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

OpenFOAM Multi-Core Solving across Physical vs. Logical Cores in Virtual Machine

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 28, 2016, 11:53
Question OpenFOAM Multi-Core Solving across Physical vs. Logical Cores in Virtual Machine
  #1
New Member
 
Vyssion's Avatar
 
Vyssion
Join Date: Mar 2016
Posts: 12
Rep Power: 10
Vyssion is on a distinguished road
So I have been looking for ways to optimise my CFD code to run faster and more stable, and have come across this conundrum that a mate of mine pointed out might not be the case...

According to a few sources, when solving across multiple cores, there is very little to no benefit in decomposing over more than the number of physical cores that you have in your machine; that is, hyper-threading offers no substantial benefit.

My issue with this is that for a native linux build, sure, make sense. But I am not running natively - but rather inside a Virtual Box VM...

So I am wondering whether the same applies to VM setups; especially since the Virtual Machine doesn't "see" the same thing that the native OS does and may not be able to see whether a core is physical or logical. I had assumed that VMs and Native builds functioned differently and at the moment, I run the VM across 6 cores reserving two for my native OS and then decompose OpenFOAM into 8 processor cores which solve. I need to change that come to think of it as I write this!!

But yeah, so should I decompose into a (2 2 1) or would there be some benefit to perhaps decompose into a (2 3 1) if the VM can't tell the difference between the physical and logical cores. Or leave it as (2 2 2).
__________________
Optimism, pessimism, f*ck that: We're going make it happen. As God is my bloody witness, I'm hell-bent on making it work.
- Elon Musk in 2008, after three unsuccessful Falcon launches.
Vyssion is offline   Reply With Quote

Old   September 28, 2016, 13:34
Default
  #2
Senior Member
 
Mahdi Hosseinali
Join Date: Apr 2009
Location: NB, Canada
Posts: 273
Rep Power: 18
anishtain4 is on a distinguished road
The best way to say is to have test runs same as the last post in the topic you mentioned.
anishtain4 is offline   Reply With Quote

Reply

Tags
core, decompose, multi, processor, virtual machine


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
chtMultiRegionSimpleFoam: maximum number of iterations excedeed. Nkl OpenFOAM Running, Solving & CFD 19 October 10, 2019 03:42
conjugate heat transfer in OpenFOAM skuznet OpenFOAM Running, Solving & CFD 99 March 16, 2017 06:07
Floating point exception error lpz_michele OpenFOAM Running, Solving & CFD 53 October 19, 2015 03:50
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 07:20
Micro Scale Pore, icoFoam gooya_kabir OpenFOAM Running, Solving & CFD 2 November 2, 2013 14:58


All times are GMT -4. The time now is 05:51.