Fluent is so slow (CPU consumption problem)

hussainalshaikh · August 7, 2020, 05:56

I am using fluent to simulate and analyse a flow past a cylinder. My computer has 8 cores and 16 logical processors. When open fluent, I always run in parallel with 8 solver processes. However, the simulation run very slow and I don't get the speed I am expecting. The task manager always shows that 5-6% of the CPU consumed by cx2010 while each of the 7 fl_mpi2010 consume 6-7% of the CPU. I have another 2 cores laptop which shows that 25% is consumed by the cx2010 while only 2 fl_mpi2010 files consume 10% each. Whats going wrong here and how can I increase the speed of my runs?

karachun · August 7, 2020, 14:45

Turn off Hyper-threading and use only real cores. Fluent like many other CFD codes don't like Hyper-threading.

UPD

BTW 100/16 = 6.25 % - Task manager shows percent of total CPU load. One full loaded core is 6.3% of whole CPU. If you check the total load you see 55% value which corresponds to 8 of 16 cores fluent plus some load for Windows.

hussainalshaikh · August 7, 2020, 15:38

Thanks karachun,

How can I turn off hyper-threading?

karachun · August 7, 2020, 17:41

From BIOS, check your motherboard documentation.

August 7, 2020, 14:45		#2
karachun Senior Member Join Date: Nov 2015 Posts: 246 Rep Power: 11	Turn off Hyper-threading and use only real cores. Fluent like many other CFD codes don't like Hyper-threading. UPD BTW 100/16 = 6.25 % - Task manager shows percent of total CPU load. One full loaded core is 6.3% of whole CPU. If you check the total load you see 55% value which corresponds to 8 of 16 cores fluent plus some load for Windows. Last edited by karachun; August 7, 2020 at 17:41.

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August 7, 2020, 15:38		#3
hussainalshaikh New Member Join Date: Aug 2020 Posts: 2 Rep Power: 0	Thanks karachun, How can I turn off hyper-threading?

August 7, 2020, 17:41		#4
karachun Senior Member Join Date: Nov 2015 Posts: 246 Rep Power: 11	From BIOS, check your motherboard documentation.