How to increase core usage/performance?

cons013 · October 28, 2021, 05:46

Hi all, I am totally new to fluent and am running through Cornell uni's beginner free course. During the videos, the presenter runs some simulations that take mere seconds on his computer for thousands of iterations. While I am only using an i7 7700hq cpu (gtx 1060 too if it matters), my pc took quite a few minutes just to do one iteration! I feel that something is wrong here, but I don't know how to change anything.

On the fluent launcher I selected double precision as the presenter said to, and can't figure out where to change other options. My cpu is quad core with 8 threads and I have no idea how to tell if fluent is taking the full use of my cpu.

Any ideas? Thanks!

Edit: On a whim I tried setting 'number of processes' to 3 and it seems to do the trick. For a quad-core laptop, is it safe to put 4?

LoGaL · October 28, 2021, 07:17

Ye you can put 4, because most probably your processor has hyperthreadening. Infact, you can check it in the windows devicd manager, you should see 8 processors even though there are only 4 physical ones. Check the temperatures while running though

cons013 · October 28, 2021, 07:22

Thankyou!!

AlexanderZ · October 29, 2021, 01:12

as far as I know it is recommended to run fluent with number of nodes equal or less to number of physical cores you have (4 in your case). some times you may reserve 1 core for other programs.

its not possible to have such a big difference in performance, which you've mentioned. There must be a difference in cases.
running case on 4 cores instead of 1 will almost never increase computational speed 4 times.

cons013 · October 29, 2021, 01:27

I don't really know what was wrong. Fluent was being weird in general. First there was the painfully slow performance, then fluent itself wouldn't close when I clicked exit, I don't know. It seems to be working fine now.

arnie333 · November 6, 2021, 02:54

Open up Windows Task Manager and observe how the CPU, Memory (RAM) and HDD parameters behave when Fluent is running. I don’t think Fluent solver need to access your GTX 1060 graphics for the computational process, unless you tick the option at startup, but I suspect that it’s not possible with a 1060 card.

It could be a number of things. Perhaps not enough RAM and needs to constantly write to a slow HDD.

October 28, 2021, 05:46	How to increase core usage/performance?	#1
cons013 Member Join Date: Aug 2021 Posts: 63 Rep Power: 5	Hi all, I am totally new to fluent and am running through Cornell uni's beginner free course. During the videos, the presenter runs some simulations that take mere seconds on his computer for thousands of iterations. While I am only using an i7 7700hq cpu (gtx 1060 too if it matters), my pc took quite a few minutes just to do one iteration! I feel that something is wrong here, but I don't know how to change anything. On the fluent launcher I selected double precision as the presenter said to, and can't figure out where to change other options. My cpu is quad core with 8 threads and I have no idea how to tell if fluent is taking the full use of my cpu. Any ideas? Thanks! Edit: On a whim I tried setting 'number of processes' to 3 and it seems to do the trick. For a quad-core laptop, is it safe to put 4? Last edited by cons013; October 28, 2021 at 05:52. Reason: figured it out sort of

October 29, 2021, 01:12		#4
AlexanderZ Senior Member Alexander Join Date: Apr 2013 Posts: 2,363 Rep Power: 34	as far as I know it is recommended to run fluent with number of nodes equal or less to number of physical cores you have (4 in your case). some times you may reserve 1 core for other programs. its not possible to have such a big difference in performance, which you've mentioned. There must be a difference in cases. running case on 4 cores instead of 1 will almost never increase computational speed 4 times. __________________ best regards ****************************** press LIKE if this message was helpful

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
mpirun, best parameters	pablodecastillo	Hardware	18	November 10, 2016 13:36
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
Single Core vs. Multi Core Issue	Traction	FLUENT	2	May 14, 2014 14:52

October 28, 2021, 07:17		#2
LoGaL Senior Member Lorenzo Galieti Join Date: Mar 2018 Posts: 375 Rep Power: 12	Ye you can put 4, because most probably your processor has hyperthreadening. Infact, you can check it in the windows devicd manager, you should see 8 processors even though there are only 4 physical ones. Check the temperatures while running though

October 28, 2021, 07:22		#3
cons013 Member Join Date: Aug 2021 Posts: 63 Rep Power: 5	Thankyou!!

October 29, 2021, 01:27		#5
cons013 Member Join Date: Aug 2021 Posts: 63 Rep Power: 5	I don't really know what was wrong. Fluent was being weird in general. First there was the painfully slow performance, then fluent itself wouldn't close when I clicked exit, I don't know. It seems to be working fine now.

November 6, 2021, 02:54		#6
arnie333 New Member Arnie Join Date: Mar 2017 Posts: 27 Rep Power: 9	Open up Windows Task Manager and observe how the CPU, Memory (RAM) and HDD parameters behave when Fluent is running. I don’t think Fluent solver need to access your GTX 1060 graphics for the computational process, unless you tick the option at startup, but I suspect that it’s not possible with a 1060 card. It could be a number of things. Perhaps not enough RAM and needs to constantly write to a slow HDD.