What are the benefits/main uses of message passing abstractions when the hardware is shared address?
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jon
I'll take a crack at this...
I believe there are cases in which the message passing paradigm is a more natural fit for expressing an algorithm (in particular, Distributed Algorithms - http://en.wikipedia.org/wiki/Distributed_algorithm).
For example, consider the "program" from the first day of class where each processor has a number, and we wanted to sum them all up. The standard shared-memory solution would be to have a global sum variable, and then have all of the processors lock the variable, add their element, and then unlock the variable. However, a message passing solution could easily express the 210 "reduce" algorithm or the "row-by-row" algorithm, which has a lower time complexity.
Here's an article which tries to answer, "Is message passing obsolete?" (it answers 'no') - http://www-users.cs.umn.edu/~kumar/papers/passing.ps. The main points the article makes are that message passing is useful because it enables programmers to account for access conflicts, to optimize data movement between processors, and to conceptualize parallel programmers in a different--and often more natural--way.
What are the benefits/main uses of message passing abstractions when the hardware is shared address?
This comment was marked helpful 0 times.
I'll take a crack at this...
I believe there are cases in which the message passing paradigm is a more natural fit for expressing an algorithm (in particular, Distributed Algorithms - http://en.wikipedia.org/wiki/Distributed_algorithm).
For example, consider the "program" from the first day of class where each processor has a number, and we wanted to sum them all up. The standard shared-memory solution would be to have a global sum variable, and then have all of the processors lock the variable, add their element, and then unlock the variable. However, a message passing solution could easily express the 210 "reduce" algorithm or the "row-by-row" algorithm, which has a lower time complexity.
Here's an article which tries to answer, "Is message passing obsolete?" (it answers 'no') - http://www-users.cs.umn.edu/~kumar/papers/passing.ps. The main points the article makes are that message passing is useful because it enables programmers to account for access conflicts, to optimize data movement between processors, and to conceptualize parallel programmers in a different--and often more natural--way.
This comment was marked helpful 0 times.