Re: asymmetric smp

[Erik Fair <fair%netbsd.org@localhost>]

On Mar 27, 2014, at 11:29 , matthew green <mrg%eterna.com.au@localhost> wrote:

> 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.

I believe the point is to more nearly optimally schedule processes according to 
their needs on the processor(s) whose characteristics better match. Mr. Thomas 
also noted that this has energy use (power budget) implications.

Apple started a push in the "energy efficient software" direction last year at 
WWDC, clearly to prod third-party software developers into ligher impact on the 
energy budgets of both iOS mobile devices and MacOS X based laptops, but this 
sort of thing also has implications for HVAC and power bills in large scale 
data centers too. As I have been wont to say for a decade or two, "the hardware 
giveth and the software taketh away" and it would be a good thing for NetBSD's 
ongoing relevance if we paid some attention to efficiency of our software's 
algorithms and execution efficiency with the explicit goal of minimizing energy 
use of the computers our system runs on.

There are limits to what we can do; if users choose to run inefficient 
applications, or combine the software we provide in less-than-optimal ways with 
shell scripts, that's on them - we've (hopefully) done all we can do to provide 
them with the best tools.

        Erik <fair%netbsd.org@localhost>