Monday, December 24, 2007

A comment on Rebecca's post

A useful teaching example for Parallel Processing courses is given in Rebecca's Blog: "Example Performance Evaluation"
I added the following comment:

"I liked the example and I think this kind of demonstrations really help explaining were bottlenecks may occur in the parallel code. I would like to add two comments:
1. Solving the matrix and obtaining 0 for the startup time, after already neglecting the bandwidth, means that the problem is totally Embarrassingly Parallel and this is indeed the case for MC calculations. It would be interesting to repeat the exercise for a communication intensive application, e.g. Laplace equation.
2. I think it worth mentioning Collective Communication commands, i.e. Bcast and Reduce in this context. In particular Reduce+Summation can be more efficient than the loop over the Recv because it can do summation out of order and this may hide some of the holding/communication time. Another alternative is to use MPI ANY_SOURCE in the Recv command.

--Guy"

Tuesday, December 18, 2007

Cloud Computing


I created a new group in Facebook about Cloud Computing.
You are all welcome to join!
Click here to visit the group web page:
http://www.facebook.com/group.php?gid=8450870046

Wednesday, December 12, 2007

TechnologyTrends: The next big thing must be Schnoodle

Google - The famous search engine and Internet related technologies
Doodle - Event scheduling
Moodle - A free open source course management system (CMS)
Schnoodle - A Schnoodle is a Poodle hybrid that is a cross-breed of a Poodle and a Schnauzer

Saturday, December 08, 2007

Do Google results make sense?

I did a Google digging research and became puzzled:
I searched for a few Buzz Words and then repeated the search with a combination of them.
The number of entries returned is not in accordance with the known laws of arithmetics!

"Grid Computing" 171,000 entries
where "XXX YYY" means with the exact phrase XXX YYY!
virtualization 1,530,000 entries
"Grid Computing" Virtualization 1,300,000 entries
where space between the terms means with all of the words.
virtualization -"grid computing" 2,580,000 entries
where "-" means exclude the term from the search
-virtualization "grid computing" 4,510,000 entries

In order to verify this mystery I repeated the test with two other terms:

Israel 26,600,000 entries
Jerusalem 4,190,000 entries
Jerusalem Israel 1,120,000 entries
jerusalem -israel 2,150,000 entries
-jerusalem israel 45,300,000 entries

To my understanding the situation can be demonstrated as in the following plot:




Does this mean we should make a compromise in East Jerusalem's territory
(have less Jerusalem and get more Israel) ???


Comments are welcome to shed light on this mystery

Note: If you want to reproduce my test take into account:
1. There may be a small change in the number of entries found. This fluctuation is however negligible.
2. There is another small difference in the number of entries if you try capital letters instead of small letters or change the order of the words.
3. Drawing was produced using the free tool Dia.