RPI4 clock speeds and serial port ( temperatures idle and -j4 buildworld buildkernel )

[bob prohaska]

On Sat, Mar 20, 2021 at 10:41:48AM -0700, Mark Millard wrote:
> On 2021-Mar-20, at 08:56, bob prohaska <fbsd atwww.zefox.net> wrote:
> 
> > The most recent test on the 8GB Pi4 finished in 9 hours. That was after
> > running make cleandir twice, but having the installed system and the
> > sources relatively close (days) in age, on -current.
> 
> So a debug kernel was running? (Non-debug running for my builds.)

Yes.

> 
> Did it include a buildkernel? Or just a buildworld?
>

Just buildworld in 9 hours. 

> At around 9 hours, it would take standardizing on a (equivalent
> of) src.conf too be able to well compare your context vs. mine
> now, if we ever want to do so. I'll list my file later below
> for reference, although I'm probably more likely to try your
> src.conf content in my overclocked context than you are
> likely to try building via my src.conf like content in your
> powerd context.
>

No /etc/src.conf for this test, nor /etc/make.conf. 

> Welcome to the world of overnight (sleep-time) buildworld on a
> small board computer.
> 

It's a most welcome change!


> > That's with powerd
> > enabled, but no other speedup tweaks. Temps were just under  60 C, with
> > a fan in the case but no heatsinks on the ICs. 
> 
> Ambient temperature? (It is the difference that indicates how
> well your cooling is working and it is the difference that
> is more comparable across contexts. For example, my around
> 15.5C ambient likely was likely around 10C lower than for
> many reported figures.)
> 

Ambient was around 15-17 C at the times of observation. 

> >> sysctl dev.cpu.0.freq will definitely show the current freq.
> > 
> > On a Pi3 with GENERIC-MMCCAM kernel  (also running buildworld) it reports
> > bob at www:/usr/freebsd-src % sysctl dev.cpu.0.freq
> > dev.cpu.0.freq: 1200
> > also with no other speedup efforts beyond powerd. That machine has heastinks
> > on the ICs but only a fan blowing in through the openings in the plastic case.
> > It's around 60C. 
> > 
> > So far the effects of powerd seems to be uniformly good, with 
> > no downsides. Next, to try a Pi2 v1.1 (armv7)
> > 

The Pi2 V1.1 is now running buildworld with powerd enabled. Heatsinks
on the ICs, but no fan at all, < 50 C (17C ambient) with 0% idle, 900 
MHz, serial console seems to work fine. 

> 
> FYI (not that you are likely to build and run such:
>
[snipped for brevity]

Alas, you are right. It's already difficult to keep the 
experiments straight in my head......too many variations.

But, unless something most unexpected goes wrong, it seems
that powerd is useful on the Pi series computers.  

Thanks for writing!

bob prohaska