Strange behavior after running under high load

[Stefan Esser]

Am 28.03.21 um 17:44 schrieb Andriy Gapon:
> On 28/03/2021 17:39, Stefan Esser wrote:
>> After a period of high load, my now idle system needs 4 to 10 seconds to
>> run any trivial command - even after 20 minutes of no load ...
>>
>>
>> I have run some Monte-Carlo simulations for a few hours, with initially 35
>> processes running in parallel for some 10 seconds each.
> 
> I saw somewhat similar symptoms with 13-CURRENT some time ago.
> To me it looked like even small kernel memory allocations took a very long time.
> But it was hard to properly diagnose that as my favorite tool, dtrace, was also
> affected by the same problem.

That could have been the case - but I had to reboot to recover the system.

I had let it sit idle fpr a few hours and the last "time uptime" before
the reboot took 15 second real time to complete.

Response from within the shell (e.g. "echo *") was instantaneous, though.

I tried to trace the program execution of "uptime" with truss and found,
that the loading of shared libraries proceeded at about one or two per
second until all were attached and then the program quickly printed the
expected results.

I could probably recreate the issue by running the same set of programs
that triggered it a few hours ago, but this is a production system and
I need it to be operational through the week ...

Regards, STefan

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