The number of threads or cores to used running yade?

Asked by gaoxuesong on 2019-08-15

Hi, I have some questions about the cores and threads in parallel mode.

1. What's the difference between the --cores and -j ? In the documentation, they almost have the same defination.
    --cores Set number of OpenMP threads (as –threads) and in addition set affinity of threads to the cores given.
    -j Number of OpenMP threads to run

2. What can we get from the parameter of --performance?
     I have tried this parameter, it shows the time consuming of different engine parts for different number of particles. So it will help to improve the program?

3. In the section of Controlling parallel computation, there are to two ways to set the cores or threads for the job. One is the environmental variable OMP_NUMBER_THREADS, and the other is the -j X option. Also it says the cores number can be found in the /proc/cpuinfo. i have looked up this file, it has 8 processors and each has 1 cores. In fact, i set 8 cores to the ubuntu system in the VM. Does it mean my processors are single core processors?

4. How to set the right cores for a job?
    In the graphical controller created when yades stars, there is a item named iter. It shows the current iter and a velocity. Does this velocity is the calculation speed, iter per second? If so, is it feasible to try the number of cores used by this velocity?

Thanks,
Xuesong

Question information

Language:
English Edit question
Status:
Solved
For:
Yade Edit question
Assignee:
No assignee Edit question
Solved by:
gaoxuesong
Solved:
2019-08-19
Last query:
2019-08-19
Last reply:
2019-08-19
Robert Caulk (rcaulk) said : #1

>What's the difference between the --cores and -j ?

[1]

>So it will help to improve the program?

It tells you the current performance of your machine. It does not change the performance of your machine.

>Does it mean my processors are single core processors?

As opposed to?

>If so, is it feasible to try the number of cores used by this velocity?

Please reword this question, I do not understand what you are asking.

[1]https://answers.launchpad.net/yade/+question/218781

gaoxuesong (260582472-9) said : #2

Thank. The last question is that i want to know the meaning of some item on the graphical controller. As shown in the picture below,
https://drive.google.com/open?id=1fN9jBwQ1syuLJGPa7lqsk_mffidz6x6y
The iter #11514535, 45.0/s means the calculation speed is 45 iteration per second? What is the usual value?

Robert Caulk (rcaulk) said : #3

The simulation velocity depends on your computer hardware. There is no “usual” value

gaoxuesong (260582472-9) said : #4

So i think i will ask a new question about why my simulation speed is so low. I will supply a MSW example.