Re: Laptop exhibits erratic responsiveness

On Sat, Nov 28, 2020 at 10:47:57AM -0500, Jonathan Looney wrote:
> FWIW, I would try running lockstat on the box. (My supposition is that the
> delay is due to a lock. That could be incorrect.  Lockstat may provide some
> clue as to whether this is a line of inquiry worth pursuing.)
> ....

Thanks (again), Jonathan.

So... I did that (during this morning's daily upgrade cycle); the
results may be "of interest" to some.

I have placed copies of the typescripts in:

http://www.catwhisker.org/~david/FreeBSD/head/lockstat/

I also scribbled a "README" in that same directory (though it doesn't
seem to show up in the listing); it may be accessed via

http://www.catwhisker.org/~david/FreeBSD/head/lockstat/README

My prior message in this thread showed what I saw during a "ping albert"
from the laptop while it was running head -- most RTTs were around 0.600
ms, but some were notably longer, with at least one that was over 68
seconds.

So I did a "lockstat ping -c 64 albert" while the laptop was running
stable/12_at_r368123 (as a reference point); it is probably boring. :-}

Then (this morning), I tried a simple "lockstat sleep 600" on the laptop
while it was running head_at_r368119 (and building head_at_r368143); we see
the "lockstat" output in the "lockstat_head" file.

It then occurred to me that trying a "lockstat ping albert" might be
useful, so I fired up "lockstat ping -c 600 albert" -- which started up
OK, and demonstrated some long RTTs about every 11 packets or so, but we
see thing come to a screeching halt with:

...
64 bytes from 172.16.8.13: icmp_seq=534 ttl=63 time=0.664 ms
lockstat: dtrace_status(): Abort due to systemic unresponsiveness
64 bytes from 172.16.8.13: icmp_seq=535 ttl=63 time=9404.383 ms

and we get no lockstat output. :-/


Finally, as another "control," I ran similar commands from freebeast,
while it was running head_at_r368119 (and building head_at_r368143).  Those
results are in the "lockstat_freebeast" file.

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.