When I run this script:
import torch

a = torch.rand(1000, 10000)
while True:
    print('.')
    a.tanh_()

and then open htop, I expect to see all 8 cores running at 100%, but only 4 seem to be running? :

Screen Shot 2017-07-17 at 9.01.08 AM.png1544×224 42.4 KB

Thoughts?
[edit: also, the 4 cores that are running are not exactly running at 100% either]