CFD Online URL
[Sponsors]
Home > Forums > CD-adapco

Large Jobs and Memory

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 12, 2002, 15:22
Default Large Jobs and Memory
  #1
Peter Menegay
Guest
 
Posts: n/a
We do alot of large CFD runs at our site with Star-CD. We are considering upgrading our workstations to dual Xeon 2.4 GHz with 8 GB RAM. The 8 GB is available in server configurations. My question is, even if we have all that memory, will Star-CD be able to access it? OS will be Linux, presumably 32 bit. So far, with dual Xeon 1.7 GHz, I have never been able to access more than 2 GB.

Thanks,

Peter

  Reply With Quote

Old   August 13, 2002, 10:21
Default Re: Large Jobs and Memory
  #2
steve
Guest
 
Posts: n/a
I have seen prostar grab more than 3Gb on a Linux system with 4Gb of memory. The theoretical max is 4Gb (2^32) on any 32bit system (linux) that ignores the "-" sign or 2Gb (ie 2^31)on other systems that do not ignore it. It can't possibly assign more than 4GB to any one process. If you have 8GB it may be able to assign 4Gb to two processes at the same time (I don't really know).

The memory in STAR is laid out differently than prostar in that prostar gets it all from malloc, while STAR puts it in fixed fortran common blocks. I have seen this have an effect before on linux in particular and how much memory the programs can grab, so I can't be sure that STAR will grab more than 2GB (never really tried) even though prostar can.
  Reply With Quote

Old   September 4, 2002, 08:53
Default Re: Large Jobs and Memory
  #3
mikhail
Guest
 
Posts: n/a
I have succeeded in run of 4 GB StarCD 3.15 task with Intel850 chipset under RedHat7.1 os. More over, if your have prohpc your will be able access to all memory. (but it won't double run speed).
  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
Help with large sim stu CFX 7 June 4, 2007 18:13
Large solid Ernie FLUENT 0 July 12, 2006 03:41
large Reynolds Alf Main CFD Forum 4 September 22, 2005 11:20
Y* and really large .dat files Simon Blakey FLUENT 3 August 8, 2003 10:34
Large jobs and memory Peter Menegay CFX 2 August 23, 2002 06:39


All times are GMT -4. The time now is 13:21.