CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

MPI slower than serial

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 24, 2015, 07:08
Default MPI slower than serial
  #1
New Member
 
Luca
Join Date: Jun 2015
Posts: 5
Rep Power: 10
LucaFen is on a distinguished road
Hi guys,
i'm trying to run my first parallel job on OpenFoam (but it's not my first time in parallel programming so i know the basic concepts).
I'm working on a duct so i'm pretty sure that the best choice to reduce communications between processors is to divide the duct in parts along the flow direction. Therefore in the decomposeParDict i choose the simple algorithm with (4 1 1) coefficients (i'm working on a quad-core computer).

The first problem is that the during the simulation one processor is faster than the others and waits for its neighbours only in the write times.

But the serious problem is that the serial simulation is faster than the parallel one.
I tried to run renumberMesh and got a little improvement but it's still slower than the serial.

I'm working with more than 600k cells.

Any guess about the reason why this happens?







I just missed a flag!! [SOLVED]

Last edited by LucaFen; November 24, 2015 at 10:45. Reason: I just missed a flag!! [SOLVED]
LucaFen is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
mpirun, best parameters pablodecastillo Hardware 18 November 10, 2016 13:36
parallel run is slower than serial run (pimpleFoam) !!! mechy OpenFOAM 18 August 17, 2016 18:19
Help: Serial code to parallel but even slower Zonexo Main CFD Forum 4 May 14, 2008 11:26
Error using LaunderGibsonRSTM on SGI ALTIX 4700 jaswi OpenFOAM 2 April 29, 2008 11:54
Is Testsuite on the way or not lakeat OpenFOAM Installation 6 April 28, 2008 12:12


All times are GMT -4. The time now is 04:01.