Programming Parallel Computers

HY 2023–2024

CP2a: instruction-level parallelism ★

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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:

Parallelize your solution to CP1 by exploiting instruction-level parallelism. Make sure that the performance-critical operations are pipelined efficiently. Do not use any other form of parallelism yet in this exercise. Please do all arithmetic with double-precision floating point numbers.

For this technical exercise, we have disabled auto-vectorization.

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 Operations Parameters
benchmarks/1 1,004,000,000 nx = 1000, ny = 1000
the input contains 1000 × 1000 pixels, and the output should contain 1000 × 1000 pixels
benchmarks/2 16,016,000,000 nx = 1000, ny = 4000
the input contains 4000 × 1000 pixels, and the output should contain 4000 × 4000 pixels

Here “operations” is our rough estimate of how many useful arithmetic operations you will at least need to perform in this benchmark, but of course this will depend on exactly what kind of an algorithm you are using.


In this task your submission will be graded using benchmarks/2: the input contains 4000 × 1000 pixels, and the output should contain 4000 × 4000 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
≤ 7.000 sec 1
≤ 6.000 sec 2
≤ 5.000 sec 3

For late submissions you will not get any points.