Dear students,
unfortunately, we discovered that we made a mistake in task 2 of the last assignment and, while asking you to find the performance for a difficult dependency chain of
a[i] += s * a[i-2];
, we did the grading and tutorial based on the much simpler loop kernel:
a[i] = s + a[i-2]; Therefore, the actual dependency stretches not only over the ADD but also the MULT and the correct performance estimation would have been \( \frac{2\,\textrm{it}}{14\,\textrm{cy}} = \frac{2}{7} \) flop/cy.
We apologize for this mistake on our side and we will redo the grading, keeping in mind that the task was much more difficult than originally planned, and update you here via Moodle when this is done.
We also updated the slides accordingly to match the actual task, so please download them again if you already did so before.
Finally, a shoutout and thanks to the student in yesterday's tutorial for pointing this out to us and helping us discover this error!