CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

slow down running in parallel

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 3, 2007, 18:41
Default slow down running in parallel
  #1
laf
Guest
 
Posts: n/a
I am running a problem with a sliding interface in parallel. On 2 processors it takes about twice as long to run as on a single processor. I have : turned off hyperthreading removed monitors reduced file outputs to a minimum streamlined the udf used for the motion

I tried adding in each component of the model, turbulence, sources, ideal gas, material properties and the moving mesh where the interfaces do not communicate.

The slow down occurs with the moving mesh and a sliding interface are activated.

I have tried partitioning along the interface, perpendicular to the interface, encapuslating, non encapsulated, segregated and coupled solvers.

FLUENT believes it is a communication slow down.

I have tried on windows and LINUX platforms without any change.

Are there any workarounds for this problem? Has any one overcome this problem?
  Reply With Quote

Old   April 4, 2007, 02:48
Default Re: slow down running in parallel
  #2
Karl
Guest
 
Posts: n/a
If you are using the sliding- or dynamic mesh - method the grid rotation for every timestep always takes place on the host computing node. Therefore you have large communication traffic between your computing nodes and this slows down your simulation.

The best speedup i have reached on a 4-cpu shared memory workstation was 2.4 to 2.6 for a simulation using sliding mesh . On our cluster the speedup was almost lower because we have only gigabit-ethernet connection between the nodes.
  Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
running OpenFoam in parallel vishwa OpenFOAM 20 November 7, 2012 15:33
Running mapFields with Parallel Source and Parallel Target RDanks OpenFOAM Mesh Utilities 2 June 6, 2011 07:56
Statically Compiling OpenFOAM Issues herzfeldd OpenFOAM Installation 21 January 6, 2009 09:38
Kubuntu uses dash breaks All scripts in tutorials platopus OpenFOAM Bugs 8 April 15, 2008 07:52
running multiple Fluent parallel jobs Michael Bo Hansen FLUENT 8 June 7, 2006 08:52


All times are GMT -4. The time now is 20:15.