http://wccftech.com/a11-chipset-2-power-cores-4-efficient-cores/

Apple second SoC based on TSMC’s 10nm FinFET architecture is the A11 chipset that’s expected to power the upcoming iPhone family. Details of the chip reveals that the company intends to up the total number of cores, resulting in greater performance than what the A10 Fusion brought to the table.

A leaked tweet previously detailed that A11 was going to feature 4 performance cores, with the remaining two belonging to the efficient side of things. However, the leakster corrected his statement by revealing that two will be able to deliver groundbreaking performance for a smartphone, while the remaining four would tackle the less intensive operations.