Laptop exhibits erratic responsiveness

From: David Wolfskill <david_at_catwhisker.org>
Date: Sat, 28 Nov 2020 05:50:23 -0800
I've delayed trying to send this, as I wasn't clear on how to express it
-- and I had hoped that the problem would "go away" before I figured
that part out: I first observed it around 09 Nov, which is when I
updated the laptop (via in-place source upgrade, as usual) from r367484
to r367517.

One of the issues I faced with respect to expressing the nature of the
problem was "how to quantify" it.  And as I was trying to get some work
done on another machine, it ocurred to me that perhaps pinging that
other machine might illustrate things adequately, so:

g1-48(13.0-C)[17] ping albert
PING albert.catwhisker.org (172.16.8.13): 56 data bytes
64 bytes from 172.16.8.13: icmp_seq=0 ttl=63 time=0.511 ms
64 bytes from 172.16.8.13: icmp_seq=1 ttl=63 time=0.667 ms
64 bytes from 172.16.8.13: icmp_seq=2 ttl=63 time=0.537 ms
64 bytes from 172.16.8.13: icmp_seq=3 ttl=63 time=0.618 ms
64 bytes from 172.16.8.13: icmp_seq=4 ttl=63 time=0.647 ms
64 bytes from 172.16.8.13: icmp_seq=5 ttl=63 time=0.538 ms
64 bytes from 172.16.8.13: icmp_seq=6 ttl=63 time=0.538 ms
64 bytes from 172.16.8.13: icmp_seq=7 ttl=63 time=0.543 ms
64 bytes from 172.16.8.13: icmp_seq=8 ttl=63 time=0.571 ms
64 bytes from 172.16.8.13: icmp_seq=9 ttl=63 time=0.500 ms
64 bytes from 172.16.8.13: icmp_seq=10 ttl=63 time=0.618 ms
64 bytes from 172.16.8.13: icmp_seq=11 ttl=63 time=0.548 ms
64 bytes from 172.16.8.13: icmp_seq=12 ttl=63 time=0.532 ms
64 bytes from 172.16.8.13: icmp_seq=13 ttl=63 time=0.532 ms
64 bytes from 172.16.8.13: icmp_seq=14 ttl=63 time=0.613 ms
64 bytes from 172.16.8.13: icmp_seq=15 ttl=63 time=0.593 ms
64 bytes from 172.16.8.13: icmp_seq=16 ttl=63 time=0.501 ms
64 bytes from 172.16.8.13: icmp_seq=17 ttl=63 time=0.630 ms
64 bytes from 172.16.8.13: icmp_seq=18 ttl=63 time=0.556 ms
64 bytes from 172.16.8.13: icmp_seq=19 ttl=63 time=0.566 ms
64 bytes from 172.16.8.13: icmp_seq=20 ttl=63 time=0.642 ms
64 bytes from 172.16.8.13: icmp_seq=21 ttl=63 time=0.611 ms
64 bytes from 172.16.8.13: icmp_seq=22 ttl=63 time=0.628 ms
64 bytes from 172.16.8.13: icmp_seq=23 ttl=63 time=92.473 ms
64 bytes from 172.16.8.13: icmp_seq=24 ttl=63 time=0.647 ms
64 bytes from 172.16.8.13: icmp_seq=25 ttl=63 time=0.483 ms
64 bytes from 172.16.8.13: icmp_seq=26 ttl=63 time=0.476 ms
64 bytes from 172.16.8.13: icmp_seq=27 ttl=63 time=0.561 ms
64 bytes from 172.16.8.13: icmp_seq=28 ttl=63 time=0.560 ms
64 bytes from 172.16.8.13: icmp_seq=29 ttl=63 time=0.599 ms
64 bytes from 172.16.8.13: icmp_seq=30 ttl=63 time=0.677 ms
64 bytes from 172.16.8.13: icmp_seq=31 ttl=63 time=0.563 ms
64 bytes from 172.16.8.13: icmp_seq=32 ttl=63 time=0.609 ms
64 bytes from 172.16.8.13: icmp_seq=33 ttl=63 time=0.558 ms
64 bytes from 172.16.8.13: icmp_seq=34 ttl=63 time=0.527 ms
64 bytes from 172.16.8.13: icmp_seq=35 ttl=63 time=0.610 ms
64 bytes from 172.16.8.13: icmp_seq=36 ttl=63 time=0.621 ms
64 bytes from 172.16.8.13: icmp_seq=37 ttl=63 time=0.501 ms
64 bytes from 172.16.8.13: icmp_seq=38 ttl=63 time=68482.244 ms
64 bytes from 172.16.8.13: icmp_seq=39 ttl=63 time=0.672 ms
64 bytes from 172.16.8.13: icmp_seq=40 ttl=63 time=0.635 ms
64 bytes from 172.16.8.13: icmp_seq=41 ttl=63 time=0.585 ms
64 bytes from 172.16.8.13: icmp_seq=42 ttl=63 time=0.629 ms
64 bytes from 172.16.8.13: icmp_seq=43 ttl=63 time=0.566 ms
64 bytes from 172.16.8.13: icmp_seq=44 ttl=63 time=0.641 ms
64 bytes from 172.16.8.13: icmp_seq=45 ttl=63 time=0.638 ms
64 bytes from 172.16.8.13: icmp_seq=46 ttl=63 time=0.645 ms
64 bytes from 172.16.8.13: icmp_seq=47 ttl=63 time=0.540 ms
64 bytes from 172.16.8.13: icmp_seq=48 ttl=63 time=0.487 ms
64 bytes from 172.16.8.13: icmp_seq=49 ttl=63 time=13.063 ms
64 bytes from 172.16.8.13: icmp_seq=50 ttl=63 time=0.567 ms
64 bytes from 172.16.8.13: icmp_seq=51 ttl=63 time=0.487 ms
64 bytes from 172.16.8.13: icmp_seq=52 ttl=63 time=0.428 ms
64 bytes from 172.16.8.13: icmp_seq=53 ttl=63 time=0.692 ms
64 bytes from 172.16.8.13: icmp_seq=54 ttl=63 time=0.605 ms
64 bytes from 172.16.8.13: icmp_seq=55 ttl=63 time=0.630 ms
64 bytes from 172.16.8.13: icmp_seq=56 ttl=63 time=0.561 ms
64 bytes from 172.16.8.13: icmp_seq=57 ttl=63 time=0.634 ms
64 bytes from 172.16.8.13: icmp_seq=58 ttl=63 time=0.571 ms
64 bytes from 172.16.8.13: icmp_seq=59 ttl=63 time=0.577 ms
64 bytes from 172.16.8.13: icmp_seq=60 ttl=63 time=0.592 ms
64 bytes from 172.16.8.13: icmp_seq=61 ttl=63 time=0.455 ms
64 bytes from 172.16.8.13: icmp_seq=62 ttl=63 time=0.585 ms
64 bytes from 172.16.8.13: icmp_seq=63 ttl=63 time=0.548 ms
64 bytes from 172.16.8.13: icmp_seq=64 ttl=63 time=0.443 ms
64 bytes from 172.16.8.13: icmp_seq=65 ttl=63 time=0.584 ms
64 bytes from 172.16.8.13: icmp_seq=66 ttl=63 time=0.592 ms
^C
--- albert.catwhisker.org ping statistics ---
67 packets transmitted, 67 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.428/1024.248/68482.244/8303.513 ms
g1-48(13.0-C)[18] 

Please note that no packets are dropped, and that most exhibit an RTT of
around 0.6 ms, and that no packets are dropped -- which is ... good, as
far as that goes.  (The laptop is presently using a wired Ethernet
(em0) link, as "wireless" doesn't play well with significant lags in
response time, or so it appears to me.)

But packet 23 shows a hint of something gone awry, and packet 38 ...
something's gone walkabout, and is in no hurry to return.

While the above "ping" was done during the upgrade from r368097 to
r368119, I have observed similar effects when the machine was idle (but
running head).  I do NOT observe these effects when the machine is
running stable/12 (also tracked/updated daily), nor have I seen the
behavior on other machines (my build machine, which also tracks head and
stable/12 daily; various machines at work, which generally track head
about every 4 - 5 weeks).

Any ideas for tracking this down?

I have documented various aspects of what process I use to track/uodate
the machines, the environment, and the history of the tracking:

* http://www.catwhisker.org/~david/FreeBSD/upgrade.html
* http://www.catwhisker.org/~david/FreeBSD/history/

Thanks!

Peace,
david
-- 
David H. Wolfskill                              david_at_catwhisker.org
"Make America Great Again," he said -- and THIS is what he did??!?

See http://www.catwhisker.org/~david/publickey.gpg for my public key.

Received on Sat Nov 28 2020 - 12:50:33 UTC

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