Summary: due to the fact that each two­process entry and exit sec­
tion of Peterson's algorithm requires fewer remote op­
erations outside of busy­waiting loops than does ours.
This gives rise to the following open question: how many
remote operations outside of busy­waiting loops are re­
quired in two­process read/write algorithms based on
local spinning?
We end the paper with a few observations concerning
the time complexity of concurrent algorithms. A natu­
ral approach to measuring the time complexity of such
an algorithm would be to simply count the number of
operations. However, a straightforward application of
such an approach does not provide any insight into the
behavior of mutual exclusion algorithms under heavy
contention. In particular, in any algorithm in which pro­
cesses busy­wait, the number of operations needed for
one process to get to its critical section is unbounded.
In order to serve as a measure of time complexity, a
measure should be both intuitive and easy to compute.
In sequential programming, the usual measure of time

Source: Anderson, James - Department of Computer Science, University of North Carolina at Chapel Hill

Collections: Computer Technologies and Information Sciences