In all 3 demos, we mainly talk about the communication cost during the exchange of results. I think there is another significant cost we didn't mention here, which is synchronization cost. In the demos, the communication cost is the time people talks to each other and propagate the result. However, we can see that the time people spent adding up two big number or waiting for others' result is also significant. In demo 2, everyone tries to tell others his own result which results in a situation like dead lock, where no one can proceed. And people waiting for the last result due to the imbalance of work is also a kind of synchronization problem.
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It is interesting that even the best method of communication and distribution, there are certain tasks that as humans we just can't do and thus speedup is not always possible. For example, as smaller numbers are added up to bigger ones, calculating large digit numbers caused difficulty for the students. Its interesting that in this case (just the adding task), it is easier for an individual to add numbers since they are adding one small number at a time, whereas the group needs to merge their parallel processes (add large digit numbers together).
In all 3 demos, we mainly talk about the communication cost during the exchange of results. I think there is another significant cost we didn't mention here, which is synchronization cost. In the demos, the communication cost is the time people talks to each other and propagate the result. However, we can see that the time people spent adding up two big number or waiting for others' result is also significant. In demo 2, everyone tries to tell others his own result which results in a situation like dead lock, where no one can proceed. And people waiting for the last result due to the imbalance of work is also a kind of synchronization problem.
It is interesting that even the best method of communication and distribution, there are certain tasks that as humans we just can't do and thus speedup is not always possible. For example, as smaller numbers are added up to bigger ones, calculating large digit numbers caused difficulty for the students. Its interesting that in this case (just the adding task), it is easier for an individual to add numbers since they are adding one small number at a time, whereas the group needs to merge their parallel processes (add large digit numbers together).