Re: Oddities on Pi4 under -current

On Tue, Oct 12, 2021 at 09:33:49AM +1100, MJ wrote:
> 
> 
> On 12/10/2021 3:32 am, bob prohaska wrote:
> <snip>
> > The slow response to ssh login appeared only in the past week or so.
> > It isn't entirely reproducible, usually happening after  idle time.
> > The delay isn't more then five or ten seconds, but very noticeable.
> > 

[ping session omitted]

> The RPI4 has green-mode on idle. If your switch supports it, then it's activated. This might account for some delay, but that looks a little too large what you've reported. Maybe someone else with an RPI4 could provide a confirmation?
> 
> Reference: https://forums.raspberrypi.com/viewtopic.php?t=257144#p1569652
>
 
A power conservation feature seems a likely culprit, if one has been 
newly added or turned on.

The delayed response appeared after a world/kernel update, I think about
two weeks ago. I didn't make any manual config changes. Dropped ssh sessions
have been a problem for a while now, but this seems noticeably worse.  

Right now there are two ssh sessions open between my desktop machine
(Pi4 running WiFi on RaspiOS) and the Pi4 running -current. One is 
interactive, and has been up all day. The other is used to run a tip 
session to the serial console of a Pi2. That usually drops within half 
a day leaving a stale lock on the device file. At other times there
have been four or more ssh connections to the offending Pi4, only the
one running the serial connection seems to be affected. 

There are quite a few links in the chain: USB-serial adapter, wired
ethernet, router, WiFi and finally the RaspiOS workstation. The only
link associated with the trouble is the USB-serial adapter. 

Thanks for reading, and any hints where to look for the trouble.

bob prohaska