Python scikit learn n_jobs

Question

This is not a real issue, but I\'d like to understand:

• running sklearn from Anaconda distrib on a Win7 4 cores 8 GB system
• fitting a KMeans model on a 200

Answer 1

• what is the point of using n-jobs (and joblib) if the the library uses all cores anyway?

It does not, if you specify n_jobs to -1, it will use all cores. If it is set to 1 or 2, it will use one or two cores only (test done scikit-learn 0.20.3 under Linux).