gatherList() slow in parallel
 

Hi foamers,

I am writing code for a parallel simulation in which I use gatherList() and scatterList() to collect centres of cells that have an alpha value greater than 0.5 (max is 1).
Pstream::gatherList(gatheredidCellAlpha);
Pstream::scatterList(gatheredidCellAlpha);

I will then do some calculations using these cells (adding up their volumes, getting their velocityVectorField, finding all their neigbours).

I have written codes for both serial and parallel mode, and with gatherList()/scatterList() parallel mode is slower than the serial mode with the same mesh!

Can anyone provide solution to such a problem?

Best regards,
Carlen