Shutdown time for RPi-3?

It depends - mostly on how fast the SD card is, how many dirty buffers need to be flushed and how long processes take to die. Best bet is to measure it under your worst case loads with the card you intend to use and add a healthy safety factor.

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Also see if you can use Raspbian Lite and if that makes a significant difference (you probably don't use X anyway?).

Ok, reframing : What's the easiest way to detect when shutdown is complete?

Thanks! -F

A GPIO pin state? Is it 14 or 15 that's reliably hi/lo depending on run state?

If it's set by software, it's not reliable. Since this is part of a power down circuit, why not measure the power consumption. I'm pretty sure the numbers I've seen will make a clear distinction between running in a low power state and OFF. Power measurement is not so hard.

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Rick C

Hmmn, interesting idea. I have a hall-effect current probe that would probably do the job. Just have to hack the power connector.

Thanks ... seems like that should work! -F

Some boards use the serial Tx line. This is set low when shutdown is complete.

Other strategies are to minimise SD card writes during normal use, but we don't know what the application is.. However stuff I do is things like remove logging (like rsyslogd - no idea how to stop systemd writing to SD card, I don't use it), mounting /tmp/ as ramdisk (see /etc/defaults/shm ) and generally tuning application to minimise writes, if possible.

Gordon

I'll take a look at that too once I get my tech to make me the power cable with separable conductors needed for monitoring the current consumed. I'm also curious to see how much current the RPi consumes once it is shut-down (since it reboots after some 10s or so it must be running, at a minimum, some kind of timer/clock).

It's running a GUI that controls a research instrument. The only disk activity is very infrequent, to save altered instrument configuration/settings. At this point (the users may come up with changes in the future), there's no data logging.

Excellent idea to kill any syslog activities, etc., thanks!

-F

Not significantly different. Power isn't switched like in ATX PC power supplies, would draw more than potential savings.

I've tried a few experiments to reduce the shutdown/poweroff demand, to little effect. These all used "poweroff" or equivalent while the power supply actually remained on.

My test unit (connected to a 7" touch screen, powered separately) draws: ~ 350mA while idle (with or without X) ~ 500mA (avg) during the ~2sec it seems to take to shut down ~ 100mA after shutdown appears complete The 2s of "extended current draw" occurs after the screen blanks, which is nearly instantaneous - i.e. the screen blanking is misleadingly fast.

Preliminary attempts to quicken or reduce the magnitude of current during shutdown - by not using X, or stopping rsyslog have been completely ineffective.

The Tx line drops as suggested; at least it's coincident with the majority of the current dropping from ~500mA to ~100mA (there's 0.4 to 0.5s of

75mA more after the Tx line drop - hopefully that's not more "disk" activity).

Yuck. Probably gonna have to beef up my 5V supply's stored energy to avoid system flash data corruption. I may yet try a few things - there's lots of activity posted to syslog.

-F