Scheduling on heterogeneous ARM SoC

Greg V greg at
Mon Feb 4 17:00:55 UTC 2019

On Sun, Feb 3, 2019 at 5:29 PM, John F Carr <jfc at> wrote:
> Some ARM-based single board computers combine two types of Cortex 
> processors, for example 4 A73 and 4 A 53 or 2 A72 and 4 A53.  How 
> does FreeBSD schedule processes on these chips?  Does it use all 
> cores at random, only the "big" or "little" set, or something more 
> complicated?

Pretty much "at random" i.e. doesn't take the differences between cores 
into account.

I'd really like to have a "fill up fastest cores first" mode, because 
for building software on my RK3399 board I've had to either not do 
anything and sometimes end up with big cores idling when little cores 
are compiling, or to cpuset to big cores which would end up not 
utilizing the little cores in highly parallel build phases…

More information about the freebsd-arm mailing list