Contact Model Optimization

LIGGGHTS 컴파일 단계에서 Contact Model 에 따른 Optimization이 가능한가 봄.

make auto 말고 다른 옵션을 알아보자.

WARNING: 
	The contact model you specified is not located in any whitelist.
	Because of this the model will be run in an unoptimized version (increasing runtime by up to 20%).
	In order to optimize this model you have the following options:
		(i)  Run the genAutoExamplesWhitelist.sh script in your LIGGGHTS(R) source folder to automatically parse the input script
		(ii) Add the model combination by hand to your style_contact_model_user.whitelist that can be found in your LIGGGHTS(R) source folder
		(iii) Use the ENABLE_MODEL_* flag when building with cmake.
	If you perform one of the steps above LIGGGHTS(R) needs to be recompiled to generate the optimized code.

 (../contact_models.h:365)

https://www.cfdem.com/media/DEM/docu/Section_start.html?highlight=whitelist 

2. Getting Started — LIGGGHTS v3.X documentation

 

All model combination of LIGGGHTS(R)-PUBLIC are automatically available starting with version 3.7. However, only a subset of them are compiled in an optimized manner. This might give you performance losses between 5 and 20%. In case you are using a model combination that is not optimized, LIGGGHTS(R)-PUBLIC will notify you of this. In this case you can create a file called style_contact_model_user.whitelist in your LIGGGHTS(R)-PUBLIC src/ folder and fill it with entries such as

 

EPSD2 Rolling Friction 모델을 쓰는 Hertz 모델을 추가해 보자. 아래의 파일에 추가한다.

style_contact_model_user.whitelist

GRAN_MODEL(HERTZ, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_EPSD2, SURFACE_DEFAULT)

여기서 좋은 답변을 찾은 듯

https://www.cfdem.com/forums/superquadrics-compilation

superquadrics compilation | CFDEM®project

LIGGGHTS uses a (from my point of view) complicated make system.

Some contact models are predefined to be compiled in a optimized fashion - and some others not to keep filesize small and compile time low.
What you should do is to open LIGGGHTS-PUBLIC/src/style_contact_model_user.whitelist and add at least:

GRAN_MODEL(HOOKE, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_OFF, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HERTZ, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_OFF, SURFACE_SUPERQUADRIC)

after that recompile liggghts with make clean all && make auto in your LIGGGHTS-PUBLIC/src/ folder.
When you plan to use SQ with rolling friction enabled add

GRAN_MODEL(HOOKE, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_CDT, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HERTZ, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_CDT, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HOOKE, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_EPSD, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HERTZ, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_EPSD, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HOOKE, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_EPSD2, SURFACE_SUPERQUADRIC)
GRAN_MODEL(HERTZ, TANGENTIAL_HISTORY, COHESION_OFF, ROLLING_EPSD2, SURFACE_SUPERQUADRIC)

too.
Have a look in style_contact_model.h to get all possible definitions.

When you want to compile all 3240 pissible contact model combinations change line 214 in Make.sh to 3240 and start compiling (this will take a long long time and results in a 150MB executable :-) )

Hope this helps,
Christian.

컴파일은

make clean all && make auto

 

== 추가 수정사항이 있음, 입력파일이 있으면, whitelist를 자동으로 만들어 주는 bash 스크립트가 /LIGGGHTS/src 디렉토리에 존재함

예를 들어 다음과 같이 사용함

$ ./genAutoExamplesWhitelist.sh
genAutoExamplesWhitelist.sh - searches paths recursively for LIGGGHTS example input scripts (in.*), and extracts the pair styles, version 0.1
usage: genAutoExamplesWhitelist.sh [-o outputfile] [-s LIGGGHTS src directory path] [-i] [-v] [-f] [-a] [paths|files]
    -o: output filename (default: ./style_contact_model_autoExamples.whitelist)
    -s: specify LIGGGHTS src directory path (default: ./)
    -i: do not search recursively, look in specified files
    -a: search recursive in all files, not only in.*
    -f: force outfile to be overwritten
    -v: verbose

Example:
    genAutoExamplesWhitelist.sh ../examples/LIGGGHTS

 

실제 사용해 보면, style_contact_model_autoExamples.whitelist 파일이 작성됨

$ ./genAutoExamplesWhitelist.sh ./in.Shibuya_SQ
parsing of input scripts completed
they are added to the whitelist: style_contact_model_autoExamples.whitelist , only "style_contact_model_autoExamples.whitelist" is automatically invoked

 

작성된 파일의 내용은 아래와 같음

GRAN_MODEL(HERTZ, TANGENTIAL_OFF, COHESION_OFF, ROLLING_OFF, SURFACE_DEFAULT)

 

그런데, 이상함. 내가 사용한 LIGGGHTS에서 pair style은 아래와 같이 SuperQuadrics를 사용하도록 되어있는데, Surface가 Default로 나옴

pair_style         gran model hertz surface superquadric            # Hertzian without cohesion

 

한가지 추가사항 : SuperQuadric은 컴파일시 다음의 옵션을 사용함

make auto USE_SUPERQUADRICS=ON

 

이러면, make.auto 파일에서 자동으로 SuperQuadrics 옵션으로 컴파일을 진행 함

 

=== 추가사항

genAutoExamplesWhitelist.sh 스크립트에 문제가 있으니, 수동으로 등록하라고 함.

그리고 gcc 버전 8 이상에서는 whitelist가 큰 의미가 없다고 하네.. 잉?

https://www.cfdem.com/forums/problems-self-created-contact-model