CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Parallel Computing on Multi-Core Processors

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 5, 2007, 14:19
Default Parallel Computing on Multi-Core Processors
  #1
Upgrading Hardware
Guest
 
Posts: n/a
Hi Experts,

I see from some recent posts on here that multi-core processors are being used on CFX calculations now.

Could someone clarify how this works in words understandable by someone that knows a lot about CFD, but not as much about modern computer architecture and parallel computing?

Is this true parallel computing as would be done on many processors? Are PVM and MPI still both useable? If you have a cluster with 4 quadcore processors, do you really have 16 processors at work, or just 4 really quick processors? How does this work in terms of RAM allocation? One of the benefits of a 'standard' parallel job is that you can run bigger jobs as each processor has it's own RAM, is this advantage lost when using a quadcore? How about memory limitations due to the bus?

Anyway, these are probably really basic questions and I know that some of you guys on here have all the answers!

Don't all answer at once

  Reply With Quote

Old   June 5, 2007, 15:45
Default Re: Parallel Computing on Multi-Core Processors
  #2
Alex
Guest
 
Posts: n/a
Running CFX on multi-core processors works exactly as if each core were a separate processor. PVM and MPI still work, but there are distinctions to be made between local (i.e. all processors housed in same computer) and distributed (processors spread among multiple computers.) Each core still has it's own RAM, but this is of course limited by how much RAM is installed on each processor. You can still get the same benefit of increasing job size if you stack the multi-core processor with 2-4 Gb of RAM per core. As far as actual benefits and limitations due to the bus, see the posts from Joe and Stu from the past few days. The selling points for multi-core processing are vast, including that it allows for huge space, power, and cooling savings in cluster architecture.
  Reply With Quote

Old   June 5, 2007, 16:55
Default Re: Parallel Computing on Multi-Core Processors
  #3
Joe
Guest
 
Posts: n/a
Dual core Conroe-arch Intel (Desktop and Server) and AMD (Opeteron) cpus scale virtually linearly with all combinations of single socket (desktop), dual socket (intel server and amd server) and quad socket (amd server).

The only caveats are:

-Quad core intel chips (desktop and server) only allow you to utilise 3 of the 4 cores effectively. There are no quad core

-AMD server chips available now and probably wont be until late 2007.

Linking boxes via a simple gige interconnect gives virtually linear scaling for <24 cores in my experience.

  Reply With Quote

Old   June 5, 2007, 16:58
Default Re: Parallel Computing on Multi-Core Processors
  #4
Joe
Guest
 
Posts: n/a
Memory scaling is pretty linear too. If your problem took 4 GB to run on one core it will take 1 GB per core if you run on 4 etc.
  Reply With Quote

Old   June 5, 2007, 17:23
Default Re: Parallel Computing on Multi-Core Processors
  #5
Upgrading Hardware
Guest
 
Posts: n/a
Thanks guys ... I knew you would come up with the goods!
  Reply With Quote

Old   June 6, 2007, 18:58
Default Re: Parallel Computing on Multi-Core Processors
  #6
Frank
Guest
 
Posts: n/a
Could you give more information on communication protocols for HPC computing?

What do most people use? Ethernet, Gigabit ethernet, Myrinet, Infiniband ... something else?
  Reply With Quote

Old   June 7, 2007, 16:54
Default Re: Parallel Computing on Multi-Core Processors
  #7
Joe
Guest
 
Posts: n/a
Gige is perfectly fine for less than 32 cores.

If you account for the outrageous costs of exotic interconnects gige is still cheaper over 64 cores.
  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
solving a conduction problem in FLUENT using UDF Avin2407 Fluent UDF and Scheme Programming 1 March 13, 2015 03:02
Superlinear speedup in OpenFOAM 13 msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 06:36
Parallel computing quad core Prad Main CFD Forum 13 February 9, 2009 15:28
Find neighbours across processors in parallel computing xiao OpenFOAM Running, Solving & CFD 1 December 15, 2008 13:14
Parallel computing on dual core Fabio FLUENT 3 July 8, 2008 06:28


All times are GMT -4. The time now is 10:48.