Concurrent Fluent calculations in Linux

David Christopher · December 11, 2009, 19:59

I have 3 blades with 2 AMD chips each (each chip with 4 cores) all running Linux. How do I get concurrent instances of Fluent 6.3 (parallel version) to use different cores? When I start two instances of Fluent (say each using 4 cores) on the same machine, they use the same cores while the others remain inactive. Any suggestions? Thanks.

mystic_cfd · December 23, 2009, 16:14

Hi David,

I presume you are using version 6.3.26 where this was a known problem. If possible, request a post-release version from your supplier: the problem was fixed in version 6.3.33, and I have used 6.3.35 successfully as well.

In the meantime, there is a manual work around that was provided on the Online Technical Support site of Fluent (Solution 1440).

For example, after launching a 4-core run, type the following in the command window:
(set-affinity "0 4 1 5 2 6 3 7")
This will move the node processes 0,1,2,3 to the processor cores 4,5,6,7.
The strings contains a sequence of pairs of numbers, each pair consisting of a process id and a cpu/core id. Process ids are 0, 1, 2,... for the node processes, and the core IDs can be found in /proc/cpuinfo on Linux.

Hope this helps.

regards

December 11, 2009, 19:59	Concurrent Fluent calculations in Linux	#1
David Christopher New Member Dave Christopher Join Date: Dec 2009 Posts: 26 Rep Power: 17	I have 3 blades with 2 AMD chips each (each chip with 4 cores) all running Linux. How do I get concurrent instances of Fluent 6.3 (parallel version) to use different cores? When I start two instances of Fluent (say each using 4 cores) on the same machine, they use the same cores while the others remain inactive. Any suggestions? Thanks.

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December 23, 2009, 16:14		#2
mystic_cfd New Member HP Kritzinger Join Date: May 2009 Location: South Africa Posts: 25 Rep Power: 17	Hi David, I presume you are using version 6.3.26 where this was a known problem. If possible, request a post-release version from your supplier: the problem was fixed in version 6.3.33, and I have used 6.3.35 successfully as well. In the meantime, there is a manual work around that was provided on the Online Technical Support site of Fluent (Solution 1440). For example, after launching a 4-core run, type the following in the command window: (set-affinity "0 4 1 5 2 6 3 7") This will move the node processes 0,1,2,3 to the processor cores 4,5,6,7. The strings contains a sequence of pairs of numbers, each pair consisting of a process id and a cpu/core id. Process ids are 0, 1, 2,... for the node processes, and the core IDs can be found in /proc/cpuinfo on Linux. Hope this helps. regards