Le 2012-02-14 à 11:14:00, Charles Henry a écrit :
On 2/13/12, Mathieu Bouchard matju@artengine.ca wrote:
Do you understand what I say, or you just repeat what I was replying to ?
I thought I understood--was there something I missed?
I wouldn't have known that from your reply. It seemed to just continue where you had left. When I want to just add more to something I said, I just reply to my own mail. I don't quote someone's mail to say something completely unrelated to the quote.
The point of the original remark is that you always lose some of your potential computing power when trying to use multiple resources.
Part of the computing power has to be put on communication and coordination, which are essential parts of collaboration. It doesn't necessarily mean that those ressources could have been used for anything else. If you measure a programme's computing time without counting its I/O, it'll appear more efficient than if you counted the I/O. For multi-processor computing involving divide-and-conquer or pipelining, some of the work internal to the algorithm is I/O and you can't avoid measuring it. This might skew perception a bit.
You contrast with the capability of parallel computing to accomplish a certain amount of work in less time. I don't want to argue with you--these are just the two sides of the coin.
Yes, I was stating the other side, because there hadn't been any clarifications on what « the sum » and « the parts » ought to be in that case. People compare total amounts of gigaflops because they can, and because it's fairly simple to measure a score to determine a winner, which leads to competitions that take a lot of time and effort. This orients a lot of the default thinking about what is « the » goal of parallelism.
I had actually typed out and then deleted some more things
I also do that a lot. If I had kept them, I could make a book out of them, and store it in a random position in the Library of Babel.
about a successful project that accelerated computing time from weeks to hours, but I thought they were boring.
If you want to post it, post it, and if you don't want to, don't.
______________________________________________________________________ | Mathieu BOUCHARD ----- téléphone : +1.514.383.3801 ----- Montréal, QC