What are GBT features?

hello,I am a very beginner to tvm, and I am confused about the features using in the cost model.
I am now reading the code of tune_nnvm_cuda.py in tutorials,and notice it use xgboost as cost model,feature_type is the default ‘itervar’.

But then I have problems following the code and don’t know what the features are exactly.

PS: I have read the paper Learning to Optimize Tensor Programs, Section4 Context Relation Features for GBT, whether the features are those described in paer?

Python interface:

C++ implementation and comments on the format:


Context relation features are called “CurveSampleFeature” in the code

Test (Examples):

Thanks a lot, I will check them.