS6b: fast GPU solution for 1-bit images ★★

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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:

Port your solution to IS6a to the GPU; again, make it run as fast as possible.

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 nx = 100, ny = 100
the input is a structured black-and-white image with 100 × 100 pixels
benchmarks/2a nx = 199, ny = 199
the input is a structured black-and-white image with 199 × 199 pixels
benchmarks/2b nx = 200, ny = 200
the input is a structured black-and-white image with 200 × 200 pixels
benchmarks/2c nx = 201, ny = 201
the input is a structured black-and-white image with 201 × 201 pixels
benchmarks/3 nx = 400, ny = 400
the input is a structured black-and-white image with 400 × 400 pixels
benchmarks/4 nx = 600, ny = 600
the input is a black-and-white image with 600 × 600 pixels

Grading

In this task your submission will be graded using benchmarks/4: the input is a black-and-white image with 600 × 600 pixels.

The point thresholds are as follows. If you submit your solution no later than on Sunday, 04 June 2023, at 23:59:59 (Helsinki), your score will be:

Running timePoints
≤ 8.000 sec 1
≤ 5.000 sec 2
≤ 3.000 sec 3
≤ 2.000 sec 4
≤ 1.000 sec 5

If you submit your solution after the deadline, but before the course ends on Sunday, 04 June 2023, at 23:59:59 (Helsinki), your score will be:

Running timePoints
≤ 5.000 sec 1
≤ 3.000 sec 2
≤ 1.000 sec 3

Contest

Your submissions to this task will also automatically take part in the contest, and you can receive up to 2 additional points if your code is among the fastest solutions this year!

Running timeExtra points
≤ 1.20 × fastest 1
≤ 1.05 × fastest 2