[OE-core] linux-yocto task performance numbers

[Richard Purdie]

Also, for reference/interest, the recent kernel populate_sysroot changes
took the kernel build time from over 11 mins to 8 mins. With the move to
3.19:

fedora19,master:5db6a27f4847e51c6434a968f81d3ceffcc54952 7:58.74
fedora19,master:5db6a27f4847e51c6434a968f81d3ceffcc54952 7:57.59
fedora19,master:5db6a27f4847e51c6434a968f81d3ceffcc54952 7:59.18
fedora19,master:5db6a27f4847e51c6434a968f81d3ceffcc54952 8:00.81
fedora19,master:5db6a27f4847e51c6434a968f81d3ceffcc54952 8:01.44
fedora19,master:5db6a27f4847e51c6434a968f81d3ceffcc54952 7:59.12
fedora19,master:172606338757d0b788e3382bf413102647307e1d 8:29.71
fedora19,master:172606338757d0b788e3382bf413102647307e1d 8:37.66
fedora19,master:172606338757d0b788e3382bf413102647307e1d 8:36.41
fedora19,master:172606338757d0b788e3382bf413102647307e1d 8:34.24
fedora19,master:172606338757d0b788e3382bf413102647307e1d 8:36.19

You can see 3.19 takes around 30-35s longer to build. These numbers are
extracted from our benchmark machine which monitors things like this.

Cheers,

Richard