Date: Fri, 19 Mar 2021 17:53:02 -0700 From: bob prohaska <fbsd@www.zefox.net> To: Mark Millard <marklmi@yahoo.com> Cc: Klaus K??chemann <maciphone2@googlemail.com>, freebsd-arm <freebsd-arm@freebsd.org>, Diane Bruce <db@db.net>, bob prohaska <fbsd@www.zefox.net> Subject: Re: RPI4 clock speeds and serial port ( temperatures idle and -j4 buildworld buildkernel ) Message-ID: <20210320005302.GA40542@www.zefox.net> In-Reply-To: <FDBC2E89-8473-4C3A-B12E-78821949FDDB@yahoo.com> References: <20210318170053.GA26688@www.zefox.net> <9FFA0A51-C0B7-4121-95CA-B98669809007@yahoo.com> <E4CF6642-CB70-4495-A865-05469953561C@yahoo.com> <EA6BE351-98F5-4446-BA4D-948F04EDFD3B@yahoo.com> <81AC0353-258C-41C3-86B1-C133E33D97E3@yahoo.com> <20210319174359.GA38899@www.zefox.net> <FA5A110A-4E7A-4381-BBE5-9B3022CA9008@googlemail.com> <20210319195019.GA39087@www.zefox.net> <FDBC2E89-8473-4C3A-B12E-78821949FDDB@yahoo.com>
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On Fri, Mar 19, 2021 at 01:52:35PM -0700, Mark Millard wrote: > On 2021-Mar-19, at 12:50, bob prohaska <fbsd@www.zefox.net> wrote: > > > On Fri, Mar 19, 2021 at 08:07:36PM +0100, Klaus K??chemann wrote: > >> > >> > >>> Am 19.03.2021 um 18:43 schrieb bob prohaska <fbsd@www.zefox.net>: > >>> > >>> > >>> So my figures (~17 hours) seem reasonable for a default clocking. > >>> I thought maybe I'd done something wrong. > >> > >> > >> 17 hours sounds too long, you can simply enable ???powerd??? in rc.conf for automatically > >> scaling from idle 600 to max. 1500 (non overclocked). > >> So, when you hit make -j4 xyz, you will see all cpus running @~100% and > >> Powerd will then automatically set the clock speed to 1500 on all 4. > >> > > > > I've enabled powerd and rebooted, console messages report that powerd > > started with no explicit errors. A -j4 buildworld is running now. > > > > Should I expect to see powerd mess up the default mini-uart serial console? > > So far, it hasn't with top reporting less than 1% idle. That's confusing.... > > Avoid confusing the arm_freq with the core_freq (core is > VPU, not arm). The two are independent (up to the RPi* > firmware's dynamic frequency clocking logic anyway). > [sigh] Easier said than done, I'm choking on the alphabet soup... 8-) Is VPU the same as GPU? > I've already reported that the documentation indicates > that the core_freq is not supposed to be changed on the > RPi4's. (The use or not of 2 features controls the exact > value that it must be and the firmware appearently > already deals with tracking those: hdmi_enable_4kp60 and > enable_tvout .) > > https://www.raspberrypi.org/documentation/configuration/uart.md > > reports that the mini UART is tied to the core_freq, not > the arm_freq. > > So on a RPi4B where hdmi_enable_4kp60 and enable_tvout are > not changing, the core_freq assignment should also not be > changing, no matter what arm_freq changes are being made. > > That leaves core_freq_min for the RPi* firmware's dynamic > frequency clocking. The default is 250 or 275, apparently > depending on the status of hdmi_enable_4kp60, 275=550/2, > when hdmi_enable_4kp60 is enabled, otherwise 250 is used > (for the core_freq 500 and 360 cases). [The 360 > (enable_tvout) case is not well documented for > core_freq_min .] > > It is not clear when the dynamic frequency clocking > logic would adjust the actual core frequency but > it appears that the official way to avoid messing > up the mini UART is to assign: core_freq_min to > match the value of the core_freq setting so that > no other setting is available. > > If the mini UART is working in your context and you > have not disabled Bluetooth or redirected the UART > Bluetooth is using, what I infer is that the RPi* > firmware's dynamic frequency clocking happens to > not be adjusting the live core_freq significantly > in your context. > Powerd does seem to affect the apparent speed of the Pi, and seems to make it run a bit hotter, though I've not paid enough attention to know by how much. Trying another buildworld/kernel to get a sense of average speed. By any chance, was powerd enabled by default in the distant (year or so) past? Things seemed to slow down markedly after then. I always thought it was due to changes in clang. Thanks for writing! bob prohaska
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