[Bug 257160] SCHED_4BSD produces nonsense in top.

From: <bugzilla-noreply_at_freebsd.org>
Date: Tue, 13 Jul 2021 18:53:14 UTC 
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=257160

            Bug ID: 257160
           Summary: SCHED_4BSD produces nonsense in top.
           Product: Base System
           Version: CURRENT
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: dgilbert@eicat.ca

While I'm testing this on riscv64, I strongly suspect that it's not
architecture dependant.  It may, however, depend on having a multi-cpu system.

Due to the nature of my quad-core risv64 (it's slow) and what I want to do with
it(it's fairly busy), I was annoyed that SCHED_ULE was mostly ignoring my nice
levels giving more than 0 time to processes marked as nice -20 vs. processes
not nice.  Anyways, I installed a kernel with SCHED_4BSD.

Keep in mind this is a quad core CPU:

  PID USERNAME    THR PRI NICE   SIZE    RES STATE    C   TIME    WCPU COMMAND
  604 dgilbert      1  45    0   109M    66M CPU3     3   0:02 1039.89% c++
  605 dgilbert      1  45    0   109M    66M CPU1     1   0:02 1031.29% c++
  606 dgilbert      1  45    0   109M    66M RUN      2   0:02 1020.32% c++
  603 dgilbert      1  44    0   109M    66M CPU0     0   0:02 1011.41% c++
  854 root          1  40    0    17M  4764K select   1   3:04   0.17% tmux
  425 root          1  40    0    14M  4040K CPU2     2   0:03   0.15% top

... that is a sample top output --- and the >100% _single thread_ processes
continue to be significantly more than 100% until they die.

Obviously, top is not reporting reality here.

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