re: asymmetric smp

[matthew green <mrg%eterna.com.au@localhost>]

> However, it has a quirk that I don't think our scheduler will deal with.
> 
> It has 4 Cortex-A15 cores @ 1.4Ghz and 4 Cortex-A7 cores @ 1.2Ghz.  Even
> if the frequencies weren't different, the A15 cores at least twice as
> fast per cycle than the A7.  That asymmetry is going to cause havoc with 
> the scheduler.  In terms of power, the A7s use a lot less than the A15s

why do you think the scheduler will have a major problem?

it certainly can be improved for this situation, but i've
got an SS10 with mis-matched cpus (2x100mhz, 1x150mhz,
the latter with a bigger cache and thus significantly
faster than the other cpus) and it works pretty fine.

so - my guess is that some of the power and performance
issues will still need work, but the system will boot
and run normally without special work.


.mrg.