Alberto, Please add more practical-related info like if your cluster is homogenous, if the number of maps and reduces in both runs are consistent (i.e., same data and same amount of reducers on 4 vs. 7?), and if map speculatives are on. Also, do you notice difference of time for a single map task across the two runs? Or is the difference on the reduce task side?
On Tue, Jun 21, 2011 at 8:33 PM, Alberto Andreotti <[email protected]> wrote: > Hello, > > I'm working with an application to calculate the temperatures of a squared > board. I divide the board in a mesh, and represent the board as a list of > (key, value) pairs with a key being the linear position of a cell within the > mesh, and the value its temperature. > I distribute the data during the map and calculate the temperature for next > step in the reduce. You can see a more detailed explanation here, > > http://code.google.com/p/heat-transfer/source/browse/trunk/informe/Informe.pdf > > but the basic idea is the one I have just mentioned. > The funny thing is that the more nodes I add the slower it runs!. With 7 > nodes it takes 16 minutes, but with 4 nodes it takes only 8 minutes. > You can see the code in file HeatTransfer.java which is found here, > > http://code.google.com/p/heat-transfer/source/browse/#svn%2Ftrunk%2Ffine%253Fstate%253Dclosed > > thanks in advance! > > Alberto. > -- > José Pablo Alberto Andreotti. > Tel: 54 351 4730292 > Móvil: 54351156526363. > MSN: [email protected] > Skype: andreottialberto > -- Harsh J
