What does scheduler/aux mean in msacc?

[Fernando Benavides]

Hi Erlangers,

It's me again… still trying to understand why my system behaves worse in
OTP22 than OTP21.
The last thing I tried was running MicroStateAccounting
<http://erlang.org/doc/man/msacc.html> on it and the results showed
something *odd*…

These are two of my summaries for OTP21:
Stats per type:
        Thread      *aux* check_io *emulator*       gc    other     port
 sleep
         async    0.00%    0.00%    0.00%    0.00%    0.00%    0.00%
 100.00%
           aux    0.23%    0.06%    0.00%    0.00%    0.09%    0.00%
99.62%
dirty_cpu_sche    0.00%    0.00%    0.01%    0.20%    0.00%    0.00%
99.79%
dirty_io_sched    0.00%    0.00%    0.00%    0.00%    0.00%    0.00%
 100.00%
          poll    0.00%    0.58%    0.00%    0.00%    0.00%    0.00%
99.42%
     scheduler    *2.05%*    0.56%   *71.29%*   13.25%    3.00%    1.89%
 7.96%
ok

Stats per type:
         async    0.00%    0.00%    0.00%    0.00%    0.00%    0.00%
 100.00%
           aux    0.23%    0.07%    0.00%    0.00%    0.08%    0.00%
99.62%
dirty_cpu_sche    0.00%    0.00%    0.01%    0.29%    0.00%    0.00%
99.70%
dirty_io_sched    0.00%    0.00%    0.00%    0.00%    0.00%    0.00%
 100.00%
          poll    0.00%    0.61%    0.00%    0.00%    0.00%    0.00%
99.39%
     *scheduler*    *2.26%*    0.56%   *68.70%*   12.69%    3.42%    1.89%
  10.48%
ok

These are the corresponding two summaries for OTP22 (same period of time,
same code, running the same things):
Stats per type:
        Thread      *aux* check_io *emulator*       gc    other     port
 sleep
         async    0.00%    0.00%    0.00%    0.00%    0.00%    0.00%
 100.00%
           aux    0.49%    0.06%    0.00%    0.00%    0.28%    0.00%
99.16%
dirty_cpu_sche    0.00%    0.00%    0.00%    0.19%    0.00%    0.00%
99.80%
dirty_io_sched    0.00%    0.00%    0.00%    0.00%    0.00%    0.00%
99.99%
          poll    0.00%    0.53%    0.00%    0.00%    0.00%    0.00%
99.47%
     *scheduler*    *6.26%*    0.52%   *63.83%*   14.41%    3.05%    1.72%
  10.20%
ok

Stats per type:
         async    0.00%    0.00%    0.00%    0.00%    0.00%    0.00%
 100.00%
           aux    0.39%    0.07%    0.00%    0.00%    0.18%    0.00%
99.36%
dirty_cpu_sche    0.00%    0.00%    0.00%    0.22%    0.00%    0.00%
99.78%
dirty_io_sched    0.00%    0.00%    0.00%    0.00%    0.00%    0.00%
99.99%
          poll    0.00%    0.51%    0.00%    0.00%    0.00%    0.00%
99.49%
     *scheduler*    *6.97%*    0.54%   *63.88%*   13.73%    3.19%    1.74%
   9.96%
ok

I highlighted the strange/different parts there, but in a nutshell:
The scheduler is spending more time *handling **auxiliary jobs *and less
time *executing Erlang processes *(for context
<http://erlang.org/doc/man/erlang.html#statistics_microstate_accounting>).
Can anybody give me a clue as to what to check next? How can I determine
what are those *auxiliary jobs* that the scheduler is working on now?

Thanks in advance :)


-- 
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Brujo Benavides
about.me/elbrujohalcon
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